担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MYU K.K.  

DOI： 10.18494/sam.2021.3446

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

First-principles energy band calculations are performed for Y2BaCuO5 (YBC211) with ferromagnetic and three types of antiferromagnetic (AFM) spin orderings, namely, A, C, and G. The most stable phase is found to be G AFM ordering (AFM_G_YBC211). The calculated magnetic moment at the Cu sites is almost identical to the experimental one reported in the literature. However, the energy bandgap is estimated to be only 035 eV. The valence band (VB) maximum locates on the S-Gamma line and the conduction band (CB) minimum locates at the Gamma point, suggesting that AFM_G_YBC211 is an indirect bandgap oxide. From the density-of-states analysis, the VB of AFM_G_YBC211 comprises mainly the Cu 3d and 0 2p states. The lower CB comprises the Cu 3d states, whereas the upper CB is attributed mainly to the Y 4d, Ba 5d, and O 2p states. Furthermore, in the dielectric function calculation of AFM_G_YBC211, the epsilon(2)(omega) curves exhibit very strong peaks for the yy and zz components at 0.87 eV, whereas the corresponding peak for the xx component is weak. This difference is attributed to the anisotropy of the momentum matrix elements between the VB and the lower CB. (C) 2020 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.20154

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

A first-principles energy band calculation is performed with respect to the V5+- and (Ca2+, V5+)-doped Y2Ti2O7 supercells to elucidate the effect of Ca2+ doping on the electronic structure and optical properties of a V5+-doped Y2Ti2O7 pigment in the present study. The structural optimization calculation reveals that the theoretical lattice constant of the Y2Ti2O7 unit cell slightly increases when compared with that in the experimental data. The forbidden gap at the r point is estimated to be 2.78 eV. On the basis of the density-of-states analysis, the valence band (VB) of Y2Ti2O7 mainly comprises the O 2p states and hybridizes with the Ti 3d and 4d states. The conduction band (CB) can be divided into two energy regions. The lower CB comprises the Ti 3d states and hybridizes with the O 2p states, whereas the upper CB comprises the Y 4d, Ti 3d, and O 2p states. When Y2Ti2O7 is doped with a V atom, the VB width and bandgap are observed to expand by 0.7 and 0.2 eV, respectively, with respect to the pristine Y2Ti2O7. Two strongly localized peaks, corresponding to the V 3d states, appear in the bandgap. Further, three strongly localized peaks appear in the bandgap when V5+-doped Y2Ti2O7 is doped with a Ca atom. In the dielectric function calculation of the V5+-doped Y2Ti2O7, there is broad absorption from the O 2p VB states to the V 3d gap states as well as a VB-CB optical transition in the host crystal. When the V5+-doped V2Ti2O7 is doped with a Ca atom, the distortion of the VO6 octahedron becomes large, leading to an increment of 0 2p state densities near the valence-band maximum of the host. Thus, it is considered the momentum matrix elements between occupied states (O 2p states) and unoccupied states (V 3d states) becomes large in comparison with the case before a Ca doping. (C) 2019 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.19103

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

proton conductive characteristics of La1-xBaxYbO3-delta (x=0.02, 0.06, 0.10) were examined by an impedance analysis in the temperature range of 873-1473 K. The maximum proton concentrations in La1-xBaxYbO3-delta determined by the weight changes were almost 1/5 of the oxygen vacancies formed by the substitution of Ba. This result indicated that at least two types of oxygen vacancies, a hydratable oxygen vacancy and hydration independent one, exist in the crystal. The bond distances and electronic structure of the Ba-substituted LaYbO3 supercell with or without an oxygen vacancy were investigated by the first-principles molecular dynamics calculations. The substitution of Ba for the La-site of LaYbO3 was found to induce the local structure change of oxygen atoms surrounding the La atom. (C) 2018 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2018.08.062

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Electronic structures and optical properties of CuMgVO4 and AgMgVO4 with optimized structures were investigated using the generalized gradient approximation proposed by Perdew-Burke-Ernzerhof and the Heyd-Scuseria-Ernzerhof hybrid functional. From the energy band calculation, we found that CuMgVO4 and AgMgVO4 have indirect band gaps. The upper valence band is mainly composed of fully occupied Cu 3d (Ag 4d) states, and the lower is mainly comprises O 2p states. The conduction band can be divided into two regions because of the crystal-field splitting by the interaction between the V 3d and the O 2p states. The optical properties of CuMgVO4 and AgMgVO4 were predicted from the complex dielectric function, epsilon(omega) = epsilon(1)(omega) + i epsilon(2)(omega). The static dielectric constants were estimated from the real part of the dielectric functions, epsilon(1)(omega). The imaginary part of the dielectric functions, epsilon(2)(omega), demonstrated optical anisotropy, with the component along the z (y) direction being larger than the others for CuMgVO4 (AgMgVO4) in the wavelength range of visible light. The absorption coefficient I(omega) was also calculated from the dielectric function. (C) 2019 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.18167

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

In this study, we investigate the changes in electronic and structural properties of a graphene layer deposited on a (root 3 x root 3) R30 degrees SiC (0001) surface before and after hydrogen intercalation using first-principles energy band calculations. Before hydrogen adsorption, the bond distance between the first graphene layer (FGL) and an Si atom on SiC surface is calculated to be 0.2285 nm, which is close to the value reported in the literature. After hydrogen adsorption, the layer distance between SiC surface and FGL tends to increase. The adsorption energy of hydrogen on SiC surface as estimated from the total energy change before and after hydrogen adsorption is relatively small. Thus, we suggest that hydrogen easily bonds to Si dangling bonds on SiC surface. When Si dangling bonds on SiC surface are passivated by hydrogen, the graphene layer on SiC functions as a quasi-free-standing graphene layer, whether the graphene exfoliates or not. Therefore, our results indicate the effectiveness of the hydrogen intercalation technique to create quasi-free-standing epitaxial graphene on Si-face SiC (0001) substrate. (C) 2019 The Japan Society of Applied Physics

DOI： 10.7567/1347-4065/aafb4a

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The electronic structure of LaYbO3 was investigated by the full potential linearized augmented plane wave plus local orbital (FLAPW + lo) method with the modified Becke-Johnson potential combined with the local density approximation correlation plus onsite Coulomb interaction (MBJ-LDA + U) for the sake of localized f electrons. This approach was suitable for evaluating electronic structure of LaYbO3 system from view point of calculation cost and time. The band gap, the difference in energy between the valence band (VB) and conduction band (CB), was estimated to be 6.0 eV by the present method. The evaluated value was very close to the reported experimental value. In the VB, Yb 4f orbitals and O 2p orbitals were well hybridized each other to state predominantly. The lower potential region in CB was mainly composed of La 4f orbitals, while the upper region in CB was mainly consisted of La 5d orbitals. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.commatsci.2016.09.005

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

ZnO1-xSx films were deposited on quartz substrates by pulsed laser deposition (PLD) of ZnO1-xSx targets. The ZnO1-xSx films with S-contents of 0.03-0.17 were grown from the ZnO1-xSx targets sulfured at temperatures of 200 and 500 degrees C. The resistivity of the ZnO1-xSx films is slightly increased with the S-content. An increase of the O-2-partial pressure in an atmosphere reduces the S-content in the films and drastically enhances the resistivity of the films. However, the carrier type of the films is still n-type. In order to incorporate excess S atoms into films, evaporation of Sulfur was performed during the PLD process. As a temperature of the S-evaporation is raised, the resistivity of the films is significantly enhanced and hole-conductivity appears in the films grown by the S-evaporation at 80 and 90 degrees C. By Xray photoelectron spectroscopic measurements, the presence of SOx species is confirmed for the p-type ZnO1-xSx film. Both interstitial SO3 or SO4 clusters and complexes of Zn-vacancy with H are considered to be appropriate acceptors responsible for the hole-conductivity at room temperature. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jcrysgro.2016.06.029

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

The first-principles energy band calculation for M3Ta6Si4O26 (M = Ba, Sr) with optimized structure is performed using the Tran-Blaha (TB) exchange potential combined with correlation potential from the local density approximation (LDA). The theoretical minimum band gaps of Ba3Ta6Si4O26 and Sr3Ta6Si4O26 are estimated to be 4.39 and 4.46 eV, respectively. These results are in large contrast to the underestimation based on the generalized gradient approximation calculation. The band gaps of M3Ta6Si4O26 (M = Ba, Sr) hardly changed with the spin-orbit interaction. The main conduction band can be divided into two energy regions near 7.6 eV due to the octahedral crystal-field splitting based on the interaction between Ta-d and O-p states. On the other hand, the main valence band in the energy range of -5.3 to 0 eV is constructed from O-p states, where the Ta-d states hybridize strongly with the O-p states. The optical properties of M3Ta6Si4O26 (M = Ba, Sr) are predicted from the complex dielectric function epsilon(omega) = epsilon(1)(omega) + i epsilon(2)(omega). Polarized peaks in the z-direction appear at 5.5 and 6.4 eV for Ba3Ta6Si4O26, 5.6 and 6.6 eV for Sr3Ta6Si4O26 in the epsilon(2)(omega) function, respectively. The absorption coefficient estimated from the TB-LDA is very similar to the experimental result obtained in the literature. (C)2017 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.17046

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

The effect of Si addition was studied for the purpose of the improvement of microstructure of MgFe2O4 particles prepared from a malic acid complex. There were no traces of any impurity phase in Si-doped and pure MgFe2O4 powders both in XRD measurements. When Si atoms were doped to MgFe2O4, crystallite growth of MgFe2O4 was remarkably suppressed, and the lattice volume increased up to 10 mol% Si monotonously. SEM observations revealed that MgFe2O4 powders show a granulation shape such as the aragonite and each particle tightly interconnected each other, whereas smaller particles compared with pure MgFe2O4 were observed for Si-doped MgFe2O4. Also, it was found that the amount of mesopore increases by Si doping. Further, XPS and XAS measurements suggested that Si atoms exist in MgFe2O4 crystal. (C) 2016 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.16042

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

The electronic structures of Ag6M2O7 (M = Si, Ge) are investigated by the scalar-relativistic full potential linearized augmented plane wave plus local orbital (FLAPW+lo) method using the modified Becke-Johnson (MBJ) potential combined with the local density approximation (LDA) correlation. For Ag6M2O7 (M = Si, Ge), the valence band maximums (VBM) are approximately located at the X (Si) or A (Ge) and the conduction band minimums (CBM) at the Gamma both, indicating that Ag6M2O7 are an indirect energy gap material. The fundamental band gaps of Ag6Si2O7 and Ag6Ge2O7 are calculated to be 1.69 and 1.42 eV, respectively, in the MBJ-LDA calculation. The results are a remarkably contrast to the underestimation based on the generalized gradient approximation (GGA) calculation. On the other hand, there is no distinct difference in the effective masses of photogenerated holes and electrons near the VBM and CBM between MBJ-LDA and GGA approaches. The optical properties of Ag6M2O7 (M = Si, Ge) are contemplated from spectral dependence of the complex dielectric function, epsilon (omega) = epsilon(1) (omega) + i epsilon(2) (omega). (C) 2016 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.15208

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Single-phase Sr2Bi2O5 was obtained by calcination of the heterobimetallic complex precursor Sr [Bi(DTPA)]center dot 9H(2)O (DTPA is diethylenetriaminepentaacetic acid) at 700 degrees C for 6 h. The effect of La doping on the crystal structure, surface area, morphology, surface chemical state, and absorption properties of Sr2Bi2O5 samples prepared from Sr[Bi(DTPA)]center dot 9H(2)O were investigated. No traces of an impurity phase were detected in samples with a lower La content (3 and 5 mol%), while impurity phases such as Sr2Bi2O5 and SrCO3 were observed in Sr2Bi2O5 samples with larger La contents of 8 and 10 mol%. The Brunauer-Emmett-Teller surface area of Sr2Bi2O5 increased slightly with the content of La. High-resolution transmission electron microscopy revealed clear crystalline planes for both undoped and La-doped Sr2Bi2O5 samples without amorphous phases. Meanwhile, X-ray photoelectron spectroscopy indicated that the valence states of constituent metals were Sr2+, Bi3+, and La3+. The solubility limit of La in the Sr2Bi2O5 crystal phase was determined from Raman scattering measurements. La atoms substituted Bi sites when the doping content was low, while both Bi and Sr sites were substituted with La when the content of La was high. The electronic structure of Sr2Bi2O5 could be modified by La doping, resulting in a red shift of the absorption edge with increasing La content. The band-gap narrowing of Sr2Bi2O5 with La-doping was reproduced in energy-band calculations. The photocatalytic activity of Sr2Bi2O5 under visible-light irradiation for the oxidation of isopropanol was enhanced by doping with La. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2015.10.199

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MYU, SCIENTIFIC PUBLISHING DIVISION  

The gas sensing properties of Zr-added and pure CaFe2O4 powders for CO2 in air were examined in the temperature range of 250-450 degrees C. The semiconductor-type gas sensor made from pure CaFe2O4 powder showed a fairly good response to CO2. Furthermore, the addition of a small amount of Zr into CaFe2O4 powder was found to be effective for enhancing the CO2 response of the present gas sensor. It was also found that the gas response, defined by the ratio of the resistance in air and that of the target gas reached maximum at the operating temperature of 300 degrees C. The gas response of the Zr-added CaFe2O4-based sensor at 300 degrees C was estimated to be 2.5 times higher than that of the sensor made from pure CaFe2O4 powder. However, the 90% response time of the Zr-added CaFe2O4-based sensor was much quicker at 350 degrees C than that at 300 degrees C. Thus, the optimal gas sensing performance of the Zr-added CaFe2O4-based sensor is expected to be obtained at the operating temperature of 350 degrees C, considering the still higher response to CO2 gas at this temperature. It is noted that the present CaFe2O4-based sensor responded reversibly as well as continuously to CO2 gas. Infrared analysis revealed that the sensing mechanism of the present CaFe2O4-based sensor is the change in the electric resistance of CaFe2O4 caused by reactive CO2 adsorption with negatively charged oxide ions (O-) resulting in the increase in the hole concentration in the base material of CaFe2O4.

DOI： 10.18494/SAM.2016.1277

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jssc.2015.09.032

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.tetlet.2015.01.159

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The electronic structures of uncloped and Eu2+-doped SrAl2O4 clusters are evaluated from the relativistic molecular orbital (RMO) calculation. The calculated forbidden gaps between the highest and lowest unoccupied molecular orbitals of [SrAl2O21](22-) and [SrAl12O38](34-) clusters are calculated to be 83 and 7.3 eV, respectively. When a Eu atom replaces a Sr atom, the Eu 4f states appear in the forbidden gap of the SrAl2O4 and the Eu 5d states are distributed widely in the conduction band. Combining the RMO calculation and the configuration interaction method for [EuO7](12-) and [EuO8](14-) clusters produces three or two theoretical peaks respectively for the transition 4f(7) -> 4f(6) 5d(1) in Eu2+-doped SrAl2O4, respectively. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ssc.2015.01.013

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

The effect of Zr addition into malic acid complex was examined for the purpose of the improvement of microstructure and specific surface area of CaFe₂O₄. The CaFe₂O₄ phase could be obtained for both unadded and Zr-added (5 and 10 mol % with respect to Fe) system by calcination of precursor derived from malic acid complex at 700°C which is almost 200°C lower than that of conventional solid-state reaction method. Among the examined products, only the 5 mol % Zr-added product revealed characteristic smaller grains connected three dimensional porous structures resulting in higher specific surface area compared with unadded and 10 mol % Zr-added products. XPS measurements revealed that there are no notable changes in valence state for all constituent elements. The obtained final product of 5 mol % Zr-added CaFe₂O₄ is worth further investigate for various application from a view point of improved higher specific surface area and characteristic microstructure as well as the functionality of the material itself.

DOI： 10.2109/jcersj2.123.995

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本化学会  

Single-phase Sr₂Bi₂O₅ was formed by calcination of the heterobimetallic complex, Sr[Bi(DTPA)]·9H₂O, at 700 °C for 6 h in air. La-doping by 5 and 10 mol % into Sr₂Bi₂O₅ was also examined. There were no traces of impurity phase in the 5 mol % La-doped Sr₂Bi₂O₅ powder, on the other hand, impurity phases such as Sr₃Bi₄O₉ and SrCO₃ were identified for the 10 mol % La-doped sample. UV–vis spectroscopy revealed that the absorption edge of La-doped Sr₂Bi₂O₅ exhibits red shift as compared to the pure Sr₂Bi₂O₅ and the shift increases with the increase of La³⁺ doping. It was confirmed that the photocatalytic activity of Sr₂Bi₂O₅ for the oxidation of isopropanol is improved with La doping under visible-light irradiation (λ ≥ 420 nm).

DOI： 10.1246/cl.150178

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Nanopowder of MgFe2O4 was prepared from an organic acid complex method. Among three kinds of organic acids examined, it was found from an XRD measurement that the highest purity powder of MgFe2O4 was obtained from a malic acid complex. SEM observation revealed that the powder is fluffy aggregates and each particle has irregular shape. The TG-DTA and IR measurements show that thermolysis process of a malic acid complex in air was mainly constructed at two stages consisting of dehydration and ligand pyrolysis. Furthermore, it was confirmed from a VSM measurement that the saturation magnetization of MgFe2O4 nanopowder is much smaller value than that of the bulk material. (C) 2014 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.122.645

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

ZnO films have been prepared at substrate temperatures of 125 to 200 degrees C by chemical vapor deposition with a precursor of Zn4O(CH3COO) 6. As the substrate temperature decreases, the grain size of ZnO crystals decreases. From transmission electron microscopic observations, the film grown at 125 degrees C is found to be constructed from ZnO quantum dots with a diameter of ca. 5 nm. Ultraviolet emissions are seen at 367, 375, 380, and 384nm in photoluminescence spectra of the ZnO films grown at 125, 150, 175, and 200 degrees C, respectively. The blue shift of the ultraviolet emissions is ascribed to the quantum confinement effect. After the deposition of a Ga2ZnO4 film with a thickness of 20 nm on the ZnO QD film grown at 125 degrees C, a visible emission disappears and the ultraviolet emission intensity significantly increases. Such an increase is due to the partial embedding of ZnO QDs in Ga2ZnO4 films. The insertion of the ZnO QD films in the p-i-n devices constructed from In1.8Zn0.2O3/InGaZnO4/ Ga2ZnO4/Ni0.7Zn0.3O/Ni does not improve their rectification properties, and electroluminescence is not observed in these devices at forward voltages of 10V or more. (C) 2014 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.53.06JG09

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The optimized electronic structure of Eu2+-doped SrAl2O4 is calculated by using the modified Becke-Johnson potential combined with the local density approximation. The calculated minimum energy gap of SrAl2O4 is 6.9 eV, which is close to the experimental value (similar to 6.5 eV). When a Eu atom replaces one of the Sr atoms, Eu 4f majority-spin states appear in the forbidden gap of SrAl2O4, which is estimated to be 5.5 eV above the valence band maximum. Considering spin-orbit coupling, Eu 4f majority-spin states decompose into two energy states and Eu 4f minority-spin states also appear in the band gap of SrAl2O4. (C) 2014 Elsevier Ltd. All rights reserved,

DOI： 10.1016/j.ssc.2014.01.026

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The electronic structure of Sr2Bi2O5 is calculated by the scalar-relativistic full potential linearized augmented plane wave (FLAPW+lo) method using the modified Becke-Johnson potential combined with the local density approximation correlation (MBJ-LDA). Both the valence band maximum (VBM) and conduction band minimum (CBM) exist at the F-point, indicating that Sr2Bi2O5 is a direct-band-gap material. The band gap is calculated to be 3.17 eV, which is very close to the experimental value. This result is in great contrast to the underestimation based on the GGA calculation. On the other hand, there is only a small difference in the effective masses of holes and electrons photogenerated near the VBM and CBM for the MBJ-LDA and GGA approaches. The optical properties of Sr2Bi2O5 are calculated from the complex dielectric function epsilon(omega)=epsilon(1)(omega)+i epsilon(2)(omega). A highly polarized peak is observed at 3.5 eV in the epsilon(2)(omega) function. Furthermore, the absorption coefficient estimated from the MBJ-LDA is very similar to that from the experimental result. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2013.11.015

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Ti-doped and undoped CaFe2O4 powders were prepared from a malic acid complex and their properties were evaluated using analytical instruments. According to an XRD measurement, there were no traces of impurity phases in 5 mol % Ti-doped CaFe2O4 powder, while impurity phases such as alpha-Fe2O3 and CaTiO3 were observed for 10 mol % Ti-doped CaFe2O4. When Ti was added to CaFe2O4, the crystallite growth of CaFe2O4 was suppressed and the BET surface area increased. SEM observation revealed that the addition of Ti atoms to CaFe2O4 causes interconnected CaFe2O4 particles to separate. From the results of an XRF measurement, it is suggested that Fe atoms are substituted with Ti atoms. The optical band gap of CaFe2O4 hardly changed as a result of doping with Ti. (C) 2014 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.122.175

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

The electronic structure of antiferromagnetic CaFe2O4 is calculated by using a generalized gradient approximation considering on-site Coulomb interaction between d-electrons (GGA+U). We found that the antiferromagnetic phase is the most stable among non-magnetic, ferromagnetic, and antiferromagnetic phases. With GGA+U, the band gap energy of CaFe2O4 is calculated to be ca. 1.9 eV. The lower conduction band consists of the Fe 3d states split into t(2g) and e(g) states by the octahedral FeO6 environment. The Ca 3d states distribute upper conduction bands. On the other hand, the valence band is mainly composed of the interaction between Fe 3d and O 2p states. The valence band maximum is approximately located at the Z-point and the conduction band minimum at the X-point. This means that antiferromagnetic CaFe2O4 is an indirect energy gap material. The absolute value of the magnetic moment at Fe sites is calculated to be 4.16 mu(B), which is very close to experimental values. (C)2013 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.121.766

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

The electronic structure of Ca 4Bi 6O 13 is calculated by the GGA approach. The valence band maximum and the conduction band minimum of Ca 4Bi 6O 13 are located at Γ-point. This means that Ca 4Bi 6O 13 is a direct band gap material. The conduction band in the lower energy region is mainly constructed with the admixture of Bi 6p and O 2p. The conduction band in the higher energy region consists of Ca 3d states. The valence band in the lower energy region is mainly formed from Bi 6s states, and the valence band in the upper energy region consists of O 2p states hybridizing with Bi 6s and 6p states. The optical properties of Ca 4Bi 6O 13 are calculated from spectral dependence of the complex dielectric function, ε(ω)=ε 1(ω)iε 2(ω). A highly polarized peak is observed below 3.6 eV in ε 2(ω) function. © 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2012.07.012

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

A p-type ZnO film was successfully obtained by the alternate deposition of ZnO and Mg 3N 2 in radio-frequency (RF) magnetron sputtering process. ZnO and Mg 3N 2 (or Mg-oxynitride) films were alternately deposited on a substrate rotated above ZnO and Mg 3N 2 targets, where ZnO and Mg 3N 2-sputtering were carried out at RF power of 30 W and 0-90 W, respectively. In the case of the alternate deposition, where the substrate was kept for 0.2 s above the Mg 3N 2 target, p-type ZnO films were grown by Mg 3N 2-sputtering at 50-70 W, whereas an n-type ZnO film was grown at 90 W. The c-axis lengths of the films prepared by Mg 3N 2-sputtering at 0-50 W increase with RF power, and oppositely the c-axis lengths of the films prepared by Mg 3N 2-sputtering at 60-90 W decrease with RF power. p-type ZnO films were grown by Mg 3N 2-sputtering at 50 W for 2 and 5 s, whereas insulative ZnO films were grown by Mg 3N 2-sputtering at 70 W for 2 and 5 s. The band-gap energies of the p-type ZnO films prepared by Mg 3N 2-sputtering at 50 W for 0.2 and 5 s are estimated to be 3.31 and 3.39 eV, respectively. The increase of the band-gap energies of the p-type ZnO films is caused by the intermixing of ZnO and Mg-oxynitride films. © 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2012.08.003

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1166/nnl.2012.1370

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

Films were deposited on a glass substrates heated at 100 degrees C by alternate deposition of ZnO and Mg3N2 films in an atmosphere of N-2 + 0.2% O-2. p-type ZnO films with the resistivity of 9.9x10(3) - 4.5x10(3) Omega cm were grown by Mg3N2 sputtering for 0.2 s at 50-70 W, whereas an n-type ZnO film was grown for 0.2 s at 90 W. Appearance of the n-type ZnO film is caused by a decrease of O-2-partial pressure in an atmosphere. The contraction of the c-axis due to the incorporation of Mg atoms is found in these p-type and n-type ZnO films. When the Mg3N2-depostion period was extended to 5s, p-type ZnO films were grown in the alternate sputtering at 50 W, whereas only insulator films were grown in the alternate sputtering at 70 W. The optical band gap of the films increases with both a RF power and a period of Mg3N2-deposition. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of MRS-Taiwan

DOI： 10.1016/j.proeng.2012.03.062

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1166/nnl.2012.1378

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The electronic structure of Sr(2)Bi(2)O5 is calculated by the GGA approach. Both of the valence band maximum and the conduction band minimum are located at Gamma-point. This means that Sr2Bi2O5 is a direct band-gap material. The wide energy-band dispersions near the valence band maximum and the conduction band minimum predict that holes and electrons generated by band gap excitation have a high mobility. The conduction band is composed of Bi 6p, Sr 4d and O 2p energy states. On the other hand, the valence band can be divided into two energy regions ranging from -9.5 to -7.9 eV (lower valence band) and from -4.13 to 0 eV (upper valence band). The former mainly consists of Bi 6s states hybridizing with O 2s and O 2p states, and the latter is mainly constructed from O 2p states strongly interacting with Bi 6s and Bi 6p states. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2011.08.030

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

A single phase of Ca4Bi6O13 crystal was obtained at lower calcination temperature in a citric acid complex method than in a solid-state reaction. From the diffuse reflection spectra, it was found that Ca4Bi6O13 is direct-gap material and that the optical band gap is 2.92 eV. After heating at 600 degrees C or above, the specific surface area of Ca4Bi6O13 powder was ca. three times larger when prepared by a citric acid complex method than by solid-state reaction. Further, it was confirmed that the photocatalytic activity of Ca4Bi6O13 for the degradation of Methylene Blue (MB) was higher in a citric acid complex method than in a solid-state reaction under visible-light irradiation (lambda >= 420 nm).

DOI： 10.1246/cl.2011.288

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WILEY-V C H VERLAG GMBH  

Amorphous InGaZnO4 (IGZO) films codoped with Al and N atoms were prepared by sputtering of targets consisting of IGZO and AlN powders in Ar + O-2 atmospheres. No hole-conductivity is seen in films deposited at 2x10(-3) Torr, whereas hole-conductivity is found in films deposited at 2x10(-2) Torr at radio frequency powers of 60-80 W in 0.3-0.6% O-2 atmospheres. The amorphous p-type IGZO film has the resistivity of 210 Omega cm, hole-density of 7.5x10(17) cm(-3), and mobility of 0.4 cm(2)/Vs. The rectification characteristic is obtained for a device constructed from Au, amorphous p-type IGZO, and amorphous n-type IGZO. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

DOI： 10.1002/pssc.201000442

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

The electronic structure of CaBi2O4 is calculated by a GGA approach. The valence band maximum is approximately located at the Gamma-point or the Y-point and the conduction band minimum at the V-point. This means that CaBi2O4 is an indirect energy gap material. The conduction band is composed of Bi 6p-O 2p interaction. On the other hand, the valence band can be divided into two energy regions ranging from -9.92 to -7.40 eV (lower valence band) and -4.69 to 0 eV (upper valence band). The former is mainly constructed from Bi 6s states interacting slightly with O 2s and 2p states, and the latter consists of 0 2p states hybridizing with Bi 6s and 6p states. The states near the valence band maximum are strongly localized and the mobility of holes generated by band gap excitation is predicted to be fairly low. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2010.01.057

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Potentiometric CO2 sensors based oil NASICON (Na1+xZr2Si2PO12) were fabricated by combining with a Li2CO3-BaCO3 (1:2 in molar ratio) auxiliary phase. The CO2 sensing properties of NASICON (x = 0, 1, 2, 2.75) sensors were investigated under dry condition at 450 degrees C. The electromotive force (EMF) values of NASICON sensors were proportional to the logarithm of CO, concentrations in the range of 250 to 2500 ppm. When exposed to dry air containing 250 ppm CO2, the EMF values of each sensor continuously changed toward a negative potential. From a X-Ray Diffraction (XRD) measurement, it was confirmed that new crystal phases such as Li2ZrO3, ZrO2, Na2Zr(PO4)(2) and Na5Zr(PO4)(3) were formed at the interface between sensing electrode and solid-state electrolyte, because of reaction between Li2CO3 and NASICON. The result of XRD measurement I In suggested that the base-EMF change closely related with the decrease of Li+ activity in auxiliary phase and Na2O activity NASICON. (C)2010 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.118.213

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

TiO(2) particles or casted thin films are treated with plasma CVD using the mixture of tantalum alkoxide and nitrogen gas or copper(II) acetylacetonate to improve the photocatalyst activities of TiO(2) irradiated by visible light. The layer formed on the surface of the TiO(2) after plasma treatment is composed of some species characterized by XPS measurement. The visible-light activity are shown after the plasma CVD treatment to the surface of TiO(2).

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Four kinds of NASICON (Na(1+x)Zr(2)Si(x)P(3-x)O(12), x =1, 1.5, 2 or 2.75)-based CO(2) devices were combined with a Li(2)CO(3)-BaCO(3) (1:2 in molar ratio) auxiliary phase to investigate their CO(2) sensing properties. The EMF values of NASICON devices were correlated linearly with the logarithm of CO(2) concentrations in the range of 250-2500 ppm at 450 degrees C. When exposed to 250 ppm CO(2) for 200 h under dry condition, the EMF of each NASICON device decreased with aging time. To research the cause of the EMF drift, a mixture that consists of NASICON and Li(2)CO(3) was heated at 750 degrees C in air. From X-ray diffraction measurement, it was confirmed that alkali-rich crystal phases such as Li(2)ZrO(3) and Na(5)Zr(PO(4))(3) were formed instead of Na(3)Zr(2)Si(2)PO(12) phase. This Suggests that the EMF drift relates with the formation of alkali-rich crystal phase at the interface between NASICON and auxiliary phase. (C) 2009 Published by Elsevier B.V.

DOI： 10.1016/j.snb.2009.03.040

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

CO(2) sensing characteristics were investigated under dry condition for potentiometric CO(2) sensors: air, Au vertical bar NASICON (Na(1+x)Zr(2)Si(2)PO(12), x=0, 1, 2, 2.75) vertical bar Li(2)CO(3)-BaCO(3), Au, air + CO(2). The electromotive force (EMF) values of each NASICON sensor were linearly increased to the logarithm Of CO(2) concentrations in the range of 250 to 2500 ppm at 450 degrees C. EMF values of each sensor continue to change toward negative potential during the operation exposing to 250 ppm CO(2) under dry condition. For the sensor using NASICON (Na(3.75)Zr(2)Si(2)PO(12)) with rich Na component, base-EMF (EMF value to fix a 250 ppm CO(2)) could become fairly stable. In addition, from the use of a x-ray diffraction (XRD) measurements, the factor of EMF drifts caused the decrease of Na(2)O activity in NASICON by decomposition of NASICON components.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Nitrogen-doped (N-doped) TiO2 particles are prepared by plasma treatment using nitrogen gas and thermal stability of visible light activity in the N-doped TiO2 particles is investigated. The particles are heat treated in either nitrogen or air atmospheres in the range of 373 to 673 K. Photocatalytic activity under visible light irradiation in the N-doped TiO2 particles decreases with increasing heat treatment temperature both in nitrogen and air atmospheres and is almost nonexistent at 673 K. Visible light absorption is conspicuous in the N-doped TiO2 particles after heat treatment in nitrogen atmosphere. Doped nitrogen atoms are removed from the particles by the heat treatment to form oxygen vacancies which cause visible light absorption. On the other hand, visible light absorption decreases with heat treatment in air. The doped nitrogen atoms are substituted with oxygen atoms during heat treatment such that the structure reverts to that of the original TiO2 particles. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2008.03.041

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

TiO2 films are treated using a magnetron nitrogen-plasma apparatus that can generate high density plasma to realize nitrogen-doping. The films are treated for 5 min with nitrogen plasma at a discharge power from 30 to 100 W by a radio frequency generator operating at 13.56 MHz. The plasma treated films show visible light absorption in the range of around 400-500 nm. light absorption above approximately 500 nm is also observed in the film plasma treated at a high discharge power. It is confirmed from N-1s and Ti-2p X-ray photoelectron spectra of the films that Ti-N bonds and oxygen vacancies are formed. Visible light activity of photocatalysis in the film increases with increasing discharge power and then decreases. Such an increase and decrease in the visible light activity are due to the formation of Ti-N bonds and oxygen vacancies, respectively. The visible light activity is improved with the optimum plasma treatment. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2008.05.048

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

ZnO films codoped with Al and N have been prepared by radio frequency magnetron sputtering in an Ar atmosphere, using targets of mixtures of ZnO and AlN powders. The Al-doped ZnO films are transparent, whereas the films codoped with Al and N are colored. The Al and N-concentrations in the colored films are estimated to be 4-7 at.% and 1-2 at.%, respectively. No enhancement of the carrier density is seen in the colored ZnO films, whereas the colored films exhibit lower etching rates of 3-5 nm/s in a 0.1 M HCl solution, in comparison with the Al-doped ZnO films. For the colored film, the anisotropic grain growth occurs, and cubic grains are produced after etching. The low etching rates of the colored films are ascribed to the epitaxial growth of AlN films on the surfaces of ZnO grains, rather than the incorporation of Al-N and Al-O bonds into the ZnO lattice. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2007.09.021

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

The electronic structure of antiferromagnetic Bi2CuO4 is calculated by using generalized gradient approximation considering on-site Coulomb interaction between d-electrons (GGA+U). The GGA+U calculation indicates clearly that the antiferromagnetic phase is the stablest among non-magnetic, ferromagnetic and antiferromagnetic phases. By using U parameter (7.48 eV) and J parameter (0.95 eV), the band gap energy of Bi2CuO4 is calculated to be ca. 2.4 eV, which is comparable to the experimental one. The valence band maximum is approximately located at the X-point and the conduction band minimum at the Gamma-point. This means that antiferromagnetic Bi2CuO4 is an indirect energy gap material. The calculated total density of states of Bi2CuO4 Well corresponds to the state density experimentally deduced by x-ray photoelectron and electron-energy-loss spectroscopy. Also, it is found from the partial density of states analysis that the top of the valence band is mainly formed by O 2p orbitals, whereas the lower conduction band mainly consists of Cu 3d(x)(2)-(2)(y) orbitals. The magnetic moment at Cu sites is calculated to be 0.72 mu(B), which is close to experimental values. (c) 2008 The Ceramic Society of Japan. All rights reserved.

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2109/jcersj2.116.589

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

NASICON (Na3Zr2Si2PO12)-based potentiometric NO2 devices, such as Au-attached, (ITO, NaNO2)-attached and (ITO, NaNO2-Li2CO3)-attached types, were fabricated and their NO2 sensing properties were investigated in the range of 2-7 ppm NO2 under 1-50% relative humidity (RH) between 30 degrees C and 150 degrees C. The Au-attached device had a NO2 sensing capability under wet condition (30% RH) without an auxiliary phase, although it showed no EMF response under dry condition (below 1% RH). This result suggests that NO2 sensing reaction of the device is closely related with water vapor. To enlarge the NO2 sensitivity at room temperature, a (metal, nitrite)-attached device was fabricated by combining ITO with NaNO2. The EMF change of the (ITO, NaNO2)-attached device was estimated to be 43.6 mV under 30% RH in the range of 2-7 ppm NO2 and enlarged remarkably in comparison with 17.7 mV of the Au-attached device. However, the NO2 sensitivity of the (ITO, NaNO2)-attached device was riot only fluctuated by the change of relative humidity, but the EMF values shifted upward with increasing humidity at a fixed NO2 concentration. It is considered that this originates from the fact that a nitrite auxiliary phase is easy to dissolve in water. Therefore, Li2CO3 with durability to water vapor was melted together with NaNO2 and used as the auxiliary phase of the (ITO, NaNO2)-attached device. As the result, it was found that the EMF change of the (ITO, NaNO2-Li2CO3)-attached device was constant almost without depending on humidity. The EMF values of the device were also proportional to the logarithm of NO2 concentration and well consistent with theoretical values obtained from the Nernstian equation. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2007.07.142

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

ZnO films prepared from the ZnO target containing 2% AIN are transparent irrespective of radio frequency (RF) power. The obtained ZnO films have the carrier density of 3.8 x 10(20) cm(-3) or less and the low mobility of 5.3-7.8 cm(2)/(V s). In the case of 5% AIN target, ZnO films prepared at 40, 60 and 80 Ware transparent, whereas ZnO films prepared at 100 and 120 Ware colored. As RF power increases from 40 to 120 W, the carrier density increases straightforwardly up to 5.5 x 10(20) cm(-3) at 100 Wand is oppositely reduced to 3.2 x 10(20) cm(-3) at 120 W. In the case of 10% AIN target, ZnO films prepared at 60 W or more are colored, and have the carrier density of 4 x 10(20) cm(-3) or less. The N-concentration in these colored films is estimated to be 1% or less. The Al-concentration in the ZnO films prepared from the 5 and 10% AIN targets is higher than 2%. The carrier density of the ZnO films containing Al and N atoms is nearly equal to that of ZnO films doped with Al atoms alone. There is no evidence in supporting the enhancement of the carrier density via the formation of N-AlxZn4-x clusters (4 >= x >= 2). (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2006.11.019

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The electronic structure of S-doped TiO2 with an optimized anatase structure was calculated within the framework of the density functional theory (DFT). For the calculation we built four kinds of supercells; type-A and B supercells consist of 12 and 48 atoms and a centered Ti atom is substituted for an S atom, while type-C and D supercells consist of 12 and 48 atoms and a centered 0 atom is substituted for an S atom. The supercells (type-B and D) were employed to adjust the S-concentration in TiO2 to an experimental value of a few %. The changes of the lattice parameters are not significant in the type-A and B supercells. The phase transition from the tetragonal to the orthorhombic occurs in the type-C and D supercells. In the small supercell (type-A), S-related states are located in the range of -1.6 to 0 eV, and the S-states are band-like. In contrast, in the large supercell (type-B), S-related states appeared at about 0.9 eV above the top of the valence band, and the S-states are atomic-like. The localization of the S-related states is remarkable in the type-B supercell. In the type-D supercell, the S-related states were merged with the top of the valence band, and as a result the band-gap energy is narrowed by 0.7 eV. Despite a low S-concentration (3%) in the type-D supercell, the S-related states are somewhat band-like. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jpcs.2006.10.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Vacuum Society of Japan  

If TiO2 particles are used as components of paint without any surface modification, binding resin of the paint will be easily decomposed by the photocatalytic activity of the particles. In this work, plasma polymerization of octamethylcyclotetrasiloxane as a siloxane monomer is tried to form thin layer stable to the photocatalytic activity on the surface of TiO2 particles. The plasma-polymerized layer containing Si-O and Si-C bonds is formed on the surface of the particles and shows stability to the photocatalytic activity of TiO2. The particles surface-modified with the plasma polymerization exhibit visiblelight activity. The visible-light activity is originated from carbon doping which brings about in the particles during the plasma polymerization, and is thermally stable to be maintained after annealing at 673 K.

DOI： 10.3131/jvsj.50.629

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記述言語：日本語   掲載種別：研究論文（国際会議プロシーディングス）  

Antiphotocatalytic and thin layer should be formed on the surface of TiO2 particles by plasma polymerization to depress photocatalytic decomposition of binding resin, when the particles are used as components of paint. The particles were plasma-polymerized with octamethylcyclotetrasiloxane as a monomer. The particles were doped with carbons to form Ti-C bonds during the plasma polymerization. The carbon-doped particles revealed visible-light absorption and methylene blue molecules adsorbed on the surface of the particles were decomposed with visible-light irradiation. Composition ratio of Si/Ti at the surface of the plasma- polymerized particles was a little decreased by heat-treating at 673 K in air. Infrared absorption associated with Si-CH 3 stretching vibration disappeared substantially to be similar to silica-like and silicon carbide-like structure after the heat treatment. The carbon-doping and the visible-light activity in the particles were almost maintained after the heat treatment.

Scopus

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TRANS TECH PUBLICATIONS LTD  

ZnO films doped with Li and Cl atoms have been prepared by organometallic chemical vapor deposition method. In photoluminescence spectra of the doped ZnO films, strong emission appears at 376 nm which is slightly longer than that of free-excitons. As excitation intensity increases, a peak wavelength of the emission is shifted toward a shorter value. The emission near band-gap edge is assigned to radiative recombination via Li-Cl pairs.

DOI： 10.4028/0-87849-982-2.185

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELECTROCHEMICAL SOC JAPAN  

NASICON (Na3Zr2Si2PO12)-based potentiometric NO2 devices, such as an Au-attached and an (ITO, NaNO2)-attached types, were prepared and their NO2 sensing properties investigated in the range of 1.9 to 6.7 ppm NO2 diluted with air at 30 degrees C. The Au-attached device was found to have a NO2 sensing capability under a humidity condition (30% RH) without any auxiliary phase, although it showed no EMF response under a dry condition (below 1% RH). This experimental result suggests that NO2 sensing reaction of the device is closely related with water vapor. To enhance the NO2 sensitivity of the NASICON-based. device, the (ITO, NaNO2)-attached device was therefore fabricated. As the result, the AEMF of the (ITO, NaNO2)-attached device was estimated to be 43.6 mV under 30% RH in the range of 1.9 - 6.7 ppm NO2, and improved more remarkably in comparison with 17.7 mV of the Au-attached device.

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

The improvement for the deterioration of CO2 sensing properties in lower humidity condition was attempted to a NASICON-based potentiometric CO2 device operative at room temperature. To optimize the sensing electrode, the device was fabricated by using ITO powders with a large specific surface area and by using a mixture of ITO and basic oxide powders. Although CO2 sensing properties of the device were markedly improved by applying the above ideas in lower humidity condition, it was confirmed that the basic EMF drifts with changing the humidity conditions. Further, to find out the appreciate reference electrode material, the thermal and chemical stabilities were examined by XRD measurement for three kinds of oxides such as Li 0.62CoO2, Na0.6CoO2 and Li 2TiO3. As the results, Na0.6CoO2 and Li2TiO3 were much stabler than Li0.62CoO 2 thermally and chemically. It was also found that Li 2TiO3 has a poor electric conductivity. Therefore, Na 0.6CoO2 is the most suitable material for the reference electrode of the NASICON-based device operative at room temperature. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2004.12.119

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

The Dion-Jacobson series of triple-layered perovskite tantalates (MCa2Ta3O10, M = Cs, Na, H, and C6H13-NH3) were synthesized to evaluate their photocatalytic activity for overall water splitting to evolve H-2/O-2 under UV irradiation. The photocatalytic activity was susceptible to the hydration of interlayer space. The hydrous Na phase exhibited much higher activity (H-2: 308 mu mol(.)h(-1)) compared to the anhydrous Cs phase (24 mu mol(.)h(-1)) and the hydrous H phase (22 mu mol(.)h(-1)) in the presence of 0.5 wt % Ni impregnated. H2O/D2O isotopic experiment suggested that the hydrated interlayer plays as an active site for water splitting, where the high mobility of water molecule in the interlayer should correlate with the total photocatalytic activity. The FLAPW electronic structure calculation demonstrated that the terminating oxygen site, O(4), which faces to the interlayer space, contributes largely to the top of the valence band. Judging from comparison with the double-layered tantalates, MLaTa2O7, in our previous study, the contribution of terminating oxygen site to the band structure is supposed to depend on the number of perovskite layers.

DOI： 10.1021/jp044833d

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記述言語：日本語   掲載種別：研究論文（国際会議プロシーディングス）  

Since Gratzel and coworkers developed a new type solar cell based on the nanocrystalline titanium dioxide (TiO2) electrode sensitized to visible light with dye molecules, which had a high overall energy conversion efficiency of 10%, the goal of efficient solar cells has focused on dye-sensitized photochemical solar cells. For the performance of the cell, the porous surface nanostructure of the TiO2 electrode is very important. In this paper, molecular weight, M.W. and weight fraction dependence of a polymer organic-medium on the nanostructure of TiO2 electrode and the photoelectrochemical performance of the dye-sensitized solar cell has been investigated. It has confirmed that polyethylene glycol (PEG) with high M.W. or 40wt% TiO2 fraction is a promising alternative polymer organic-medium leading to a higher open-circuit voltage
short-circuit current density and a larger fill factor and thus a higher power output.

Scopus

記述言語：日本語   掲載種別：研究論文（国際会議プロシーディングス）  

Since Gratzel and coworkers developed a new type solar cell based on the nanocrystalline titanium dioxide (TiO2) electrode sensitized to visible light with dye molecules, which had a high overall energy conversion efficiency of 10%, the goal of efficient solar cells has focused on dye-sensitized photochemical solar cells. For the performance of the cell, the porous surface nanostructure of the TiO2 electrode is very important. In this paper, weight fraction and molecular weight, M.W. dependence of a polymer organic-medium on the nanostructure of TiO2 electrode and the photoelectrochemical performance of the dye-sensitized solar cell has been investigated. It has confirmed that polyethylene glycol (PEG) with 40wt% TiO2 fraction or high M.W. is a promising alternative polymer organic-medium leading to a higher open-circuit voltage
short-circuit current density and a larger fill factor and thus a higher power output.

Scopus

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

When TiO2 particles are used as a component of paint without any surface modification, binding resin will be easily decomposed by photocatalytic property of the particles. In this work, it is tried that thin layer having silica-like structure is formed on the surface of TiO2 particles by plasma polymerization. The particles were pretreated with argon plasma and then were plasma-polymerized with octamethylcyclotetrasiloxane as a monomer. Thin layer composed of Si-O bonds was formed on the surface of the particles. Ratio of surface element, Si/Ti in the particles was increased with increasing plasma polymerization time. The particles surface-modified with the plasma polymerization revealed visible-light absorption and methylene blue molecules adsorbed on the surface of the particles were decomposed with visible-light irradiation. It is presumed that C doping or Si doping takes place in process of the plasma polymerization.

Scopus

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELECTROCHEMICAL SOC JAPAN  

The electronic structure of TiO2 with brookite structure is calculated within the framework of the density functional theory (DFT). Calculated lattice constants are in excellent agreement with experimental values. Brookite is predicted to be a material with a direct band gap at the F point. The valence band with the width ca. 4.8 eV is mainly constructed from O 2p orbitals, whereas the lower conduction band mainly Ti 3d orbitals.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The electronic structures of undoped and N-doped InTaO4 with optimized structures are calculated within the framework of the density functional theory. Calculated lattice constants are in excellent agreement with experimental values, within a difference of 2%. The valence band maximum (VBM) is located near the middle point on the ZD line and the conduction band minimum (CBM) near the middle point on the DX line. This means that InTaO4 is an indirect-gap material and a minimum theoretical gap between VBM and CBM is ca. 3.7 eV. The valence band in the range from -6.0 to 0 eV mainly consists of 0 2p orbitals, where In 4d5s5p and Ta 5d orbitals are slightly hybridized with 0 2p orbitals. On the other hand, the conduction band below 5.5 eV is mainly composed of the Ta 5d orbitals and the contributions of In and 0 orbitals are small. The band gap of N-doped InTaO4 decreases by. 0.3 eV than that of undoped InTaO4, because new gap states originating from N 2p orbitals appear near the top of the valence band. This result indicates that doping of N atoms into metal oxides is a useful method to develop photocatalysts sensitive to visible light. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0022-3697(03)00283-X

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Electronic structure of NaCl type LiInO2 was compared experimentally and theoretically with that of alpha-NaFeO2 type NaInO2 to clarify the influences of Li-In direct interaction peculiar to LiInO2. Ultraviolet-visible diffuse reflectance spectrum of LiInO2, with the onset of absorption at 3.7 eV, was rather more simple than that of NaInO2 accompanied by two small peaks in the band gap of 3.7 eV. Discrete variational-Xalpha calculations for the [Li10In9O44](51-) and [Na7In12O44](45-) model clusters depicted well the features of absorption spectra of LiInO2 and alpha-NaInO2, respectively. The calculations also revealed that higher valence bands of LiInO2 and NaInO2 were dominated, respectively, by the Li 2s-In 5s bonding orbital with a large overlap population and the Na 3s,p-O 2p bonding orbital with a small overlap population, however, lower conduction bands in both LiInO2 and NaInO2 were formed by the In 5s-O 2p antibonding orbital. The experimental valence band spectrum of LiInO2, simply peaked at similar to4 eV below the valence band maximum, can be ascribed to overlapping of the Li 2s-In 5s bonding orbital with the In 5p-O 2p bonding orbital at around -3 eV in the density of states. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0925-8388(03)00179-8

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

From a first-principles band calculation, InTaO4 is predicted to be an indirect-gap material, because the valence band maximum (VBM) is located in the middle point on the ZD line and the conduction band minimum (CBM) in the middle point on the DX line. The valence band with the width ca. 6.0 eV is mainly constructed from O 2p orbitals hybridized with In4d5s5p and Ta5d orbitals, whereas the lower conduction band is constructed from Ta5d orbitals.

DOI： 10.1246/cl.2003.64

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

Layered lanthanide tantalates and their ion-exchanged phases (MLnTa(2)O(7), M = Cs, Rb, Na, and H; Ln = La, Pr, Nd, and Sm) were prepared to evaluate their photocatalytic activity for water splitting under UV irradiation. The optical band gap energy was dependent on the lanthanide, Ln, but negligibly affected by the monovalent interlayer cations, M. By contrast, the photocatalytic activity was strongly affected by not only Ln but also M; the highest activity was attained by a series of M = Rb with a sequence of Ln: Nd > Sm > La > Pr. The effect of Ln can be explained by the energy level and hybridization of the Ln 4f band, which was discussed based on the results of electronic structure calculations in our previous work. The ion exchanged phases ( M = Na and H) having deformed hydrous layer structure were less active compared to anhydrous Rb and Cs phases, whereas the NiOx loading of the Na phase greatly enhances the activity. It seems that the high mobility of water molecules between the layers allows the interlayer sites to behave as active sites for the photocatalytic reaction over NiOx-loaded catalysts.

DOI： 10.1039/b301938c

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J-GLOBAL

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

The electronic structure of strontium aluminate, SrAl2O4, is calculated by using the scalar-relativistic full potential linearized augmented plane wave (FLAPW) method. SrAI(2)O(4) is predicted to be an indirect-gap material, since the valence band maximum locates near Z point and the conduction band minimum at F point. The valence band with the width ca. 5.3 eV is mainly constructed from 0 2p orbitals, where AI 3s3p and Sr 5s5p slightly hybridize with 0 2p, and the lower conduction band from Sr 5s orbitals.

DOI： 10.1246/cl.2002.700

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J-GLOBAL

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

The electronic structures of ZnO doped with group III elements (B, Al, Ga and In) are calculated by using the discrete variational Xalpha method of clusters. For ZnO doped with group III elements, new states originating from group III elements appear in the band gap. The depth energy of impurity-related states is the shallowest for Al and is the deepest for B.

DOI： 10.1246/cl.2002.580

Web of Science

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

The electronic structure of ZnSb2O6 is calculated by using the FLAPW method and the DV-X alpha method. The valence band with the width of ca. 10.5 eV is roughly classified into the two bands, where O 2p orbitals are dominant and hybridize with Zn 3d and Sb 5s orbitals. On the other hand, the lower conduction band is mainly constructed from Sb 5s orbitals which have large spatial extent. Therefore, ZnSb2O6 crystal is expected to have large electron mobility with doping carriers.

DOI： 10.1246/cl.2001.1010

Web of Science

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

The electronic structures of ZnGa2O4 and ZnGa2O4:Mn are calculated by the discrete variational X alpha method on model clusters. For ZnGa2O4, it is found that Zn-O and Ga-O bondings are not perfectly ionic but partially covalent. When a central Zn atom of the cluster is replaced with a Mn atom, the new energy states originating from Mn 3d orbitals appear in the energy gap. The energy levels of t(2) up-spin states and e down-spin states seem to relate to the green emission.

DOI： 10.1246/cl.2001.664

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Doping of lithium into indium sesqui-oxide (In2O3) brought about an increase in the lattice constant of cubic cell from 10.116 to 10.163 Å and a decrease in the optical absorption energy from 2.72 to 2.68 eV with increasing the nominal molar ratio x (=[Li]/[In2O3])&lt
0.5. Enlargement of the lattice constant obeying the Vegard's law suggests that the doped Li atoms occupied interstitial sites of In2O3 crystal. Tight-binding (TB) band-structure calculations with two Li atoms at 8a sites and those at 16c sites of the crystal showed decrements in energy splitting between the valence and conduction bands by 0.2 and 0.1 eV, respectively, and supported the observed decrements of the optical absorption energy in In2O3:Lix. First-principles molecular-orbital (MO) calculations with clusters for Li atoms at 8a sites showed similar result to the TB calculation. Changes in the X-ray photoelectron valence band spectra of the In2O3:Lix (x=0, 0.2, and 0.5) agreed with those in the density of states expected from the TB and MO calculations. Non-linear current-voltage characteristics were due to the surface states and surface band bending observed in the valence band spectra. © 2001 Elsevier Science B.V.

DOI： 10.1016/S0925-8388(01)01019-2

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/jp004297z

J-GLOBAL

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

X-ray photoemission spectroscopy (XPS) measurements were performed on SrTiO3 and BaTiO3 single crystals with monochromated Al K alpha radiation. Valence band (VB) spectra of as-fractured SrTiO3 and BaTiO3 crystals exhibit two peaks arising from the O 2p pi and O 2p sigma bonding orbitals, From a partial density of states (PDOS) calculation, it is found that O 2p orbitals fairly hybridize with Ba 5p orbitals, while do not almost hybridize with atomic orbitals of Sr atom. This indicates that the nature of the chemical bonding of Ba-O in BaTiO3 is more covalent than that of Sr-O in SrTiO3.

DOI： 10.2109/jcersj.108.1262_952

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Mining and Materials Processing Institute of Japan  

Electronic structure of ZnSb₂O₆ was investigated using the discrete variational (DV)-Xα method on the model cluster [Zn₅Sb₁₀O₅₆] ^52-. In the calculation, the band gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied MO (LUMO) was 3.80 eV. In the valence band, Sb-O and Zn-O bondings are considered to be not perfectly ionic but partially covalent because of the hybridization of O 2p orbitals with Sb 5sp and Zn 3d orbitals. Furthermore, ZnSb₂O₆ crystal is expected to have a large electron mobility because Sb 5s orbitals are dominant at the bottom of the conduction band. The calculated net charges are +1.48e for Zn, -1.20e for O and +3.02e for Sb. The bond overlap populations are calculated to be 0.09 and 0.29 for Zn-O and Sb-O bondings, respectively. These results show that Sb-O bonding is more covalent than Zn-O bonding in ZnSb₂O₆ crystal.<br>

DOI： 10.2473/shigentosozai.116.795

CiNii Books

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人日本セラミックス協会  

Perovskite-type LnFeO_3(Ln=La, Sm, Dy) powders were prepared by thermal decomposition of cyanidebridged heteronuclear complexes and their gas sensing properties to C_3H_6 were investigated. As a result, it was found that SmFeO_3 has the highest sensitivities to C_3H_6 among the perovskite oxides examined. By adding a small amount of Pd to SmFeO_3, gas-sensing properties such as gas sensitivity and response time were largely enhanced.

DOI： 10.2109/jcersj.108.1259_681

CiNii Books

J-GLOBAL

担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Mining and Materials Processing Institute of Japan  

The electronic structure of BaTiS₃ was investigated using a discrete-variational Xα (DV-X α) method on the model cluster. In the calculation of [Ba₆Ti₃S₄₈]^72- cluster, the band gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was 0.98 eV, which was much smaller than that of ionic crystal, BaTiO₃. In the valence band region, S 3p orbitals hybridized with Ti 3d orbitals, while not with atomic orbitals of Ba atom. Net charges calculated for the [Ba₆Ti₃S₄₈]^72- cluster were + 1.911 for Ba, + 0.750 for Ti and -0.682 for S, respectively. Furthermore, the bond overlap population of Ti-S bond was very large, compared with the Ti-Ti and Ba-S bonds. These results indicate that the covalent interaction between Ti and S atoms plays a dominant role on chemical bond of BaTiS₃ crystal. <br>

DOI： 10.2473/shigentosozai.116.532

CiNii Books

J-GLOBAL

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELECTROCHEMICAL SOC JAPAN  

The electronic structures of ZnO, Li-doped ZnO and N-doped ZnO are calculated using the discrete variational Xa: method on model clusters. For ZnO, it is found that the Zn-O bonding is not perfectly ionic but partially covalent because of the hybridization between Zn 3d and O 2p orbitals in the valence band. When a Zn atom of the cluster is replaced with a Li atom, the width of the valence band is expanded than that of the ZnO cluster, and at the same time the energy gap between HOMO and LUMO decreases. On the other hand, the new energy states originating from N 2p orbitals in the energy gap are formed for N-doped ZnO.

Web of Science

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

For undoped-SrTiO3 and La-doped SrTiO3 single crystals, X-ray photoemission spectroscopy (XPS) measurements were performed with monochromated Al Ka radiation. Valence band (VB) spectra of as-fractured SrTiO3 exhibit two peaks, Fl and P2, arising from the O 2p pi and O 2p sigma bonding orbitals, respectively. Upon adding 3.0 atm% of La to SrTiO3, the valley between P1 and P2 disappears in the VB spectrum, Calculated VB spectra obtained from a molecular orbital calculation reproduce well the experimental XPS spectra for the samples.

DOI： 10.2109/jcersj.108.1257_518

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J-GLOBAL

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

The electronic structures of NaInO2 and NaInS2 are calculated by using the discrete variational X alpha method on model clusters. For NaInO2, it is found that the In-O bonding is not perfectly ionic but partially covalent because of the hybridization between O 2s, 2p and In 5s, 5p orbitals in the electron-occupied band. However, the overlapping of Na 3s, 3p orbitals with O 2s, 2p orbitals is very weak. On the other hand, Na 3s, 3p orbitals of NaInS2 relatively hybridize with S 3s, 3p orbitals, not only In 5s and 5p orbitals. These results show that the nature of the chemical properties of NaInS2 is more covalent, compared with NaInO2.

DOI： 10.1246/cl.2000.8

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J-GLOBAL

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

NaInO2 and NaInS2 with alpha-NaFeO2 layer type structure have been prepared and characterized by X-ray photoelectron spectroscopy to clarify the role of the anions in the electronic structures of the compounds. The In 3d(5/2) binding energy for both compounds was the same, though the Na 1s binding energy of NaInO2 was larger than that of NaInS2 by 0.4 eV. The change in the Na Auger parameter, defined as the sum of Na 1s binding energy and KLL Auger kinetic energy, suggests that the difference in extra-atomic relaxation energy between the compounds causes the Na 1s binding energy shift. Discrete variational-X alpha model cluster calculations for NaInO2 and NaInS2 mirrored the experimental valence band spectra and the difference of 0.5 eV in optical absorption energy of the compounds. The cluster calculation revealed that in NaInO2 the highest occupied level is formed by an antibonding Na-O bond, whereas that in NaInS2 is formed by a bonding Na-S bond. The covalent Na-S bond decreases the extra-atomic relaxation energy for Na 1s electron emission from NaInS2.

DOI： 10.1039/a908505j

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN J APPLIED PHYSICS  

The electronic structure of a Pd-adsorbed SnO2 (001) surface is calculated using a semiempirical tight-binding method. When a Pd atom bridges two oxygen atoms on the SnO2 (001) surface, bonding and antibonding states arising from the admixture of Pd 4d and O 2p orbitals are formed around -15 eV and -8.35 eV. The energy levels of these bonding and antibonding states are overlapped with those of the valence and conduction bands. Nonbonding states originating from Pd 4d are calculated to be -9.2 eV and are located near the bottom of the conduction band of SnO2. The Fermi level of -8.37 eV is pinned at the nonbonding states with a large state density. When two Pd atoms are bound to two oxygen atoms on SnO2 (001), Pd-related states exhibit a bandlike character in spite of less than one monolayer coverage.

DOI： 10.1143/JJAP.38.4993

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J-GLOBAL

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHEMICAL SOC JAPAN  

Lithium-doped indium oxide crystals (In2O3 : Li-x, x=0-1.0) were synthesized by calcination in flowing oxygen of dried powders from aqueous solutions of InCl3 with Li. Only the peaks from cubic In2O3 crystal were observed in X-ray diffraction (XD). The lattice constant increased from 10.116 to 10.163 A, and the optical absorption energy decreased from 2.72 to 2.68 eV with increasing x in In2O3:Li-x. The lattice constant estimated by XD and the optical absorption edge in UV-visible absorption spectrometry remained at constants (10.163 Angstrom and 2.68 eV) in the region of x=0.5-1.0. Tight-binding (TB) band-structure calculations were performed for studying changes in the electronic structure with Li doping. The calculated energy splitting between the top of the valence band and the bottom of the conduction band decreased by Li doping at the empty sites (8a and 16c) of pure In2O3 crystal, which was consistent with the experimental decrements of the absorption energy with x in In2O3:Li-x. Changes in the valence band spectra by X-ray photoelectron spectroscopy of the In2O3:Li-x(x=0, 0.2 and 1.0) agree with that in the density of states by the TB calculation for two Li atoms doped at 8a or at 16c sites of In2O3 crystal. Doping of Li atoms into the interstitial sites affects both on the valence band and the conduction band minimum of the In2O3 crystal.

DOI： 10.1246/nikkashi.1999.323

Web of Science

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

Lithium-doped indium oxide crystals (In2O3 : Lix, x=0-1.0) were synthesized by calcination in flowing oxygen of dried powders from aqueous solutions of InCl3 with Li. Only the peaks from cubic In2O3 crystal were observed in X-ray diffraction (XD). The lattice constant increased from 10.116 to 10.163 Å, and the optical absorption energy decreased from 2.72 to 2.68 eV with increasing x in In2O3 : Lix. The lattice constant estimated by XD and the optical absorption edge in UV-visible absorption spectrometry remained at constants (10.163 Å and 2.68 eV) in the region of x=0.5-1.0. Tight-binding (TB) band-structure calculations were performed for studying changes in the electronic structure with Li doping. The calculated energy splitting between the top of the valence band and the bottom of the conduction band decreased by Li doping at the empty sites (8a and 16c) of pure In2O3 crystal, which was consistent with the experimental decrements of the absorption energy with x in In2O3 : Lix. Changes in the valence band spectra by X-ray photoelectron spectroscopy of the In2O3 : Lix(x=0, 0.2 and 1.0) agree with that in the density of states by the TB calculation for two Li atoms doped at 8a or at 16c sites of In2O3 crystal. Doping of Li atoms into the interstitial sites affects both on the valence band and the conduction band minimum of the In2O3 crystal.

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：社団法人日本セラミックス協会  

Heteronuclear complexes of Ln[Fe_xCo_&lt;1-x&gt;(CN)_6]・4H_2O (Ln=Pr-Yb) were synthesized and their thermal decomposition products were investigated. Thermal decomposition of the complexes results in the formation of perovskite-type oxides for Ln=Pr-Gd even at 800℃. The lattice parameters, a-, b- and c-lattice constants (crystal system: orthorhombic) increase linearly with the ratio of Fe/Co for the perovskite-type oxide. For Ln=Dy through Yb, the Ln_2O_3 phase is observed as the major product for x=0, but its content decreased with an increase in the Fe content; however, a single phase of the perovskite-type oxide was not formed for x=1. The perovskite-type structure for the Fe systems is easier to form compared with the Co systems. We clarified that the formation of the perovskite-type oxide is mainly affected by the ionic radius of the Ln^&lt;3+&gt; ion and the T^&lt;3+&gt; ion (T=Fe or Co).

DOI： 10.2109/jcersj.105.963

CiNii Books

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CHAPMAN HALL LTD  

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER CHEMICAL SOC  

Resistance and capacitance of the ZnO-SiO2-Au device appreciably respond to changes in O-2 partial pressure under strong UV illumination (10 mW/cm(2)). From complex impedance plots under the strong UV illumination, values of resistance of the ZnO film are estimated to be 300 and 50 k Omega in Oz and in Ar, respectively, and values of resistance of the ZnO-SiO2 interface at 0 V are estimated to be 1000 and 280 k Omega in O-2 and in Ar, respectively. Plots of Cp(-2) vs V in the dark, where C-p is the capacitance of the ZnO-SiO2 interface and V is a bias voltage, indicate that the band bending in O-2 is larger than that in Ar by 0.25 eV;and that the carrier density (5 x 10(17) cm(-3)) of the ZnO film in O-2 is the same as in Ar. When the UV illumination is turned off, a remarkable recovery of resistance measured at 100 Hz is observed at -2 and 0 V in Oz, while no recovery is observed in Ar. The response of the resistances of both the ZnO film and the ZnO-SiO2 interface to changes in the Oz partial pressure is ascribed to a change in the band bending caused by adsorption and photon-stimulated desorption of oxygen.

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Ceramic Soc of Japan  

Thick Zn2SnO4 films have the highest sensitivities to NO2 among the examined complex oxides with spinel structure. Although the NO2gas sensitivities of thick Zn2SnO4 films decrease with increasing temperature, high sensitivities are obtained in the temperature range of 573 to 673 K. The sensitivities of the present Zn2SnO4 films are comparable to those of NO2-sensitive oxides such as WO3 and ZnO.

DOI： 10.2109/jcersj.103.302

Scopus

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電気化学会  

CiNii Books

記述言語：英語   掲載種別：研究論文（学術雑誌）  

CiNii Books

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE SA  

Model cluster calculations by discrete variational-X alpha method for the Fe3+ ions at 8b and 24d sites of the In2O3 crystal lattice demonstrated that the density of states of the Fe3+ 3d electrons located around the center of the band gap, and the spin density of states for the Fe3+ ions at 8b and 24d sites are asymmetric. For Fe-doped In2O3 powders, we found a cusp at approximate to 30 K overlapping cluster glass behavior in dc susceptibility, though the Cusp showed no frequency dependence in ac susceptibility. The cusp at approximate to 30 K for the Fe-doped In2O3 powders can be attributed to superexchange interactions between Fe3+ ions substituted for In3+ ions of the In2O3 crystal lattice. (c) 2005 Elsevier B.V All rights reserved.

DOI： 10.1016/j.tsf.2005.10.022

Web of Science

J-GLOBAL

担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Doping of Cu to In2O3 brought about growth of a new state in the bandgap and decrement of the bandgap energy with an increase of the nominal molar ratio x( = [Cu]/[In2O3]&lt
1) in the ultraviolet-visible (UV-vis) optical absorption spectra. A superconducting quantum interference device magnetometer was used for magnetic susceptibility measurement. The sample x = 0.5 showed antiferromagnetism with Neel temperature of ∼30 K. In addition to the antiferromagnetism, paramagnetic behavior was also observed for the sample x = 1. First-principles molecular-orbital calculation with a model cluster for Cu2+ ion at the 8a site of the In2O3 crystal showed the density of states (DOS) mirroring the new in-gap state accompanied with the narrowing energy gap. In the model cluster, calculations of Cu2+ ions for the 8a and 16c sites showed the asymmetric and symmetric Cu 3d spin DOS corresponding to the antiferromagnetism and paramagnetism, respectively. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0925-8388(01)01760-1

Scopus

記述言語：日本語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：日本語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：口頭発表（一般）  

会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：日本語   会議種別：ポスター発表  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：口頭発表（一般）  

記述言語：英語   会議種別：ポスター発表  

記述言語：英語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：ポスター発表  

会議種別：口頭発表（一般）  

会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：日本セラミックス協会  

CiNii Books

担当区分：最終著者,　責任著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）   出版者・発行元：北九州工業高等専門学校  

CiNii Books

担当区分：最終著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）   出版者・発行元：北九州工業高等専門学校  

CiNii Books

担当区分：最終著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）   出版者・発行元：北九州工業高等専門学校  

CiNii Books

担当区分：最終著者   記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）   出版者・発行元：電気化学会化学センサ研究会  

担当区分：最終著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（大学，研究機関紀要）  

担当区分：最終著者   記述言語：日本語   出版者・発行元：電気化学会化学センサ研究会  

担当区分：責任著者   記述言語：英語   出版者・発行元：TRANS TECH PUBLICATIONS LTD  

Molecular orbital (MO) calculations were carried out by the DV-Xalpha method to clarify the effect of an impurity on the electronic structures of ZnGa2O4 crystal. In the calculation for M-doped ZnGa2O4 (M being one of the following metals: Mn, Fe, Co, Ni), the new energy states originating from M 3d orbitals appear in the band gap. The gap states split into two energies; the lower state is doubly degenerate c states, the higher one being triply degenerate t(2) states, as predicted by the ligand field theory. These levels tend to decrease in energy as the atomic number of the transition metal ion increases. Furthermore, M-O bonding becomes more covalent with increasing the atomic number of the transition metal ion.

Web of Science

担当区分：筆頭著者,　責任著者   記述言語：英語  

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

記述言語：英語   出版者・発行元：愛媛大学  

CiNii Books

記述言語：英語  

記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）