受賞区分：国内外の国際的学術賞  受賞国：ドイツ連邦共和国

Fully funded 4 years Ph.D. Scholarship to study at Jacob University Bremen, Germany

受賞区分：国内外の国際的学術賞  受賞国：オーストリア共和国

Fully funded scholarship by the European Union for exchange master studies in Nanophysics program at the University of Graz, Austria from Sep.2010 to July 2011

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）  

It has been extremely difficult for nanodiamond composite (NDC) films to be deposited on Ti due to a large thermal expansion coefficient difference. The native oxide layer on Ti is another problem preventing the appropriate adhesion of NDC films and subsequent delamination. In this work, innovative room temperature adhesion of 3 μm NDC films with 54 GPa hardness on Ti substrates was accomplished via a hybrid system of ion etching gun and coaxial arc plasma deposition (CAPD). Ar+ plasma etching is capable to terminate the superficial TiO 2 layer and manipulates substrate morphology during CAPD provides instantaneous deposition of NDC films at room temperature.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1080/21663831.2022.2083457

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In this study, we employed an authentic process for the device fabrication of diamond detectors, wherein thin, highly conductive surface layers were processed in bulk diamond substrate using a nanosecond-pulsed excimer laser with liquid-immersion irradiation. The incorporation of high-concentration phosphorus dopants at 40 nm under the irradiated surface characterized the irradiated areas with much lower electrical resistivity, which was adequate for demonstrating ohmic contacts even with the tungsten probe heads at room temperature.

DOI： https://doi.org/10.1016/j.mssp.2021.106370

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1021/acsami.0c18435

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Heterojunction diodes are constructed by growing n-type (nitrogen-doped) ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films onto p-type Si substrates in nitrogen and hydrogen mixed-gases by coaxial arc plasma deposition. The fabricated heterojunctions are analyzed regarding their film morphology and electrical properties. The complex structure of UNCD/a-C:H films, which consists of nano-sized-sp3 diamond grains and sp2-grain boundaries (GBs), makes it difficult to separate their contribution to electrical conductivity of the films using conventional characterization methods. In this paper we characterize the n-type UNCD/p-type Si heterojunction diode by employing impedance spectroscopy method, which can isolate the differing components that contribute to the overall conductivity of the film. The impedance spectroscopy is measured in the frequency range of 100 Hz to 2 MHz, with AC small signal superimpose on DC bias voltage in the range of 0–1 V. The influence of the bias on UNCD grains and GBs contribution to resistance and capacitance of UNCD/a-C:H film and n-UNCD/p-Si heterojunction is investigated by equivalent circuit model using fitting of the impedance data. The results revealed that the electrical conductivity is mainly controlled by the GBs rather than the UNCD grains. Furthermore, the extracted value of dielectric constant of N-doped UNCD/a-C:H film is found to be comparable with that of microcrystalline diamond, which indicates the capacitance contribution in the device is mainly originated from the UNCD grains. This study demonstrates capability of impedance spectroscopy to provide an obvious separated contribution of sp3 and sp2 bonded carbons to the electrical conductivity in their coexistence materials.

DOI： https://doi.org/10.1088/1402-4896/aba97e

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： DOI 10.35848/1882-0786/abb871

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ultrananocrystalline diamond/hydrogenated amorphous carbon films were synthesized by coaxial arc plasma deposition. The morphological and structural evolutions of the films driven by laser irradiation (ArF, 193 nm, 20 ns) are examined at different laser energies (0.4–1 J cm−2). Up on laser irradiation, the films revealed hydrogen effusions accompanied by the transformation of sp3 into sp2-hybridization carbon. However, the film irradiated at 0.8 J cm−2 exhibited higher sp3 fractions, which can be attributed to that: a specific value of laser energy density (0.8 J cm−2) can provide a suitable amount of heating that is enough to quench the film and increase the sp3 contents.

DOI： DOI 10.35848/1882-0786/abb871

記述言語：英語   掲載種別：研究論文（学術雑誌）  

We report on the structural evolution of diamond-like carbon (DLC) films by the nanosecond pulsed laser annealing process. DLC film is coated on cemented carbide (WC-Co) by cathodic arc ion plating, which is then annealed by ArF laser (193 nm, 20 ns) at different laser fluences (0.9–1.7 J/cm2). Upon laser annealing, Raman spectra divulge higher sp3 fractions accompanied by a blue shift in the G-peak position, which indicates the changes of sp2 sites from rings to chains. At higher fluence (>1.2 J/cm2), the film converts into reduced graphene oxide confirmed by its Raman-active vibrational modes: D, G, and 2D.

DOI： DOI: https://doi.org/10.1557/mrc.2019.88

記述言語：英語   掲載種別：研究論文（学術雑誌）  

A singlecrystalline diamond (100)(Ib) plate immersed in 2% boric acid was irradiated by 193-nm ArF excimer laser beams for the formation of conductive layers on the surface of an insulating diamond substrate. From current-voltage measurements of the irradiated areas, it was confirmed that semiconducting layers with high conductivities are formed on the diamond surface. It was possible to form ohmic contacts by directly touching tungsten probes with the layer surface. Since Raman spectra exhibited only peaks due to diamond and no peaks due to amorphous carbon, the drastically enhanced conductivity is not attributed to amorphous carbon formation but due to the incorporation of boron atoms into the diamond subsurface from the dopant acid. Secondary ion mass spectrometric depth profile showed the incorporation of boron atoms up to 40 nm depths from the surface. From cathodoluminescence measurements at low temperatures, it was difficult to detect clear peaks for the substitutional incorporation of boron atoms into diamond lattices, which could be attributed to the small thickness of the doped layer for detection. The proposed technique is a new potential method for shallow doping and formation of conductive layers on singlecrystalline diamond surfaces.

DOI： 10.1016/j.diamond.2019.04.013

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Ultrananocrystalline diamond/hydrogenated amorphous carbon composite films were deposited in the ambient of hydrogen by coaxial arc plasma deposition. The film compositions and chemical bonding structures were investigated by X-ray diffraction, X-ray photoemission and hydrogen forward scattering spectroscopies. The sp3/(sp2+sp3) ratio and hydrogen content in the film were estimated to be 64% and 35 at.%, respectively. The optical parameters and the optical dispersion profile were determined by using a variable angle spectroscopic ellipsometer at 55°, 65° and 75° angle of incidence in the photon energy range of 0.9–5 eV. Combinations of multiple Gaussian, and Tauc-Lorentz or Cody-Lorentz dispersion functions are used to reproduce the experimental data. Results of ellipsometry showed a refractive index of approximately 2.05 (at 2eV) and optical band gap of 1.63 eV. The imaginary part of dielectric function exhibited a peak at 3.8 eV, which has assigned to π-π* electron transitions. Furthermore, Electron spin resonance measurements implied the existence of dangling bonds, which might have a partial contribution to the optical absorption properties of the deposited films. A correlation between optical parameters and structural profile of the deposited films is discussed.

DOI： https://doi.org/10.1016/j.cap.2018.11.012

その他リンク： https://www.sciencedirect.com/science/article/pii/S1567173918303171

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Heterojunction diodes comprising poorly (1 at. %) nitrogen-doped n-type ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films and p-type Si substrates were prepared in nitrogen and hydrogen mixed gas atmosphere by coaxial arc plasma deposition. Dark current density–voltage (J–V) characteristics were studied in the temperature range of 200–400 K, in order to investigate the current transport mechanism through the fabricated heterojunctions. The temperature dependence of the ideality factor and reverse saturation current reveals that carrier transport predominantly occurs in the generation–recombination mechanism and, at low temperatures, it accompanies tunneling via weak traps. The heterojunctions surely exhibited photodetection for 254 nm ultraviolet light illumination. It is expected that photocarriers will be generated at UNCD grains and transported through an a-C:H matrix.

DOI： DOI 10.7567/JJAP.56.07KD04

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon (UNCD/a-C:H) films were grown by coaxial arc plasma deposition in the ambient of nitrogen and hydrogen mixed gases. Synthesized films were structurally investigated by X-ray photoemission and near-edge X-ray absorption fine structure spectroscopies. A heterojunction with p-type Si substrate was fabricated to study the ultraviolet photodetection properties of the film. Capacitance–voltage measurements assure the expansion of a depletion region into the film side. Current–voltage curves in the dark showed a good rectifying behaviour in the bias voltages range between ±5 V. Under 254 nm monochromatic light, the heterojunction shows a capability of deep ultraviolet light detection, which can be attribute to the existence of UNCD grains. As the diode was cooled from 300 K down to 150 K, the detectivity has a notable …

DOI： 10.1007/s00339-017-0798-4

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Nitrogen-incorporated ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/aC: H) films were synthesized in nitrogen and hydrogen mixed gas atmospheres by coaxial arc plasma deposition. The temperature dependence of electrical resistivity implies that carriers are transported in hopping conduction. Heterojunctions comprising 3 at.% nitrogen-doped films and p-Si substrates exhibited a typical rectifying action. The expansion of a depletion region into the film side was confirmed from the capacitance–voltage characteristics, and the built-in potential and carrier concentration were estimated to be 0.51 eV and 7.5× 10 16 cm− 3, respectively. It was experimentally demonstrated that nitrogen-doped UNCD/aC: H is applicable as an n-type semiconductor.

DOI： DOI 10.7567/APEX.8.095101

出版者・発行元：Materials Letters  

Heteroepitaxial integration of β-Ga2O3 on diamond (111) has been achieved using radio frequency magnetron sputtering. The β-Ga2O3 epilayer exhibited a high level of in-plane stacking with {-201} parallel to diamond {111}, as confirmed by X-ray diffraction analyses. Pole figure stereographic projections effectively concluded the inoccupancy of (101) texture in the β-Ga2O3 film. The heterojunction preserved its mechanical integration, crystallinity, and heteroepitaxial characteristics up to 900 °C thermal annealing for 40 min. However, annealing at 1000 °C led to structural degradation, attributed to thermal graphitization at the C–O interface. Notably, post-fabrication thermal annealing at 900 °C significantly reduced the oxygen vacancy density in the β-Ga2O3 epilayer from 24.15 % to 15.07 %.

DOI： 10.1016/j.matlet.2025.138753

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出版者・発行元：Journal of Electroanalytical Chemistry  

The electrochemical reduction of carbon dioxide (eCO2RR) has become a very promising pathway that can be used in the transformation of CO2 to important chemical products and, thus, is one of the mitigations of climate change and will contribute toward sustainable chemical production. This review aims at presenting the importance of Nuclear Magnetic Resonance spectroscopy (NMR) to analyze and quantify the liquid-phase products obtained by eCO2RR. This provides a summary regarding the role that NMR plays in the process of reducing carbon dioxide. The following discusses the benefits: identification, complete elucidation, and follow-up on reactions involving CO2 electro-reduction. Pulse experiments corresponding to different methods for water signal suppression are considered separately, outlining some recent developments in the interference water signal reduction which is very crucial for the correct NMR data acquisition in aqueous electrolytes. Certain selected products are described, like carbon monoxide (CO)-associated liquids, formic acid, methanol, and formaldehyde as examples of the NMR precision for the characterization of important compounds. Further, the quantification of C2 products such as ethanol and acetate is discussed in order to illustrate how the technique can be applied in the elucidation of reaction mechanisms and optimization of catalyst performance. This review covers challenges, advanced methodologies, and emerging trends in order to underline the transformative role that NMR plays in advancing CO2 electrochemical reduction toward sustainable chemical synthesis.

DOI： 10.1016/j.jelechem.2025.119097

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi.org/10.1016/j.jelechem.2025.119097

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： doi.org/10.1016/j.jece.2024.114378

掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Environmental Chemical Engineering  

Membrane distillation (MD) has received significant attention because of its energy efficiency and ability to treat industrial wastewater and salty water. However, the synthetic nature of commonly used membranes raises environmental disposal concerns, requiring the development of alternative eco-membranes. To address this issue, a novel, eco-friendly membrane using polylactic acid (PLA) coated with green silica nanoparticles (SiO2 NPs), modified by post-heat treatment, was developed for effective direct contact membrane distillation (DCMD). Herein, two nanofibrous membranes were fabricated via electrospinning/electrospraying: one, PLA, with a 12.5 wt% PLA solution, and another, PLA@SiO2, with 2 % (w/v) SiO2 NPs coating. The PLA@SiO2 membrane demonstrated enhanced hydrophobicity. Various post-heat treatments were applied to optimize membrane properties, such as structure, pore size, hydrophobicity, liquid entry pressure (LEP), thickness, and thermal stability. In addition, the desalination performance of all membranes was evaluated using a DCMD unit for 6 h. Results showed that the heat-pressed then annealed PLA@SiO2 membrane (denoted M44) exhibited notable improvements, including an LEP of 128.7 kPa, a tunable pore size of 0.21 μm, and a contact angle of 135.9°. Furthermore, the M44 membrane demonstrated a porosity of 80.5 %, a stable permeate flux of 14.3 kg.m−2.h−1, and an exceptional salt rejection of 99.99 % over a 24 h DCMD test. This novel eco-membrane shows promising potential for efficient desalination and represents a significant advancement in sustainable MD applications.

DOI： 10.1016/j.jece.2024.114378

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa UK Limited  

DOI： 10.1080/26941112.2024.2418587

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Diamond and Related Materials  

Nanodiamonds were immobilized into chitosan biopolymer to fabricate hybrid microcapsules via electrospraying technique. Previously optimized electrospraying parameters for the formulation of chitosan microcapsules were adjusted to accommodate the immobilized nanodiamonds and maintain a suitable capsule size for the novel hybrid. The yield and entrapment efficiency of the composite microcapsules, including capsule strength were analyzed. The chemical structure, elemental composition, crystalline phases, size distribution, surface morphology, and thermal stability of microcapsules were assessed by Fourier transform infrared (FTIR) spectroscopy, energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), respectively. The results demonstrated a 39 % reduction in the size of composite microcapsules and sphericity improvement after the adjustment. There was a general observation of good yield and immobilization efficiency with the maximum at 96.2 % and 93.8 % for yield and entrapment efficiency, respectively. Characterized composite microcapsules showed desirable morphology, good thermal stability and enhanced mechanical strength, and overall successful fabrication of the hybrid microcapsules. The hybrid microcapsules were subsequently loaded in epoxy resin and coated on a steel substrate to assess their self-healing and anticorrosion abilities. Cross-scratched coating samples were monitored visually for healing efficiency and further analyzed with EIS and potentiodynamic polarization. The self-healing coating showed efficient self-healing and anticorrosion capabilities with a healing efficiency of 97.3 % and a protection efficiency of 99.4 %, confirming the unique feature of the hybrid chitosan-nanodiamonds microparticles for self-healing and anticorrosion purposes.

DOI： 10.1016/j.diamond.2024.111436

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemical Engineering Journal  

Microfluidics is an appealing technique for enhanced oil recovery since it offers numerous advantages over traditional core flooding mechanisms due to their realistic representation of reservoir conditions at the microscale. In this work, we investigated the performance of copper oxide-based nanofluids in the presence of a DCMS-8 cationic surfactant. First, copper oxide nanoparticles of an average particle size of 10 nm were synthesized by the sol–gel method and characterized using various characterization techniques. The results indicated that copper oxide and surfactant-based nanofluids reduced the interfacial tension by 54 %, depending on the concentration of nanoparticles in the suspension. Furthermore, the formation wettability alteration was investigated using contact angle measurements, and the results showed that nanofluid was able to reduce the contact angle from 48o to 20o in 10 min. The shear rheological response indicated that the nanofluids could reduce the viscosity of crude oil from 0.48 (Pa s) to 0.31 (Pa s). Notably, the flooding results showed that copper oxide-based nanofluids were able to recover 61 % of the original oil initially in place, with additional recovery rates of 65 % and 72 % when used with cationic surfactants, polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP), respectively. Finally, the fluorescent images confirmed that surfactant-based nanofluid has a higher sweeping efficiency in porous formation. In this study, the use of copper oxide nanoparticles and cationic surfactant has resulted in the creation of captivating and compelling nanofluids that exhibit reasonable stability of nanoparticles in the base fluid and high recovery rates of residual oil.

DOI： 10.1016/j.cej.2024.151011

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Surface and Interface Analysis  

Among the nondestructive carbon material characterization tools, the prominence of visible Raman spectroscopy has surged remarkably for many years due to its ability to explore a diverse array of carbon bonding configurations. However, to fully unlock the distinctive features concealed within carbon composite materials, additional specimen treatments or precise spectroscope calibrations are necessary. In the same regard, the tiny diamond grain size (5–10 nm) and the pronounced amount of sp2 carbon in the ultrananocrystalline diamond film represent major challenges in visible light excitation. In this work, we employ calibrated oxygen plasma reactive ion etching conditions to manifest the nanodiamond visible Raman signature from ultrananocrystalline diamond/amorphous carbon composite (UNCD/a-C) films fabricated by coaxial arc plasma deposition. Upon plasma etching, the broad defect band in the visible Raman spectra converged toward the diamond characteristic Raman peak at 1332 cm−1. A detailed explanation of band components of the Raman spectra is extracted through peak fitting procedures. The results of Raman spectroscopy are further correlated with the electrical characteristics of the nitrogen-doped UNCD/a-C films due to the optimized oxygen plasma etching processes.

DOI： 10.1002/sia.7289

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemosphere  

Considerable advancements have been made in the development of hydrophobic membranes for membrane distillation (MD). Nonetheless, the environmentally responsible disposal of these membranes poses a critical concern due to their synthetic composition. Herein, an eco-friendly dual-layered biopolymer-based membrane was fabricated for water desalination. The membrane was electrospun from two bio-polymeric layers. The top hydrophobic layer comprises polycaprolactone (PCL) and the bottom hydrophilic layer from cellulose acetate (CA). Additionally, silica nanoparticles (SiO2 NPs) were electrosprayed onto the top layer of the dual-layered PCL/CA membrane to enhance the hydrophobicity. The desalination performance of the modified PCL-SiO2/CA membrane was compared with the unmodified PCL/CA membrane using a direct contact membrane distillation (DCMD) unit. Results revealed that silica remarkably improves membrane hydrophobicity. The modified PCL-SiO2/CA membrane demonstrated a significant increase in water contact angle of 152.4° compared to 119° for the unmodified membrane. In addition, PCL-SiO2/CA membrane has a smaller average pore size of 0.23 ± 0.16 μm and an exceptional liquid entry pressure of water (LEPw), which is 3.8 times higher than that of PCL/CA membrane. Moreover, PCL-SiO2/CA membrane achieved a durable permeate flux of 15.6 kg/m2.h, while PCL/CA membrane showed unstable permeate flux decreasing approximately from 25 to 12 kg/m2.h over the DCMD test time. Furthermore, the modified PCL-SiO2/CA membrane achieved a high salt rejection value of 99.97% compared to a low value of 86.2% for the PCL/CA membrane after 24 h continuous DCMD operation. In conclusion, the proposed modified PCL-SiO2/CA dual-layer biopolymeric-based membrane has considerable potential to be used as an environmentally friendly membrane for the MD process.

DOI： 10.1016/j.chemosphere.2024.141468

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Herein, an eco-friendly dual-layered biopolymer-based membrane was fabricated for water desalination. The membrane was electrospun from two bio-polymeric layers. The top hydrophobic layer comprises polycaprolactone (PCL) and the bottom hydrophilic layer from cellulose acetate (CA). Additionally, silica nanoparticles (SiO2 NPs) were electrosprayed onto the top layer of the dual-layered PCL/CA membrane to enhance the hydrophobicity. The desalination performance of the modified PCL-SiO2/CA membrane was compared with the unmodified PCL/CA membrane using a direct contact membrane distillation (DCMD) unit. Results revealed that silica remarkably improves membrane hydrophobicity. The modified PCL-SiO2/CA membrane demonstrated a significant increase in water contact angle of 152.4° compared to 119° for the unmodified membrane.

DOI： https://doi.org/10.1016/j.chemosphere.2024.141468

その他リンク： https://www.sciencedirect.com/science/article/pii/S0045653524003618

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：International Exchange and Innovation Conference on Engineering and Sciences  

Membrane distillation (MD) is an emerging water purification and desalination technology that offers several advantages over conventional thermal and membrane-based processes. As environmental concerns grow, there is a significant interest in developing eco-friendly membranes for MD applications. This mini-review investigates recent progress in the fabrication of eco-membranes for membrane distillation. Key advancements include using natural polymers like chitosan and cellulose, biodegradable synthetic polymers, and inorganic materials to create more sustainable membrane options. Fabrication techniques such as electrospinning and phase inversion have produced highperformance eco-membranes with enhanced permeability, selectivity, and stability. While challenges remain in scaling up production and optimizing long-term performance, the potential of eco-membranes to significantly reduce MD processes' environmental impact is a promising development that cannot be overlooked. This review provides an overview of eco-membrane materials, fabrication methods, performance characteristics, and future research directions to guide further development in this rapidly evolving field.

DOI： 10.5109/7323379

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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：AIP Conference Proceedings  

Crosslinking of chitosan microcapsules is important for control purposes according to their applications and influences their mechanical, thermal, and chemical stability, and tripolyphosphate (TPP) has been predominantly utilized in the electrospray technique for their production. The properties of chitosan microcapsules produced by electrospraying technique and cross-linked with a mixed cross-linking solution (OxPh), consisting of oxalic acid and sodium phosphate dibasic were studied. The formed capsules were characterized by SEM, XRD, FTIR, and the stability and mechanical properties of the capsules were studied. The cross-linked microcapsules provided smooth morphology and exhibited mechanical strength of 80% in the undried state, with dried state mechanical strength of 21.2N as against 19.8N of TPP cross-linked chitosan microcapsules. The microcapsules were also stable in a pH solution of 3.0-5.0.

DOI： 10.1063/5.0171484

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Physics Express  

In this work, we demonstrate the first achievement in heteroepitaxial growth of β-Ga2O3 thin films on single crystalline diamond (111) wafers using RF magnetron sputtering. A single monoclinic (β-phase) structure with a monofamily { 2 ¯ 01} plane was obtained. XRD pole figure shows ( 2 ̅ 02) and (002) textures of the ( 2 ̅ 01) β-Ga2O3 plane parallel to (111) diamond with six distinct rotational domains, confirming successful epitaxial growth. Collectively, this research provides valuable insights into the epitaxial growth of β-Ga2O3 on diamond via sputtering, paving the way for scalable β-Ga2O3/diamond heterostructures for future electronic and optoelectronic applications with not only high performance but also effective self-thermal management.

DOI： 10.35848/1882-0786/acfd07

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その他リンク： https://iopscience.iop.org/article/10.35848/1882-0786/acfd07/pdf

掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier {BV}  

DOI： 10.1016/j.matpr.2023.09.017

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Physics Express  

We report on negative bias-enhanced growth of quenched-produced diamond films on titanium using hybrid coaxial arc plasma deposition at room temperature. Optimizing the bias voltage to −40 V resulted in a spontaneous formation of a titanium carbide interfacial layer, which caused a significant increase in the adhesion strength from 16 to 48 N. Selective etching of undesired sp 2-C bonded atoms and ultrafast quenching of the energetic carbon ions (C+) promoted the growth of dense sp 3-C bonded atoms, achieving a superhardness of 96 GPa, comparable to natural diamond. These pioneering findings have the potential to revolutionize multifunctional materials for biomedical applications.

DOI： 10.35848/1882-0786/acdfb7

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A hybrid system is proposed to use solar energy as a heating source for the membrane distillation unit. Concentrating photovoltaic needs an efficient cooling system to manage the excess thermal load. Two microchannel heat sinks were proposed to keep the cells from thermal degradation and simultaneously transfer the excess thermal energy to the membrane distillation unit. The results showed a maximum coolant outlet temperature of 59 °C, which is adequate for the membrane distillation unit. A new composite electrospun nanofibrous membrane was successfully synthesized to reduce unfavorable membrane wettability. First, ZIF-L nanoparticles were synthesized and characterized to prove successful preparation, then used as a nanofiller with polystyrene as the polymer membrane matrix for the first time.

DOI： https://doi.org/10.1016/j.jwpe.2023.103872

その他リンク： https://www.sciencedirect.com/science/article/pii/S2214714423003914

掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Water Process Engineering  

A hybrid system is proposed to use solar energy as a heating source for the membrane distillation unit. Concentrating photovoltaic needs an efficient cooling system to manage the excess thermal load. Two microchannel heat sinks were proposed to keep the cells from thermal degradation and simultaneously transfer the excess thermal energy to the membrane distillation unit. The results showed a maximum coolant outlet temperature of 59 °C, which is adequate for the membrane distillation unit. A new composite electrospun nanofibrous membrane was successfully synthesized to reduce unfavorable membrane wettability. First, ZIF-L nanoparticles were synthesized and characterized to prove successful preparation, then used as a nanofiller with polystyrene as the polymer membrane matrix for the first time. SEM, XRD, FTIR, static water contact angle, membrane thickness, and porosity were introduced to prove nanofillers' successful preparation and encapsulation. The antiwetting phenomenon was proven by the measured contact angle of 160°. Furthermore, the fabricated membrane was tested experimentally on a lap scale direct contact membrane distillation unit with a productivity of about 4 kg/m2 h and 18 ppm water quality at 55 °C hot water temperature. Also, the introduced membrane outperformed the productivity of the commercial PVDF membrane at all examined operating conditions.

DOI： 10.1016/j.jwpe.2023.103872

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Express  

In this study, we report on the novel growth of nanodiamond composite (NDC) films on titanium (Ti) substrates using the coaxial arc plasma deposition (CAPD) at room temperature, which offers several advantages over conventional growth techniques. CAPD employs a unique coaxial arc plasma gun structure that provides a supersaturated condition of highly energetic carbon ions (C+) for ultrafast quenching on the substrate, promoting the growth of nanodiamond grains. This allows for NDC films’ growth on diverse substrates without the need for initial seeding or substrate heating. However, the growth of NDC films on Ti substrates at room temperature is challenging due to the native oxide layer (TiO2). Here, we grew NDC films on Ti substrates using three different pretreatments: (i) hydrofluoric acid (HF) etching, (ii) insertion of a titanium carbide (TiC) intermediate layer, and (iii) in situ Ar+ plasma etching. The morphology and structure of the grown NDC films were examined by 3D laser, high-resolution scanning electron microscopies (HR-SEM), Raman, and x-ray photoelectron (XPS) spectroscopies. Our results demonstrate that in situ Ar+ plasma etching is the most effective pretreatment method for completely removing the native TiO2 layer compared to the other two ex situ pretreatments, in which re-oxidation is more likely to occur after these pretreatments. Furthermore, NDC films grown using the hybrid Ar+ ion etching gun (IG) and CAPD exhibit the highest sp 3 content (63%) and adhesion strength (16 N).

DOI： 10.1088/2053-1591/acd992

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The realization of diamond‐based advanced devices is interrelated with the fabrication of practical ohmic contacts. Contrary to boron‐doped, the phosphorus‐doped diamonds with interface carbide forming Ti‐based conventional ohmic contacts find their limitation in device fabrication due to the high contact resistance. Herein, nanocarbon ohmic contacts are deposited by a coaxial arc plasma gun on semiconducting diamonds, and their composite structure which facilitates exceptional contact properties is explored. A comparative electrical characterization between nanocarbon ohmic contacts and conventional Ti‐based contacts is performed on a heavily phosphorus‐doped diamond, and they exhibited one‐order declination in specific contact resistance.

掲載種別：研究論文（学術雑誌）   出版者・発行元：Physica Status Solidi (A) Applications and Materials Science  

The realization of diamond-based advanced devices is interrelated with the fabrication of practical ohmic contacts. Contrary to boron-doped, the phosphorus-doped diamonds with interface carbide forming Ti-based conventional ohmic contacts find their limitation in device fabrication due to the high contact resistance. Herein, nanocarbon ohmic contacts are deposited by a coaxial arc plasma gun on semiconducting diamonds, and their composite structure which facilitates exceptional contact properties is explored. A comparative electrical characterization between nanocarbon ohmic contacts and conventional Ti-based contacts is performed on a heavily phosphorus-doped diamond, and they exhibited one-order declination in specific contact resistance. In addition to the low contact resistance, an ideal ohmic electrode is preferable to have good mechanical adhesion and corrosion resistance for device applications. The contact behavior of n-type diamond/nanocarbon against an extremely corrosive environment realized by boiling H2SO4 + HNO3 solution is analyzed. The nanocarbon ohmic contacts exhibit excellent corrosion resistance and mechanical adhesion over conventional Ti-based contacts. A similar trend is also observed for nanocarbon contacts on boron-doped diamonds. The modest effect on the transfer length of the nanocarbon contacts with respect to acid treatment sessions indicates a tightly bonded diamond/nanocarbon interface and actively suggests their application in highly-corrosive and harsh environments.

DOI： 10.1002/pssa.202200627

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/pssa.202200627

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：International Exchange and Innovation Conference on Engineering and Sciences  

Color centers in diamonds have promising and unique properties that can be optimized and engineered for several quantum-sensing applications. The negatively charged Nitrogen-vacancy (NV) center is one of the outstanding candidates due to its stable luminescence and spin features. It has a long coherence time that can be initialized and manipulated with high accuracy at room temperature. Nonetheless, many parameters, namely; nonradiative centers, complex defects, and nitrogen-based defect centers can severely affect the desirable properties of these NV centers. In this review, we highlight the recent advances of color center fabrication, parameters optimization, and current challenges to enhance these properties, with main focus on magnetometry applications.

DOI： 10.5109/7158033

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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：International Exchange and Innovation Conference on Engineering and Sciences  

Nanodiamond composite coatings combine diamond crystallites embedded inside an amorphous carbon phase. Owing to sp3 hybridized carbon bonding of diamond crystallites, these films yield impressive mechanical properties, outstanding biocompatibility, and antibacterial properties. Commonly, Nanodiamond films are prepared by chemical vapor deposition (CVD). In CVD, the initial nucleation of diamond is required, specifically, a seeding procedure with diamond powders as a pretreatment of substrates prior to the film deposition, and high substrate temperature. Such preparation conditions limit the variety of non-diamond substrates used for the heterogeneous growth of diamond films by CVD. On the other hand, Quenched-produced diamonds, formerly called Nanodiamond (ND) films have been grown by a physical vapor deposition approach, namely coaxial arc plasma deposition (CAPD), without the pretreatment of substrates and at room temperature. In our research group at Kyushu University, we realized the growth of Quenched-produced diamond films by the CAPD method. For electronic applications, we demonstrated the n-and p-type semiconductors by Nitrogen and Boron doping, respectively [1-3]. Most recently, we succeeded in the growth of Q-diamond on Titanium substrates at room temperature by a hybrid configuration of ion etching gun (IG) and CAPD employing in-situ Argon etching. The grown Q-diamond on Ti has been proposed for the implant applications [4,5]

DOI： 10.5109/7157924

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials  

Chitosan microcapsules draw attention due to their biodegradability, biocompatibility, antibacterial behavior, low cost, easy processing, and the capability to be used for different applications. This study utilized the electrospraying technique for the chitosan microcapsules formulation. As a novel cross-linking agent, a mixture of oxalic acid and sodium phosphate dibasic was utilized as a collecting solution for the first time in the electrospraying of chitosan microcapsules. Scanning Electron Microscopy (SEM) was utilized to optimize the spherical morphology and size of the experimentally obtained microcapsules. The different parameters, including chitosan concentration, applied voltage, flow rate, and tip-to-collector (TTC) distance, affecting the microcapsules’ size, sphericity, yield, and combined effects were optimized using Surface Responses Methodology (RSM). The Analysis of Variance (ANOVA) was utilized to obtain the impact of each parameter on the process responses. Accordingly, the results illustrated the significant impact of the voltage parameter, with the highest F-values and least p-values, on the capsule size, sphericity, and yield. The predicted optimum conditions were determined as 5 wt% chitosan concentration, 7 mL/h flow rate, 22 kV, and 8 cm TTC distance. The predicted responses at the optimized conditions are 389 µm, 0.72, and 80.6% for the capsule size, sphericity, and yield, respectively. While the validation of the model prediction was conducted experimentally, the obtained results were 369.2 ± 23.5 µm, 0.75 ± 0.04, and 87.3 ± 11.4%, respectively. The optimization process was successfully examined for the chitosan microcapsules manufacturing.

DOI： 10.3390/ma15238447

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Express  

Diamond-based Schottky barrier diodes (SBDs) are involved in many technological applications. In a conventional SBD fabrication process that involves interface carbide forming ohmic contacts, a post-annealing step is necessary for ohmic contacts to achieve their operational efficiency. However, this step deteriorates the essential oxygen coverage at the diamond surface which in turn affects SBDs uniformity. So, an additional oxygen termination step is necessary prior to Schottky metal deposition. In this study, a non-conventional fabrication method is introduced using corrosion-resistant nanocarbon ohmic contacts fabricated by coaxial arc plasma deposition. As a result, The SBD parameters including ideality factors and barrier heights exhibited high uniformity with a very small standard deviation for the proposed fabrication process flow when compared with process flow including a post-annealing step. Furthermore, the contact behavior of nanocarbon ohmic electrodes is investigated on a heavily boron-doped diamond film using circular transmission line model theory and a specific contact resistance of ∼10−5 Ωcm2 is obtained, suggesting the practical application of nanocarbon ohmic contacts for diamond-based electronic devices.

DOI： 10.1088/2053-1591/aca31f

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Physics Express  

It has been extremely difficult for nanodiamond composite (NDC) films to be deposited on Ti due to a large thermal expansion coefficient difference. The native oxide layer on Ti is another problem preventing the appropriate adhesion of NDC films and subsequent delamination. In this work, innovative room temperature adhesion of 3 μm NDC films with 54 GPa hardness on Ti substrates was accomplished via a hybrid system of ion etching gun and coaxial arc plasma deposition (CAPD). Ar+ plasma etching is capable to terminate the superficial TiO2 layer and manipulates substrate morphology during CAPD provides instantaneous deposition of NDC films at room temperature.

DOI： 10.35848/1882-0786/ac99b6

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掲載種別：研究論文（学術雑誌）   出版者・発行元：AIP Advances  

n-Type (phosphorus-doped) diamond is a promising material for diamond-based electronic devices. However, realizing good ohmic contacts for phosphorus-doped diamonds limits their applications. Thus, the search for non-conventional ohmic contacts has become a hot topic for many researchers. In this work, nanocarbon ohmic electrodes with enhanced carrier collection efficiency were deposited by coaxial arc plasma deposition. The fabricated nanocarbon ohmic electrodes were extensively examined in terms of specific contact resistance and corrosion resistance. The circular transmission line model theory was used to estimate the charge collection efficiency of the nanocarbon ohmic electrodes in terms of specific contact resistance at a specific voltage range (5-10 V); they exhibited a specific contact resistance of 1 × 10-3 ωcm2. The result revealed one order reduction in the specific contact resistance and, consequently, a potential drop at the diamond/electrode interface compared to the conventional Ti electrodes. Moreover, the fabricated nanocarbon electrodes exhibited high mechanical adhesion and chemical inertness over repeated acid treatments. In device applications, the nanocarbon electrodes were evaluated for Ni/n-type diamond Schottky diodes, and they exhibited nearly one order enhancement in the rectification ratio and a fast charge collection at lower biasing voltages.

DOI： 10.1063/5.0093470

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

n-Type (phosphorus-doped) diamond is a promising material for diamond-based electronic devices. However, realizing good ohmic contacts for phosphorus-doped diamonds limits their applications. Thus, the search for non-conventional ohmic contacts has become a hot topic for many researchers. In this work, nanocarbon ohmic electrodes with enhanced carrier collection efficiency were deposited by coaxial arc plasma deposition. The fabricated nanocarbon ohmic electrodes were extensively examined in terms of specific contact resistance and corrosion resistance. The circular transmission line model theory was used to estimate the charge collection efficiency of the nanocarbon ohmic electrodes in terms of specific contact resistance at a specific voltage range (5–10 V); they exhibited a specific contact resistance of 1× 10− 3 Ωcm 2.

DOI： https://doi.org/10.1063/5.0093470

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In this study, we report on the complex formation and characterization of nano-bio conjugates synthesized by the sol–gel chemical method. The nano-bio conjugates, consisting of inorganic ZnO nanoparticles (NPs) and organic nitrogenous bases of DNA (Thymine and Cytosine), are investigated using electron microscopies, molecular vibrational analysis and X-ray spectroscopies. In this experimental investigation, we used two basic nitrogenous bases of DNA – Cytosine, and Thymine. The X-ray diffraction patterns of both ZnO NP and the nanoconjugate (NJ) reveal a highly phase pure ZnO structure with negligible changes in the unit cell dimensions. The Raman peaks due to the molecular vibration of C2=O7 and C4=O8 sites of Thymine and C=O and N-H sites in Cytosine are shifted due to the cation affinity after the interaction with ZnO NPs.

その他リンク： https://www.sciencedirect.com/science/article/pii/S2352507X2200035X

掲載種別：研究論文（学術雑誌）   出版者・発行元：Nano-Structures and Nano-Objects  

In this study, we report on the complex formation and characterization of nano-bio conjugates synthesized by the sol–gel chemical method. The nano-bio conjugates, consisting of inorganic ZnO nanoparticles (NPs) and organic nitrogenous bases of DNA (Thymine and Cytosine), are investigated using electron microscopies, molecular vibrational analysis and X-ray spectroscopies. In this experimental investigation, we used two basic nitrogenous bases of DNA – Cytosine, and Thymine. The X-ray diffraction patterns of both ZnO NP and the nanoconjugate (NJ) reveal a highly phase pure ZnO structure with negligible changes in the unit cell dimensions. The Raman peaks due to the molecular vibration of C2=O7 and C4=O8 sites of Thymine and C=O and N-H sites in Cytosine are shifted due to the cation affinity after the interaction with ZnO NPs. The shifted XPS spectra towards higher binding energies of the NJ divulge the atomic level interaction between the DNA bases and ZnO NPs at the surface. Moreover, the formation of NJs reduces the surface defect states of the ZnO NPs and increases the fluorescence properties by quenching the oxygen vacancy concentration. Thus, the current study on the interfacial properties of organic–inorganic conjugate materials opens new frontiers for developing novel nano-bio conjugate materials and their integration for targeted drug delivery, biomolecular sensing and therapeutic tools medicine applications.

DOI： 10.1016/j.nanoso.2022.100898

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掲載種別：研究論文（学術雑誌）   出版者・発行元：C-Journal of Carbon Research  

Carbon-based materials (CBMs) such as graphene, carbon nanotubes (CNT), highly ordered pyrolytic graphite (HOPG), and pyrolytic carbon (PyC) have received a great deal of attention in recent years due to their unique electronic, optical, thermal, and mechanical properties. CBMs have been grown using a variety of processes, including mechanical exfoliation, pulsed laser deposition (PLD), and chemical vapor deposition (CVD). Mechanical exfoliation creates materials that are irregularly formed and tiny in size. On the other hand, the practicality of the PLD approach for large-area high-quality CMB deposition is quite difficult. Thus, CVD is considered as the most effective method for growing CBMs. In this paper, a novel pulsed laser-assisted chemical vapor deposition (LCVD) technique was explored to determine ways to reduce the energy requirements to produce high quality CBMs. Different growth parameters, such as gas flow rate, temperature, laser energy, and deposition time were considered and studied thoroughly to analyze the growth pattern. CBMs are grown on Si and Cu substrates, where we find better quality CBM films on Cu as it aids the surface solubility of carbon. Raman spectroscopy confirms the presence of high-quality PyC which is grown at a temperature of 750 °C, CH4 gas flow rate of 20 sccm, a laser frequency of 10 Hz, and an energy density of 0.116 J/cm2 per pulse. It is found that the local pulsed-laser bombardment helps in breaking the carbon-hydrogen bonds of CH4 at a much lower substrate temperature than its thermal decomposition temperature. There is no significant change in the 2D peak intensity in the Raman spectrum with the further increase in temperature which is the indicator of the number of the graphene layer. The intertwined graphene flakes of the PyC are observed due to the surface roughness, which is responsible for the quenching in the Raman 2D signal. These results will provide the platform to fabricate a large area single layer of graphene, including the other 2D materials, on different substrates using the LCVD technique.

DOI： 10.3390/c8020024

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Physica B: Condensed Matter  

Composite films of polyvinyl alcohol/lead iodide (PVA/PbI2) were prepared with different concentrations of PbI2 using low-cost casting process. The characteristics of the prepared films were analyzed by XRD and SEM. The XRD results showed increased crystalline nature with PbI2 content and the SEM micrographs revealed homogeneous particles distribution of PbI2 within the polymer. The optical parameters of PVA/PbI2 films were measured through UV–Vis absorption-transmittance spectroscopy. The indirect energy gap for PVA was found to be 4.75 eV, while the PVA/PbI2 film with 10 wt% PbI2 showed direct transition of 2.47 eV and indirect transition of 2.15 eV. The PVA film resistivity was found to be 1.79 × 109 Ω cm in the dark and decreased to1.85 × 108 Ω cm at 7000 lux. The film resistivity was found to decrease as the PbI2 content ratio increased up to 10 wt%. The results also showed gradual increase in photo sensitivity with increasing PbI2 content ratio in the composite films. The optical properties revealed that the composite films (PVA/PbI2) could be used in different optoelectronic applications.

DOI： 10.1016/j.physb.2021.413604

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1016/j.physb.2021.413604

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Science in Semiconductor Processing  

In this study, we employed an authentic process for the device fabrication of diamond detectors, wherein thin, highly conductive surface layers were processed in bulk diamond substrate using a nanosecond-pulsed excimer laser with liquid-immersion irradiation. The incorporation of high-concentration phosphorus dopants at 40 nm under the irradiated surface characterized the irradiated areas with much lower electrical resistivity, which was adequate for demonstrating ohmic contacts even with the tungsten probe heads at room temperature. In particular, a low activation energy (<54 meV) of irradiated surfaces enabled space-charge-free build-up effects between the diamond film and external connection. Moreover, the electrical characterization revealed an improved carrier-collection efficiency that was more than three orders of magnitude greater than that of typical Ti/Au diamond ohmic contacts, including a high-response speed of the current pulse to irradiation burst. The laser treatment of diamond films displayed promising results for the fabrication of diamond detectors with minimum power consumption, fastest process rate, and highest visible-light detection that could maintain smooth and stable charge transport. The process allowed selective, patterned doping of the diamond surface, which could be electrically contacted more readily. Furthermore, they could be operated at high temperatures and in radiation-harsh environments with sustainable efficiency.

DOI： 10.1016/j.mssp.2021.106370

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.3390/nano12050854

掲載種別：研究論文（学術雑誌）   出版者・発行元：Nanomaterials  

Diamond is one of the fascinating films appropriate for optoelectronic applications due to its wide bandgap (5.45 eV), high thermal conductivity (3320 W m−1·K−1 ), and strong chemical stability. In this report, we synthesized a type of diamond film called nanocrystalline diamond (NCD) by employing a physical vapor deposition method. The synthesis process was performed in different ratios of nitrogen and hydrogen mixed gas atmospheres to form nitrogen-doped (n-type) NCD films. A high-resolution scanning electron microscope confirmed the nature of the deposited films to contain diamond nanograins embedded into the amorphous carbon matrix. Sensitive spectroscopic investigations, including X-ray photoemission (XPS) and near-edge X-ray absorption fine structure (NEXAFS), were performed using a synchrotron beam. XPS spectra indicated that the nitrogen content in the film increased with the inflow ratio of nitrogen and hydrogen gas (IN/H ). NEXAFS spectra revealed that the σ*C–C peak weakened, accompanied by a π*C=N peak strengthened with nitrogen doping. This structural modification after nitrogen doping was found to generate unpaired electrons with the formation of C–N and C=N bonding in grain boundaries (GBs). The measured electrical conductivity increased with nitrogen content, which confirms the suggestion of structural investigations that nitrogen-doping generated free electrons at the GBs of the NCD films.

DOI： 10.3390/nano12050854

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.3390/polym14040709

掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymers  

Owing to bio-polymer’s low-cost, environmental friendliness and mechanically stable nature, calcium alginate microcapsules have attracted much interest for their applications in numerous fields. Among the common production methods, the Electrospraying technique has shown a great potential due to smaller shape capsule production and ease of control of independent affecting parameters. Although one factor at a time (OFAT) can predict the trends of parameter effect on size and sphericity, it is inefficient in explaining the complex parameter interaction of the electrospray process. In the current study, the effects of the main parameters affecting on size and sphericity of the microcapsules using OFAT were optimized to attain calcium alginate microcapsules with an average diameter below 100 µm. Furthermore, we propose a statistical model employing the Surface Responses Methodology (RSM) and Central Composite Design (CDD) to generate a quadratic order linear regression model for the microcapsule diameter and sphericity coefficient. Experimentally, microcapsules with a size of 92.586 µm and sphericity coefficient of 0.771 were predicted and obtained from an alginate concentration of 2.013 w/v, with a flowrate of 0.560 mL/h, a needle size of 27 G and a 2.024 w/v calcium chloride concentration as optimum parameters. The optimization processes were successfully aligned towards formation of the spherical microcapsules with smaller average diameter of less than 100 µm, owing to the applied high voltage that reached up to 21 kV.

DOI： 10.3390/polym14040709

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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：Materials Research Letters  

We report the fabrication of p-n + diamond homojunction through an innovative approach of laser irradiation in liquid-ambient. A shallow phosphorus-doped layer with a high electric conductivity is processed on top of a p-type diamond substrate to form the p-n + homojunction. The current–voltage measurements at room temperature confirmed high conductivity of the induced n+ layer and showed exceptional rectification properties with an ideality factor of 1.07, excellent low on-resistance of 3.7 × 10−2 Ωcm2, and current density over 260 Acm−2 at forward-biasing of 10 V. Furthermore, undetectable leakage-current provides a rectification ratio exceeding 1010 at ±6 V, promoting the junction in UV detection applications.

DOI： 10.1080/21663831.2022.2083457

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Engineering Materials  

Supercapacitors, known as electrochemical capacitors, are very attractive as energy storage devices due to their high-power density (up to 410 kW kg⁻¹), their unique ability to undergo charge/discharge quickly and their long cycling life (that could reach 4105 cycles). Efforts have been dedicated to develop various carbon-based nanomaterials for energy storage, specially supercapacitors. Carbon-based materials and conducting polymers (ie; Polypyrrole and Polyaniline) are considered the most promising candidates for capacitive materials, as they offer high charging capacity through diverse mechanisms. Among these carbon-based materials are nano-crystalline diamond (NCD) films, which were widely studied during the past decades due to their special features like; short-range sp³ bonded carbon atoms and large surface to volume ratio. Artificial fabrication of NCD films was developed using various techniques like; high-pressure high-temperature (HPHT), chemical vapor deposition, plasma-discharge-stimulated, laser ablation,hot-filament technique,, and coaxial arc plasma deposition. Although carbon-based nanomaterials display good stability in energy storage applications, the capacitance values are yet limited by the microstructures within the materials; Therefore, their nanocomposites with conducting polymers provide higher performance and improved properties. This chapter aims to summarize and discuss the recent synthetic developments of nanocrystalline diamond/conducting polymer nanocomposites, and their applications to energy storage and supercapacitor.

DOI： 10.1007/978-3-030-94319-6_32

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Science Forum  

There has been a surge in applying alginate microcapsules in diverse fields due to the numerous advantages of their non-toxicity, simple synthesis, and mechanical and chemical stability. Electrospraying is a simple and excellent technique for producing small microcapsules. This study aimed to analyze the trends in the operational parameters of the electrospraying technique, observed extreme conditions of the electrospraying, and selected the best performing parameters for producing small and spherical microcapsules. Alginate concentration was found to produce smaller microcapsules when kept at a minimum. However, the Implosion of microcapsules formed with less than 2%w/v alginate concentration was observed. Voltage increment produced smaller capsules, and fibre formation began at 21kV. Lower feed rates favoured both smaller microcapsules and better sphericity. Reduction in the needle orifice also favoured the formation of smaller microcapsules with less sphericity. Overall, a needle gauge of 27G, a voltage of 21kV, a flowrate of 0.5ml/h, and 2% w/v calcium chloride concentration were the best parameter combinations for producing small and spherical microcapsules.

DOI： 10.4028/p-hkud3w

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： DOI: 10.1109/ACCESS.2020.3046969

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1016/j.tsf.2020.138222

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： https://doi.org/10.1016/j.mssp.2018.06.028

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Nitrogen-doped ultra-nanocrystalline diamond/hydrogenated amorphous carbon composite films prepared in hydrogen and nitrogen mixed-gas atmospheres by coaxial arc plasma deposition with graphite targets were studied electrically and chemical-bonding-structurally. The electrical conductivity was increased by nitrogen doping, accompanied by the production of n-type conduction. From X-ray photoemission, near-edge X-ray absorption fine-structure, hydrogen forward-scattering, and Fourier transform infrared spectral results, it is expected that hydrogen atoms that terminate diamond grain boundaries will be partially replaced by nitrogen atoms and, consequently, π C–N and C= N bonds that easily generate free electrons will be formed at grain boundaries.

DOI： 10.7567/APEX.10.015801

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were deposited on P-type Si substrates by coaxial arc plasma deposition. The deposited films possessed N-type conduction, and evidently formed pn heterojunctions with P-type Si substrates. The heterojunction devices showed typical rectification properties similar to those observed for conventional abrupt pn heterojunctions. The conduction mechanisms that govern current transport in these devices were analyzed using dark current–voltage measurements in the temperature range from 300 K to 80 K. The results revealed that a trap-assisted multi-step tunneling process is a dominant mechanism at lower temperatures and low forward bias. At least two defect levels with activation energies of 42 and 24 meV appear to activate this process. At moderate forward bias, the current followed a power-law …

DOI： 10.1166/jnn.2016.13663

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： DOI 10.7567/JJAP.55.07LE01

その他リンク： https://iopscience.iop.org/article/10.7567/JJAP.55.07LE01/meta

開催年月日： 2023年7月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Seville, Spain   国名：スペイン  

開催年月日： 2021年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：GIS TAIPEI TECH Convention Center   国名：台湾  

開催年月日： 2018年11月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Hynes Convention Center, Boston   国名：アメリカ合衆国  

その他リンク： https://www.mrs.org/meetings-events/fall-meetings-exhibits

開催年月日： 2023年10月

記述言語：英語   会議種別：口頭発表（基調）  

開催地：C-Cube Hall, Faculty of Engineering Sciences, Kyushu University   国名：日本国  

開催年月日： 2023年7月

記述言語：英語  

開催地：Sophia University, Tokyo   国名：日本国