A5101485403- Electronic and Structural Properties of Oxides
- Advanced Photocatalysis Techniques
- Luminescence Properties of Advanced Materials
- Catalytic Processes in Materials Science
- Inorganic Chemistry and Materials
- MXene and MAX Phase Materials
- Ferroelectric and Piezoelectric Materials
- Bone Tissue Engineering Materials
- Semiconductor materials and devices
- Calcium Carbonate Crystallization and Inhibition
- Microwave Dielectric Ceramics Synthesis
- Copper-based nanomaterials and applications
- Advanced ceramic materials synthesis
- ZnO doping and properties
- Analytical Chemistry and Sensors
- Ammonia Synthesis and Nitrogen Reduction
- Gas Sensing Nanomaterials and Sensors
- Quantum Dots Synthesis And Properties
- Advanced Fiber Optic Sensors
- Mercury impact and mitigation studies
- Physics of Superconductivity and Magnetism
- Nuclear materials and radiation effects
- Magnetic and transport properties of perovskites and related materials
- Glass properties and applications
- Perovskite Materials and Applications
Tokyo Institute of Technology
2006-2024
Meiji University
2015-2024
International University of Japan
2010-2022
National Institute of Information and Communications Technology
2021
Shinshu University
2021
Nagano Municipal Hospital
2021
Shizuoka University
2008-2020
Tohoku University
2018-2020
Nagoya Institute of Technology
2020
Ehime University
2020
Local structures in ceria-based materials were investigated by UV resonance Raman spectroscopy using a 363.8 nm laser line for the first time. In spectra of highly crystalline and undoped ceria, overtone LO series are clearly detected due to multiphonon relaxation effect. Gd3+ doping ceria additionally activates disorder bands that attributable lattice spaces with or without an oxygen vacancy. The crystal size dependency suggests Ce3+ ions preferably form MO8-type (M = Ce3+) complex...
A multinary nitride, Eu-doped CaAlSiN3, which had previously been synthesized at 1600–1800 °C as a red-emiting phosphor material, was obtained 500–800 via the reaction of CaAlSi alloy with low concentration Eu (composition Ca0.992Eu0.008AlSi) in ammonia present study. In supercritical (100 MPa), CaAlSiN3 formed temperatures ≥ 500 both and without addition sodium amide. The amide significantly facilitated synthesis prevented presence unreacted silicon, could be due to formation...
Abstract Among binary compounds, there is a high potential for discovery of novel members (polymorphic phases or compounds) the nitrides transition metals group due to pronounced dependence oxidation state (M) on pressure. The power pressure–high temperature (HP‐HT) route synthesis has already been demonstrated by cubic 4 and 14 elements, crystalline polymorphs P 3 N 5 , reports formation four noble metal nitrides. It anticipated that such HP products exhibit, in addition enhanced elastic...
A solution route toward multinary nitrides was demonstrated in the synthesis of Eu-doped CaAlSiN3. During a metal−ammonometallate−nitride conversion ammonia system, nitride crystallized into red-emitting nanocrystals at temperatures up to only 800 °C, i.e., 1000 °C lower than previous method.
Perovskite-type oxynitride SrTaO 2 N is of significant interest because its photocatalytic activity and dielectric property. was previously investigated in the forms powder, sintered bodies, thin films. In...
This paper presents an aqueous route to size-controlled and doped CeO2 nanoparticles using the Ce-oleate complex as a chemically modified precursor. In this synthesis, hydrolytic condensation of by ammonia solution at room temperature leads 2.2 nm sized nanocrystals. These products are dispersible in nonpolar solvents owing hydrophobic nature surface oleate ligand. Moreover, size nanocrystals is controllable up 5.2 subsequent hydrothermal treatment 200 °C. The proposed method can be extended...
In this report, we describe a novel solvothermal procedure for the synthesis of nanosized particles barium titanate (BaTiO3). We have been able to synthesize large amounts nearly uniform sized BaTiO3 nanocrystals in size range 5−37 nm. The advantages our technique over other previously reported hydrothermal/solvothermal approaches are high yield and simple but precise control particles, which is very conveniently achieved by changing water content reaction mixture measured way....
Seed nanocrystals formed by the coprecipitation of ferric and ferrous ions with oleate modification, at molar ratios sodium Fe ion [SO]/[Fe] from 0.05 to 0.5, were subjected a hydrothermal treatment 100−230 °C initiate crystal growth. Fourier transform infrared spectroscopy revealed that these stabilized surface stable colloidal solution in various nonpolar solvents such as cyclohexane benzene. An X-ray diffraction analysis showed higher temperatures lower concentration promoted Ostwald...
Crystalline sodium tantalate thin films with pyrochlore (Na2Ta2O6) and perovskite (NaTaO3) structures are successfully synthesized on Ta metal substrates by a hydrothermal−electrochemical method at low temperature (≤473 K). The phase, film thickness, domain size of the shown to be controllable appropriate adjustment reaction conditions. Film formation mechanisms for both Na2Ta2O6 NaTaO3 proposed based experimental results.
Abstract A fine powder of sodium tantalum(V) trioxide as single-phase perovskite NaTaO3 has been successfully prepared by hydrothermal synthesis through the reaction a hydroxide solution and ditantalum pentaoxide at low temperature (373–473 K). The high photocatalytic activity for both H2 evolution (8.0 mmol h−1) O2 (4.1 h−1), which is attributed to surface area, small particle size crystallinity catalyst.
Abstract The photocatalytic activity of tantalum nitride (Ta3N5) for H2 evolution under visible-light irradiation (λ > 420 nm) is improved fivefold by 10 MPa ammonia treatment at 823 K. rate the treated samples highly related to time and temperature.
The photocatalytic activity of beta-Ge(3)N(4) powder for overall water splitting is successfully enhanced by ammonia treatment at 823 K 5-24 h pressures 20 MPa or greater. surface and bulk nitrogen content in the treated samples varies according to temperature time, related stability under pressurized ammonia. change resulted a splitting. A 5 exhibited 4 times higher than that as-synthesized powder, attributable decrease density anion defects surface.
We have successfully employed an oleate-modified nucleation/hydrothermal growth process for the synthesis of YVO4:Eu3+ nanoparticles. Oleate-passivated nanoparticles, formed by precipitation Y/Eu-oleate complex Na3VO4 solution, were subjected to hydrothermal treatment at 200 °C 6 h initiate crystal growth. The resultant nanoparticles (average grain size 16.1 nm) show well-defined red luminescence due radiative transitions from 5D0 7FJ (J: 1−4) levels Eu3+. Significantly, disperse well in...
Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report development room nanosized Co-doped barium titanate particles with a size around 14 nm, synthesized by solvothermal drying method. A combination x-ray diffraction state-of-the-art electron microscopy techniques confirms intrinsic doping Co into BaTiO3. The was tracked down to different donor defects, namely hydroxyl groups at oxygen site () and vacancies (), their...
Because of its use as a mother crystal red phosphor in white LEDs, SrAlSiN3 is very interesting complex nitride. Till date, the only examples europium-doped synthesis have been high-pressure nitrogen atmospheres at high temperatures above 2000 K 190 MPa with typical solid-state reaction. In comparison, our research first to achieve such an extremely low temperature 773 100 MPa. addition, we document instance using supercritical ammonia fluid NaNH2 reaction medium. Moreover, knowledge, this...
The formation of tetragonal Zr(0.5)Ce(0.5)O(2) solid solution nanocrystallites 5 +/- 1 nm size by a hydrothermal method at 120 degrees C for 6 h was confirmed careful Raman and XRD studies the first time. It characterized as t' '-form with an axial ratio c/a = but oxygen ion displacements. as-prepared sample hydrous in nature, which is responsible lattice expansion. However, most water held structure can be expelled heating above 600 C. Above 1050 50 dissociates into two phases, cubic phase...
We report the effects of synthesis pressure and sodium content in reactants on lattice structure photoluminescence properties Eu‐doped CaAlSiN 3 , a red phosphor, synthesized by low‐temperature process (up to 800°C) from ammonometallates. The parameters average anisotropic values crystallite size strains were calculated refining against X‐ray diffraction data. These are correlated with content. light emission was shown be result compromise between cell dimensions strains. sample obtained at...