A5002178790- Luminescence Properties of Advanced Materials
- Inorganic Chemistry and Materials
- Radiation Detection and Scintillator Technologies
- Perovskite Materials and Applications
- MXene and MAX Phase Materials
- Solid-state spectroscopy and crystallography
- Luminescence and Fluorescent Materials
- X-ray Diffraction in Crystallography
- Ammonia Synthesis and Nitrogen Reduction
- Rare-earth and actinide compounds
- Boron and Carbon Nanomaterials Research
- Advanced Photocatalysis Techniques
- Nuclear materials and radiation effects
- Crystallization and Solubility Studies
- Physics of Superconductivity and Magnetism
- Crystal Structures and Properties
- Gas Sensing Nanomaterials and Sensors
- Advanced Condensed Matter Physics
- Advanced ceramic materials synthesis
- Chemical Synthesis and Characterization
- Inorganic Fluorides and Related Compounds
- Acoustic Wave Resonator Technologies
- Ferroelectric and Piezoelectric Materials
- Machine Learning in Materials Science
- Zeolite Catalysis and Synthesis
National Institute for Materials Science
2015-2025
University of Tsukuba
2021
Material (Belgium)
2014
Nagoya Institute of Technology
2008-2010
Japan Atomic Energy Agency
1999
Tohoku University
1995
Discovery of novel luminescent materials is fundamental importance in the advancement solid state lighting and flat panel display technologies. In this work, we report a single-particle-diagnosis method for discovery new phosphors by just characterizing crystalline particle as small 10 μm diameter. We explored single-particle fluorescence imaging spectroscopy techniques to evaluate photoluminescence phosphor distinguished from complex powder mixture applied high-resolution single-crystal...
Upon UV or blue light excitation, the codoped γ-AlON phosphor has higher luminescence intensity, quantum efficiency and thermal stability than Mn<sup>2+</sup>-doped due to energy transfer low total concentration of Ce<sup>3+</sup> Mn<sup>2+</sup> ions.
The single-particle-diagnosis approach allows for the fast discovery of novel luminescent materials using powdered samples. This paper reports a new blue-emitting Sr3Si8–xAlxO7+xN8–x:Eu2+ phosphor solid state lighting and its scale-up synthesis. structure-, composition-, temperature-dependent luminescence were investigated discussed by means various analytic techniques including single-crystal XRD diffractometer, single-particle fluorescence spectroscopy, FTIR spectra, decay time,...
Discovery of new phosphors with desired properties is great significance for developing high optical quality solid-state lighting. The single-particle-diagnosis approach an effective way to search novel by analyzing tiny single crystals screened from the fired powder mixtures. In this work, a broadband orange-emitting phosphor Sr<sub>3</sub>Si<sub>8</sub>O<sub>4</sub>N<sub>10</sub>:Eu<sup>2+</sup> solid state lighting was discovered method. oxonitridosilicate crystallizes in monoclinic space...
A novel orange-yellow-emitting Ca<sub>1.62</sub>Eu<sub>0.38</sub>Si<sub>5</sub>O<sub>3</sub>N<sub>6</sub>phosphor was discovered by a single-particle-diagnosis approach for UV, or blue LED driven white-LEDs.
Eu3+-doped YSiO2N phosphor was synthesized, and its crystal structure analyzed by single-crystal X-ray neutron powder diffraction techniques. The new of with the monoclinic lattice (space group C2/c) composed nonequivalent [YO6N2] dodecahedra identified, and, in this structure, five different Y3+ sites take Ci or Cn symmetry. Based on experimentally determined we characterized luminescence properties Eu3+ ions site-selective time-resolved spectroscopy. at Y: show intense 5D0 → 7F2 electric...
Single crystal particles of Na 2 BaZr[SiO 4 ] [systematic name: disodium barium zirconium bis(orthosilicate)] and BaHf[SiO [disodium hafnium were extracted from grain-grown polycrystals obtained by heating compacts binary oxide mixtures at 1473 K. X-ray diffraction analysis revealed that these are isostructural orthosilicates with a glaserite-type structure, in which all sites X , Y M T the general formula XY [ ( O ) fully occupied atoms different elements. The structures title compounds...
Novel Sr2–yEuyB2–2xSi2+3xAl2–xN8+x phosphors were investigated as a function of the boron and aluminum over silicon ratio Eu2+ concentration. Samples prepared via solid-state reaction synthesis by carefully controlling conditions composition. At high content, that is, x = 0, 5d–4f emission is observed which maximum shifts from 595 nm for low Eu concentrations (y 0.005) toward 623 0.5). The samples can be excited UV or blue light up to ∼475 nm. Substitution [B2Al]9+ units [Si3N]9+ units,...
A new sialon Eu3.60LiSi13.78Al6.03O6.82N22.59 has been discovered via the single-particle diagnosis approach. Its crystal structure (space group P3m1) was solved and refined from single-crystal X-ray diffraction data. It interesting feature of two types disorder at Eu2 site: positional (Eu2a/Eu2b) substitutional with (Si/Al)2(O/N). The is generalized to formula A4–mBnC19+2mX29+m (A = Sr, La, Eu, Ce; B Li; C Si, Al; X O, N; 0 ≤ m 1; n 1), which Sr3.61LiSi14.27Al5.61O6.19N23.25 (Sr–sialon,...
The crystal structure of Al 7 O 3 N 5 was characterized by laboratory X-ray powder diffraction (Cu Kα 1 ). title compound is trigonal with a space group R m (centrosymmetric). hexagonal unit-cell dimensions ( Z = 3) are 0.305 06(1) nm, c 5.7216(1) and V 0.461 11(2) nm . initial structural model derived the charge-flipping method refined Rietveld method. final showed positional disordering two four sites. maximum-entropy method-based pattern fitting used to confirm validity split-atom model,...
Red/orange-emitting phosphors in the system of La–Sr–Si–O–N were discovered by single-particle diagnosis approach.
A new sialon compound, with the composition (Ba,Ce,Sr)4–mLi(Si,Al)19+2m(O,N)29+m (m = 0.3, n 1), has been discovered. It crystallizes in P3m1 space group, two types of Ba/Sr sites: a ninefold coordinated site located cavities SiN4 tetrahedral framework and sixfold that is substitutional disorder (Si/Al)2(O,N) group. This interesting structural feature gives rise to rare occurrence (Si,Al) atoms fivefold trigonal bipyramidal configuration (O,N) anions, as confirmed by high-resolution...
The scattering unit of X-ray crystal structure analysis is changed from atoms to the subshell electrons by atomic orbital (XAO). All in cell are divided into groups XAO analysis. Each treated as an independent pseudo-atom, which enables orbitals (AO's) and electron population each AO expressed a linear combination s/p/d/f be determined. When environmental condition sample varied, transfer among AO's can traced with XAO. It applicable mainly analyses electron-density distribution ionic solids...
Accurate electron-density measurement of SmB(6) at 100, 165, 230 and 298 K, X-ray atomic orbital (XAO) analysis were carried out. The 4f-electron density around Sm 5d electron approximately 1 A from analysed by XAO analysis. is due to the electrons 5d(J = 5/2)Gamma(8) orbitals which stem e(g) in strong field approximation. change populations 5d(5/2)Gamma(8) with temperature similar that resistivity. Since conduction band consists B-2p according theory, this indicates larger correspond number...
A large shift of the emission colour from blue-green to orange is observed in La<sub>2.5</sub>Ca<sub>1.5−y</sub>Eu<sub>y</sub>Si<sub>12</sub>O<sub>4.5</sub>N<sub>16.5</sub> phosphors, due increased energy transfer between Eu<sup>2+</sup> ions at different crystal sites.
Single crystals of KxFe2−ySe2 are prepared by quenching at various temperatures. The obtained higher temperatures have a surface morphology with mesh-like texture. They show sharp superconducting transition Tc ∼ 32 K large shielding volume fraction. On the other hand, without an onset ∼44 and zero resistivity approximately ∼33 K, they possess island-like regions on larger amount Fe incorporation. In situ high-temperature single-crystal X-ray diffraction measurements tell us...
A novel nitride, Sr2-yEuyB2-2xSi2+3xAl2-xN8+x (x ≃ 0.12, y 0.10) (distrontium europium diboron disilicon dialuminium octanitride), with the space group P62c, was synthesized from Sr3N2, EuN, Si3N4, AlN and BN under nitrogen gas pressure. The structure consists of a host framework Sr/Eu atoms accommodated in cavities. is constructed by linkage MN4 tetrahedra (M = Si, Al) BN3 triangles, contains substitutional disorder described alternative occupation B2 or Si2N on (0, 0, z) axis. B2:Si2N...
Nitrides and oxynitrides isostructural to α-Si