Author
Masahiko Shimada
Other affiliations: Nagoya University
Bio: Masahiko Shimada is an academic researcher from Tohoku University. The author has contributed to research in topics: Crystal structure & Seebeck coefficient. The author has an hindex of 34, co-authored 216 publications receiving 4700 citations. Previous affiliations of Masahiko Shimada include Nagoya University.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, phase changes and the microstructure resulting from low-temperature annealing of yttria-doped tetragonal ZrO2 polycrystals in water were investigated at 65° to 120°C.
Abstract: Phase changes and the microstructure resulting from low-temperature annealing of yttria-doped tetragonal ZrO2 polycrystals in water were investigated at 65° to 120°C. Tetragonal ZrO2 on the surface of the sintered body transformed to the monoclinic phase, accompanied by microcracking. The transformation rate in water, which was much greater than that in air, was first order with respect to surface concentration of tetragonal ZrO2. Nonaqueous solvents with a molecular structure containing a lone-pair electron orbital opposite a proton donor site also greatly enhanced the transformation.
512 citations
TL;DR: In this article, the fracture toughness of dense Ce-TZP ceramics containing about 7 to 16 mol% CeO2 was evaluated using fine powders prepared by the hydrolysis technique.
Abstract: Dense Ce-TZP ceramics containing about 7 to 16 mol% CeO2 were fabricated using fine powders prepared by the hydrolysis technique. The mechanical properties of these ceramics were evaluated. The bending strength of sintered bodies with 10 to 12 mol% CeO2 content and small grain-size was about 800 MPa. Fracture toughness was measured by two different methods; a micro-indentation technique and the chevron notched beam technique. A high fracture toughness was obtained for sintered bodies with 7 to 10% CeO2 content and large grain-size. Fracture toughness and hardness were dependent on CeO2 content and grain-size. These mechanical properties are discussed on the basis of the stability of the metastable tetragonal phase depending on CeO2 content and grain-size.
338 citations
TL;DR: In this article, mixed metal hydroxides with hydrotalcite-structure, [M2+1−xMx3+(OH)2]An−x/n·mH2O (M2 + = Mg2+, Ni2+, Co2+, M3+ = Al3+ Fe3+, An− = CO2−3) were synthesized by coprecipitation.
298 citations
TL;DR: In this article, a solution solide d'oxyde de magnesium et d'aluminium, par decomposition thermique dhydrotalcite synthetique, is described.
Abstract: Preparation d'une solution solide d'oxyde de magnesium et d'aluminium, par decomposition thermique d'hydrotalcite synthetique. Donnees sur l'adsorption de divers anions: CrO 4 2− , HPO 4 2− , HGaO 3 2− , SiO 3 2- , SO 4 2- , HVO 4 2− , Cl − et MnO 4 −
174 citations
TL;DR: In this paper, the addition of Al2O3 to Y2O-3-partially stabilized ZrO2 submicrometer powders consolidated by isostatic hot pressing was noted to yield a substantial increase in bending strength.
Abstract: The addition of Al2O3 to Y2O3-partially stabilized ZrO2 submicrometer powders consolidated by isostatic hot pressing was noted to yield a substantial increase in bending strength. Average bending strength for a 20-percent Al2O3 Y2O3-partially stabilized ZrO2 composite was 2400 MPa, with a fracture toughness of 17 MN m to the -3/2. Microindentation and chevron-notched beam test method results are presented. 9 references.
153 citations
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5,346 citations
TL;DR: This review takes into account the main results achieved up to now, and is focused on the role that microstructural characteristics play on the TZP ceramics behaviour in ball heads, namely mechanical properties and their stability, wear of the UHMWPE paired to TZp, and their influence on biocompatibility.
2,380 citations
TL;DR: High photocatalytic H(2)-production activity is attributed predominantly to the presence of graphene, which serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carriers from CdS nanoparticles.
Abstract: The production of clean and renewable hydrogen through water splitting using photocatalysts has received much attention due to the increasing global energy crises. In this study, a high efficiency of the photocatalytic H2 production was achieved using graphene nanosheets decorated with CdS clusters as visible-light-driven photocatalysts. The materials were prepared by a solvothermal method in which graphene oxide (GO) served as the support and cadmium acetate (Cd(Ac)2) as the CdS precursor. These nanosized composites reach a high H2-production rate of 1.12 mmol h–1 (about 4.87 times higher than that of pure CdS nanoparticles) at graphene content of 1.0 wt % and Pt 0.5 wt % under visible-light irradiation and an apparent quantum efficiency (QE) of 22.5% at wavelength of 420 nm. This high photocatalytic H2-production activity is attributed predominantly to the presence of graphene, which serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carrier...
2,212 citations
TL;DR: In this article, the most recent advances in the synthesis and application of phosphors for white light-emitting diodes (pc-WLEDs) with emphasis specifically on: (a) principles to tune the excitation and emission spectra of the phosphors: prediction according to crystal field theory, and structural chemistry characteristics (e.g. covalence of chemical bonds, electronegativity, and polarization effects of element); (b) pc-W LEDs with phosphors excited by blue-LED chips: phosphor characteristics, structure, and activated ions
Abstract: Phosphor-converted white light-emitting diodes (pc-WLEDs) are emerging as an indispensable solid-state light source for the next generation lighting industry and display systems due to their unique properties including but not limited to energy savings, environment-friendliness, small volume, and long persistence. Until now, major challenges in pc-WLEDs have been to achieve high luminous efficacy, high chromatic stability, brilliant color-rending properties, and price competitiveness against fluorescent lamps, which rely critically on the phosphor properties. A comprehensive understanding of the nature and limitations of phosphors and the factors dominating the general trends in pc-WLEDs is of fundamental importance for advancing technological applications. This report aims to provide the most recent advances in the synthesis and application of phosphors for pc-WLEDs with emphasis specifically on: (a) principles to tune the excitation and emission spectra of phosphors: prediction according to crystal field theory, and structural chemistry characteristics (e.g. covalence of chemical bonds, electronegativity, and polarization effects of element); (b) pc-WLEDs with phosphors excited by blue-LED chips: phosphor characteristics, structure, and activated ions (i.e. Ce 3+ and Eu 2+ ), including YAG:Ce, other garnets, non-garnets, sulfides, and (oxy)nitrides; (c) pc-WLEDs with phosphors excited by near ultraviolet LED chips: single-phased white-emitting phosphors (e.g. Eu 2+ –Mn 2+ activated phosphors), red-green-blue phosphors, energy transfer, and mechanisms involved; and (d) new clues for designing novel high-performance phosphors for pc-WLEDs based on available LED chips. Emphasis shall also be placed on the relationships among crystal structure, luminescence properties, and device performances. In addition, applications, challenges and future advances of pc-WLEDs will be discussed.
1,860 citations
TL;DR: The two main processing techniques, soft and hard machining, are assessed in the light of their possible clinical implications and consequences on the long-term performance of zirconia.
1,696 citations