Author
Kazumasa Sugiyama
Other affiliations: Jilin University, Planetary Science Institute, University of Tokyo
Bio: Kazumasa Sugiyama is an academic researcher from Tohoku University. The author has contributed to research in topics: Anomalous X-ray scattering & Crystal structure. The author has an hindex of 26, co-authored 272 publications receiving 2482 citations. Previous affiliations of Kazumasa Sugiyama include Jilin University & Planetary Science Institute.
Papers published on a yearly basis
Papers
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TL;DR: The dependence of scintillation properties on crystal structure and Al-Ga was discussed in this article, where the Czochralski (Cz) method was used to grow Gd 3 (Al 1 − x Ga x ) 5 O 12 (GAGG) single crystals with various Ga concentration of x ǫ = 2, 2.4 and 2.7.
146 citations
TL;DR: In this article, a planetary ball mill was used to extract magnesium and silicon from mechanically activated serpentine ground for 240 min at room temperature using 1 NHCl and 1 N H 2 SO 4 solutions, respectively.
74 citations
TL;DR: The crystal structure of rutile (TiOz) has been studied at high temperatures up to about 1600°C based on sets of single crystal X-ray diffraction intensities collected on a four-circle diffractometer as mentioned in this paper.
Abstract: The crystal structure of rutile (TiOz) has been studied at high temperatures up to about 1600°C based on sets of single crystal X-ray diffraction intensities collected on a four-circle diffractometer. The thermal expansion coefficients for the a- and c-axes in the measured temperature range were (Xa = 8.9( 1) x 10 - 6 ° C - 1 and (Xc = 11.1(1) x 10- 6 ° C - 1, respec- tively. The thermal response of the octahedra about Ti is such that the thermal coefficient for the four short equatorial Ti - 0 bonds was 8.4(3) x 10- 6oC -1 and for the two long apical Ti - 0 bonds 11.5(3) x 10-6 o C - 1. The rate of thermal expansion of the octahedral shared edge is
72 citations
TL;DR: In this paper, a piezoelectric La3Ta0.5Ga5.5O14 bulk single crystal was grown using the Czochralski technique using X-ray diffraction data with a precision corresponding to an R index of 0.04.
Abstract: New piezoelectric La3Ta0.5Ga5.5O14 bulk single crystals were grown using the Czochralski technique. The crystal structure (space group P321, a=8.228(2), c=5.124(2) A) has been refined using single-crystal X-ray diffraction data with a precision corresponding to an R index of 0.04. Ta atoms were found to be ordered in the octahedral site coordinated by six oxygen atoms.
69 citations
TL;DR: In this paper, the structure of molten silicon has been determined at three temperatures of 1440, 1460 and 1520°C by X-ray diffraction, and the results for the first two neighbors are 6.3 (4.6+1.7) at 1440° C, 5.7 (4 5.5+ 1.2) at 1460° C and 5.8 (4 4.4+1).
Abstract: The structure of molten silicon has been determined at three temperatures of 1440, 1460 and 1520° C by X-ray diffraction. All structure factors indicate a characteristic small hump on the higher wave vector side of the first peak and such specific feature becomes slightly obscure as the temperature increases. A small peak is found in the region between the first (0.245 nm) and second (0.55 nm) main peaks in the pair distribution functions with a shallow minimum at about 0.35 nm. This is not observed in the pair distribution functions for usual molten metals. The coordination numbers in the near-neighbor region have been estimated by applying the interference function refining technique and the results for the first two neighbors are 6.3 (4.6+1.7) at 1440° C, 5.7 (4.5+1.2) at 1460° C and 5.8 (4.4+1.4) at 1520° C. The present structural information is consistent with the recent results of density and electrical resistivity of molten silicon.
64 citations
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Journal Article•
TL;DR: In this paper, the authors presented a method to detect the presence of a tumor in the human brain using EPFL-206025 data set, which was created on 2015-03-03, modified on 2017-05-12
Abstract: Note: Times Cited: 875 Reference EPFL-ARTICLE-206025doi:10.1021/cr0501846View record in Web of Science URL: ://WOS:000249839900009 Record created on 2015-03-03, modified on 2017-05-12
1,704 citations
TL;DR: An account of the mechanistic aspects of hydrothermal zeolite synthesis can be found in this paper, where a review of the most probable mechanistic pathways in Zeolite formation is given.
1,262 citations
TL;DR: The available literature on the crystal structure of the metastable alumina polymorphs and their associated transitions is critically reviewed and summarized in this article, where possible mechanisms for the phase transitions between the different alumina morphological polymorphs also discussed.
Abstract: The available literature on the crystal structure of the metastable alumina polymorphs and their associated transitions is critically reviewed and summarized. All the metastable alumina structures have been identified as ordered or partially ordered cation arrays on the interstitial sites of an approximately close-packed oxygen sublattice (either face-centered cubic or hexagonal close packed). The analysis of the symmetry relations between reported alumina polymorphs having an approximately face-centered cubic packing of the oxygen anions allows for an exact interpretation of all the complex domain structures that have been observed experimentally. Possible mechanisms for the phase transitions between the different alumina polymorphs also are discussed.
1,188 citations
TL;DR: The preparation of aluminophosphate zeolites and zeolite analogues by using ionic liquids and eutectic mixtures, leading to four zeotype frameworks under different experimental conditions is reported.
Abstract: The challenges associated with synthesizing porous materials1 mean that new classes of zeolites (zeotypes)—such as aluminosilicate zeolites2,3 and zeolite analogues4—together with new methods of preparing known zeotypes5, continue to be of great importance. Normally these materials are prepared hydrothermally with water as the solvent in a sealed autoclave under autogenous pressure6. The reaction mixture usually includes an organic template or ‘structure-directing agent’ that guides the synthesis pathway towards particular structures. Here we report the preparation of aluminophosphate zeolite analogues by using ionic liquids7 and eutectic mixtures8. An imidazolium-based ionic liquid acts as both solvent and template, leading to four zeotype frameworks under different experimental conditions. The structural characteristics of the materials can be traced back to the solvent chemistry used. Because of the vanishingly low vapour pressure of ionic liquids, synthesis takes place at ambient pressure, eliminating safety concerns associated with high hydrothermal pressures. The ionic liquid can also be recycled for further use. A choline chloride/urea eutectic mixture8 is also used in the preparation of a new zeotype framework.
1,135 citations