The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Masaharu Takehara - One of the best experts on this subject based on the ideXlab platform.
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High temperature phase and morphological changes of CVD-SiC films studied using in situ X-Ray Diffractometry
Materials Letters, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu TakeharaAbstract:Phase and morphological changes of polycrystalline, chemical-vapor-deposited β-SiC films on graphite at temperatures up to 2500°C were investigated by in situ X-Ray Diffractometry (XRD). It was demonstrated that XRD using imaging plate was useful for monitoring the changes: the β-SiC transformed into α-SiC at 2200°C and then decomposed and were sublimated to develop protruding dendrite structures of β-SiC on the surface because of temperature gradient there.
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In Situ X-Ray Diffractometry of Cristobalite Formation during High-Temperature Oxidation of SiC Films
Japanese Journal of Applied Physics, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu TakeharaAbstract:We studied the kinetics of β-cristobalite formation with the coexistence of amorphous silica on polycrystalline β-SiC films during high-temperature oxidation in air, by in situ X-Ray Diffractometry using an imaging plate. The kinetics was found to obey parabolic laws. The apparent activation energy Q of cristobalite formation estimated in our experiments suggested a possibility that Q might be significantly larger than reported previously for oxide growth on SiC. Possible causes for this large value were discussed.
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Kinetics of cristobalite growth on polycrystalline SiC film studied using high-temperature in situ X-Ray Diffractometry
Materials Research Bulletin, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu Takehara, Hiroki MasumotoAbstract:The kinetics of cristobalite growth on polycrystalline β-SiC films at 1803 and 1873 K were investigated. Sample films were synthesized on graphite strips via chemical vapor deposition and heated in air by their electric resistance. It was demonstrated that in situ X-Ray Diffractometry using imaging plate was useful for analyzing the growth of the oxide crystals with the coexistence of amorphous silica. The kinetics were found to obey parabolic laws. This is consistent with oxidation kinetics of SiC reported earlier.
Toshiki Kingetsu - One of the best experts on this subject based on the ideXlab platform.
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High temperature phase and morphological changes of CVD-SiC films studied using in situ X-Ray Diffractometry
Materials Letters, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu TakeharaAbstract:Phase and morphological changes of polycrystalline, chemical-vapor-deposited β-SiC films on graphite at temperatures up to 2500°C were investigated by in situ X-Ray Diffractometry (XRD). It was demonstrated that XRD using imaging plate was useful for monitoring the changes: the β-SiC transformed into α-SiC at 2200°C and then decomposed and were sublimated to develop protruding dendrite structures of β-SiC on the surface because of temperature gradient there.
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In Situ X-Ray Diffractometry of Cristobalite Formation during High-Temperature Oxidation of SiC Films
Japanese Journal of Applied Physics, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu TakeharaAbstract:We studied the kinetics of β-cristobalite formation with the coexistence of amorphous silica on polycrystalline β-SiC films during high-temperature oxidation in air, by in situ X-Ray Diffractometry using an imaging plate. The kinetics was found to obey parabolic laws. The apparent activation energy Q of cristobalite formation estimated in our experiments suggested a possibility that Q might be significantly larger than reported previously for oxide growth on SiC. Possible causes for this large value were discussed.
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Kinetics of cristobalite growth on polycrystalline SiC film studied using high-temperature in situ X-Ray Diffractometry
Materials Research Bulletin, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu Takehara, Hiroki MasumotoAbstract:The kinetics of cristobalite growth on polycrystalline β-SiC films at 1803 and 1873 K were investigated. Sample films were synthesized on graphite strips via chemical vapor deposition and heated in air by their electric resistance. It was demonstrated that in situ X-Ray Diffractometry using imaging plate was useful for analyzing the growth of the oxide crystals with the coexistence of amorphous silica. The kinetics were found to obey parabolic laws. This is consistent with oxidation kinetics of SiC reported earlier.
E Koppensteiner - One of the best experts on this subject based on the ideXlab platform.
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Triple crystal x‐ray Diffractometry of periodic arrays of semiconductor quantum wires
Applied Physics Letters, 1993Co-Authors: Václav Holý, E Koppensteiner, Leander Tapfer, G. Bauer, H. Lage, Oliver Brandt, Klaus H. PloogAbstract:Kinematical diffraction theory and the optical coherence formalism have been used for calculating the diffuse x‐ray scattering from periodic quantum wires. The method calculates the distribution of the diffusely scattered intensity in the reciprocal lattice plane. The simulated distributions have been compared with those measured on a InAs/GaAs quantum wire by means of triple crystal x‐ray Diffractometry and a good agreement has been achieved. The method can be applied to studies of internal stress relaxation in quantum wires.
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X-Ray Diffractometry of small defects in layered systems
Journal of Physics D: Applied Physics, 1993Co-Authors: V. Holy, J Kubena, E. Abramof, A. Pesek, E KoppensteinerAbstract:X-Ray diffraction in thin layers and layered systems is described using the optical coherence approach and the semi-kinematical diffraction theory. Two defect models in thin layers are considered-the mosaic structure model and the model of interface roughness. For both defect models the reflection curves of a thin layer and a superlattice have been calculated and compared with double-crystal X-Ray Diffractometry results on superlattices and epitaxial layers. The distribution of the diffusely scattered intensity near a reciprocal lattice point has been calculated theoretically for both models and it has been proved experimentally by double- and triple-crystal Diffractometry of epitaxial layers with mosaic structure. It has been demonstrated that the theory yields a tool for estimating the predominant defect type in a layered structure.
Dimas A. M. Zaia - One of the best experts on this subject based on the ideXlab platform.
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Adsorption of Adenine and Thymine on Zeolites: FT-IR and EPR Spectroscopy and X-Ray Diffractometry and SEM Studies
Origins of Life and Evolution of Biospheres, 2012Co-Authors: Cristine E. A. Carneiro, Ivan G. Souza Junior, Cláudio M. D. Souza, Antonio C. S. Costa, Eduardo Mauro, Cássia T. B. V. Zaia, Joaquin Coronas, Clara Casado, Henrique Santana, Dimas A. M. ZaiaAbstract:The interactions of adenine and thymine with and adsorption on zeolites were studied using different techniques. There were two main findings. First, as shown by X-Ray Diffractometry, thymine increased the decomposition of the zeolites (Y, ZSM-5) while adenine prevented it. Second, zeolite Y adsorbed almost the same amount of adenine and thymine, thus both nucleic acid bases could be protected from hydrolysis and UV radiation and could be available for molecular evolution. The X-Ray Diffractometry and SEM showed that artificial seawater almost dissolved zeolite A. The adsorption of adenine on ZSM-5 zeolite was higher than that of thymine (Student-Newman-Keuls test-SNK p
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Adsorption of cysteine on hematite, magnetite and ferrihydrite: FT-IR, Mössbauer, EPR spectroscopy and X-Ray Diffractometry studies
Amino acids, 2010Co-Authors: Alessandra Paula Vieira, Ivan G. Souza Junior, Eduardo Mauro, Cássia T. B. V. Zaia, Henrique Santana, Graciele Berndt, Andrea Paesano, Antonio Carlos Saraiva Da Costa, Dimas A. M. ZaiaAbstract:In the present paper, the adsorption of cysteine on hematite, magnetite and ferrihydrite was studied using FT-IR, electron paramagnetic resonance (EPR), Mossbauer spectroscopy and X-Ray Diffractometry. Cysteine was dissolved in artificial seawater (two different pHs) which contains the major constituents. There were two main findings described in this paper. First, after the cysteine adsorption, the FT-IR spectroscopy and X-Ray Diffractometry data showed the formation of cystine. Second, the Mossbauer spectroscopy did not show any increase in the amount of Fe2+ as expected due the oxidation of cysteine to cystine. An explanation could be that Fe2+ was oxidized by the oxygen present in the seawater or there occurred a reduction of cystine by Fe2+ generating cysteine and Fe3+. The specific surface area and pH at point of zero charge of the iron oxides were influenced by adsorption of cysteine. When compared to other iron oxides, ferrihydrite adsorbed significantly (p < 0.05) more cysteine. The pH has a significant (p < 0.05) effect only on cysteine adsorption on hematite. The FT-IR spectroscopy results showed that cystine remains adsorbed on the surface of the iron oxides even after being mixed with KCl and the amine and carboxylic groups are involved in this interaction. X-Ray Diffractometry showed no changes on iron oxides mineralogy and the following precipitated substances were found along with the iron oxides after drying the samples: cysteine, cystine and seawater salts. The EPR spectroscopy showed that cysteine interacts with iron oxides, changing the relative amounts of iron oxides and hydroxide.
Kenjiro Ito - One of the best experts on this subject based on the ideXlab platform.
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High temperature phase and morphological changes of CVD-SiC films studied using in situ X-Ray Diffractometry
Materials Letters, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu TakeharaAbstract:Phase and morphological changes of polycrystalline, chemical-vapor-deposited β-SiC films on graphite at temperatures up to 2500°C were investigated by in situ X-Ray Diffractometry (XRD). It was demonstrated that XRD using imaging plate was useful for monitoring the changes: the β-SiC transformed into α-SiC at 2200°C and then decomposed and were sublimated to develop protruding dendrite structures of β-SiC on the surface because of temperature gradient there.
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In Situ X-Ray Diffractometry of Cristobalite Formation during High-Temperature Oxidation of SiC Films
Japanese Journal of Applied Physics, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu TakeharaAbstract:We studied the kinetics of β-cristobalite formation with the coexistence of amorphous silica on polycrystalline β-SiC films during high-temperature oxidation in air, by in situ X-Ray Diffractometry using an imaging plate. The kinetics was found to obey parabolic laws. The apparent activation energy Q of cristobalite formation estimated in our experiments suggested a possibility that Q might be significantly larger than reported previously for oxide growth on SiC. Possible causes for this large value were discussed.
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Kinetics of cristobalite growth on polycrystalline SiC film studied using high-temperature in situ X-Ray Diffractometry
Materials Research Bulletin, 1998Co-Authors: Toshiki Kingetsu, Kenjiro Ito, Masaharu Takehara, Hiroki MasumotoAbstract:The kinetics of cristobalite growth on polycrystalline β-SiC films at 1803 and 1873 K were investigated. Sample films were synthesized on graphite strips via chemical vapor deposition and heated in air by their electric resistance. It was demonstrated that in situ X-Ray Diffractometry using imaging plate was useful for analyzing the growth of the oxide crystals with the coexistence of amorphous silica. The kinetics were found to obey parabolic laws. This is consistent with oxidation kinetics of SiC reported earlier.
