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Fumihiro Wakai - One of the best experts on this subject based on the ideXlab platform.
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Low temperature heat capacity measurements of β-Si3N4 and γ-Si3N4: Determination of the Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4
Journal of the European Ceramic Society, 2020Co-Authors: Norimasa Nishiyama, Suguru Kitani, Yuki Ohta, Eleonora Kulik, Zuzana Netriová, Astrid Holzheid, Zoltán Lenčéš, Hitoshi Kawaji, Fumihiro WakaiAbstract:Abstract Isobaric heat capacities of β-Si3N4 and γ-Si3N4 were measured at temperatures between 1.8 and 309.9 K with a thermal relaxation method. The measured heat capacities of γ-Si3N4 are smaller than those of β-Si3N4 in this temperature range. Using these data, we determined the standard entropies of β-Si3N4 and γ-Si3N4 to be 62.30 J·mol−1 K−1 and 51.79 J·mol−1 K−1, respectively. The Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4 was calculated using these values and thermodynamic parameters reported in previous studies. The obtained Equilibrium Phase transition pressure at 2000 K is 11.4 GPa. It is lower than the experimental pressures at which γ-Si3N4 was synthesized in previous studies. The calculated Clapeyron slope at this temperature is 0.6 MPa K−1, which is consistent with those of theoretical studies.
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Thermal expansion and P-V-T equation of state of cubic silicon nitride
Journal of the European Ceramic Society, 2019Co-Authors: Norimasa Nishiyama, Eleonora Kulik, Astrid Holzheid, Yoshinori Tange, Kotaro Fujii, Masahiro Shiraiwa, Nico A. Gaida, Yuji Higo, Masatomo Yashima, Fumihiro WakaiAbstract:Abstract We performed in-situ X-ray diffraction measurements of polycrystalline cubic silicon nitride samples at high temperatures under atmospheric pressure and at simultaneous high-pressure-temperature conditions. In air, cubic silicon nitride survives metastably up to 1733 K without oxidation. The temperature dependence of the thermal expansion coefficient was determined to be α(T) = a1 + a2T – a3T−2 where a1 = 1.34(6) × 10−5 K−1, a2 = 5.06(44) × 10−9 K−2, and a3 = 0.20(10) K. Using all the experimental data obtained under atmospheric and high pressures, a complete set of parameters of the high-temperature third-order Birch Murnaghan equation of state was obtained: K300,0 = 303(5) GPa, K′300,0 = 5.1(8), and (∂KT,0/∂T)P = –0.017(1) GPa K−1, where K0, K′0, and (∂KT,0/∂T)P are the isothermal bulk modulus, its pressure derivative, and its temperature derivative, respectively. These parameters are necessary to calculate the Equilibrium Phase Boundary between the β and cubic Phases in silicon nitride.
Norimasa Nishiyama - One of the best experts on this subject based on the ideXlab platform.
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Low temperature heat capacity measurements of β-Si3N4 and γ-Si3N4: Determination of the Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4
Journal of the European Ceramic Society, 2020Co-Authors: Norimasa Nishiyama, Suguru Kitani, Yuki Ohta, Eleonora Kulik, Zuzana Netriová, Astrid Holzheid, Zoltán Lenčéš, Hitoshi Kawaji, Fumihiro WakaiAbstract:Abstract Isobaric heat capacities of β-Si3N4 and γ-Si3N4 were measured at temperatures between 1.8 and 309.9 K with a thermal relaxation method. The measured heat capacities of γ-Si3N4 are smaller than those of β-Si3N4 in this temperature range. Using these data, we determined the standard entropies of β-Si3N4 and γ-Si3N4 to be 62.30 J·mol−1 K−1 and 51.79 J·mol−1 K−1, respectively. The Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4 was calculated using these values and thermodynamic parameters reported in previous studies. The obtained Equilibrium Phase transition pressure at 2000 K is 11.4 GPa. It is lower than the experimental pressures at which γ-Si3N4 was synthesized in previous studies. The calculated Clapeyron slope at this temperature is 0.6 MPa K−1, which is consistent with those of theoretical studies.
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Thermal expansion and P-V-T equation of state of cubic silicon nitride
Journal of the European Ceramic Society, 2019Co-Authors: Norimasa Nishiyama, Eleonora Kulik, Astrid Holzheid, Yoshinori Tange, Kotaro Fujii, Masahiro Shiraiwa, Nico A. Gaida, Yuji Higo, Masatomo Yashima, Fumihiro WakaiAbstract:Abstract We performed in-situ X-ray diffraction measurements of polycrystalline cubic silicon nitride samples at high temperatures under atmospheric pressure and at simultaneous high-pressure-temperature conditions. In air, cubic silicon nitride survives metastably up to 1733 K without oxidation. The temperature dependence of the thermal expansion coefficient was determined to be α(T) = a1 + a2T – a3T−2 where a1 = 1.34(6) × 10−5 K−1, a2 = 5.06(44) × 10−9 K−2, and a3 = 0.20(10) K. Using all the experimental data obtained under atmospheric and high pressures, a complete set of parameters of the high-temperature third-order Birch Murnaghan equation of state was obtained: K300,0 = 303(5) GPa, K′300,0 = 5.1(8), and (∂KT,0/∂T)P = –0.017(1) GPa K−1, where K0, K′0, and (∂KT,0/∂T)P are the isothermal bulk modulus, its pressure derivative, and its temperature derivative, respectively. These parameters are necessary to calculate the Equilibrium Phase Boundary between the β and cubic Phases in silicon nitride.
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Determination of the Phase Boundary between the B1 and B2 Phases in NaCl by in situ x-ray diffraction
Physical Review B, 2003Co-Authors: Norimasa Nishiyama, Tomoo Katsura, Ken-ichi Funakoshi, Atsushi Kubo, Tomoaki Kubo, Yoshinori Tange, Yu Ichiro Sueda, Sho YokoshiAbstract:The Equilibrium Phase Boundary between the $B1$ and $B2$ Phases in NaCl was determined at temperatures between 1150 and 2000 K by in situ x-ray diffraction, using a Kawai-type apparatus in a beam line of SPring-8, Hyogo, Japan. The press was oscillated during data acquisition in order to reduce the effect of grain growth on the diffraction pattern of NaCl at high temperature, obtained by the energy-dispersive method with a fixed angle. Forward $(B1$ to $B2)$ and backward $(B2$ to $B1)$ transitions were observed independently at temperatures between 1150 and 1600 K; the $P\ensuremath{-}T$ conditions where these transitions occur fall on a straight line, indicating that there is no kinetic effect between the forward and the backward transitions over this temperature range. The Equilibrium Phase Boundary is represented by the linear equation $P$ $(\mathrm{in}\mathrm{}\mathrm{GPa})=30.6(2)\char21{}0.0053(2)$ $T$ (in K). Liquid NaCl was observed at 20.1 GPa and 2100 K, consistent with the melting curve obtained in a previous study using a laser- heated diamond anvil cell. According to our experimental results, the triple point between $B1,$ $B2,$ and liquid NaCl would be located at $19.7\ifmmode\pm\else\textpm\fi{}0.5\mathrm{GPa}$ and $2050\ifmmode\pm\else\textpm\fi{}50\mathrm{K}.$
Eleonora Kulik - One of the best experts on this subject based on the ideXlab platform.
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Low temperature heat capacity measurements of β-Si3N4 and γ-Si3N4: Determination of the Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4
Journal of the European Ceramic Society, 2020Co-Authors: Norimasa Nishiyama, Suguru Kitani, Yuki Ohta, Eleonora Kulik, Zuzana Netriová, Astrid Holzheid, Zoltán Lenčéš, Hitoshi Kawaji, Fumihiro WakaiAbstract:Abstract Isobaric heat capacities of β-Si3N4 and γ-Si3N4 were measured at temperatures between 1.8 and 309.9 K with a thermal relaxation method. The measured heat capacities of γ-Si3N4 are smaller than those of β-Si3N4 in this temperature range. Using these data, we determined the standard entropies of β-Si3N4 and γ-Si3N4 to be 62.30 J·mol−1 K−1 and 51.79 J·mol−1 K−1, respectively. The Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4 was calculated using these values and thermodynamic parameters reported in previous studies. The obtained Equilibrium Phase transition pressure at 2000 K is 11.4 GPa. It is lower than the experimental pressures at which γ-Si3N4 was synthesized in previous studies. The calculated Clapeyron slope at this temperature is 0.6 MPa K−1, which is consistent with those of theoretical studies.
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Thermal expansion and P-V-T equation of state of cubic silicon nitride
Journal of the European Ceramic Society, 2019Co-Authors: Norimasa Nishiyama, Eleonora Kulik, Astrid Holzheid, Yoshinori Tange, Kotaro Fujii, Masahiro Shiraiwa, Nico A. Gaida, Yuji Higo, Masatomo Yashima, Fumihiro WakaiAbstract:Abstract We performed in-situ X-ray diffraction measurements of polycrystalline cubic silicon nitride samples at high temperatures under atmospheric pressure and at simultaneous high-pressure-temperature conditions. In air, cubic silicon nitride survives metastably up to 1733 K without oxidation. The temperature dependence of the thermal expansion coefficient was determined to be α(T) = a1 + a2T – a3T−2 where a1 = 1.34(6) × 10−5 K−1, a2 = 5.06(44) × 10−9 K−2, and a3 = 0.20(10) K. Using all the experimental data obtained under atmospheric and high pressures, a complete set of parameters of the high-temperature third-order Birch Murnaghan equation of state was obtained: K300,0 = 303(5) GPa, K′300,0 = 5.1(8), and (∂KT,0/∂T)P = –0.017(1) GPa K−1, where K0, K′0, and (∂KT,0/∂T)P are the isothermal bulk modulus, its pressure derivative, and its temperature derivative, respectively. These parameters are necessary to calculate the Equilibrium Phase Boundary between the β and cubic Phases in silicon nitride.
Astrid Holzheid - One of the best experts on this subject based on the ideXlab platform.
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Low temperature heat capacity measurements of β-Si3N4 and γ-Si3N4: Determination of the Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4
Journal of the European Ceramic Society, 2020Co-Authors: Norimasa Nishiyama, Suguru Kitani, Yuki Ohta, Eleonora Kulik, Zuzana Netriová, Astrid Holzheid, Zoltán Lenčéš, Hitoshi Kawaji, Fumihiro WakaiAbstract:Abstract Isobaric heat capacities of β-Si3N4 and γ-Si3N4 were measured at temperatures between 1.8 and 309.9 K with a thermal relaxation method. The measured heat capacities of γ-Si3N4 are smaller than those of β-Si3N4 in this temperature range. Using these data, we determined the standard entropies of β-Si3N4 and γ-Si3N4 to be 62.30 J·mol−1 K−1 and 51.79 J·mol−1 K−1, respectively. The Equilibrium Phase Boundary between β-Si3N4 and γ-Si3N4 was calculated using these values and thermodynamic parameters reported in previous studies. The obtained Equilibrium Phase transition pressure at 2000 K is 11.4 GPa. It is lower than the experimental pressures at which γ-Si3N4 was synthesized in previous studies. The calculated Clapeyron slope at this temperature is 0.6 MPa K−1, which is consistent with those of theoretical studies.
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Thermal expansion and P-V-T equation of state of cubic silicon nitride
Journal of the European Ceramic Society, 2019Co-Authors: Norimasa Nishiyama, Eleonora Kulik, Astrid Holzheid, Yoshinori Tange, Kotaro Fujii, Masahiro Shiraiwa, Nico A. Gaida, Yuji Higo, Masatomo Yashima, Fumihiro WakaiAbstract:Abstract We performed in-situ X-ray diffraction measurements of polycrystalline cubic silicon nitride samples at high temperatures under atmospheric pressure and at simultaneous high-pressure-temperature conditions. In air, cubic silicon nitride survives metastably up to 1733 K without oxidation. The temperature dependence of the thermal expansion coefficient was determined to be α(T) = a1 + a2T – a3T−2 where a1 = 1.34(6) × 10−5 K−1, a2 = 5.06(44) × 10−9 K−2, and a3 = 0.20(10) K. Using all the experimental data obtained under atmospheric and high pressures, a complete set of parameters of the high-temperature third-order Birch Murnaghan equation of state was obtained: K300,0 = 303(5) GPa, K′300,0 = 5.1(8), and (∂KT,0/∂T)P = –0.017(1) GPa K−1, where K0, K′0, and (∂KT,0/∂T)P are the isothermal bulk modulus, its pressure derivative, and its temperature derivative, respectively. These parameters are necessary to calculate the Equilibrium Phase Boundary between the β and cubic Phases in silicon nitride.
L. Cao - One of the best experts on this subject based on the ideXlab platform.
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Vortex-glass superconductivity in a typical weak-link YBa2Cu3O7-y/SiO2 system.
Physical review. B Condensed matter, 1994Co-Authors: Yue Zhao, X. B. Zuge, L. CaoAbstract:Vortex-glass superconductivity is studied in an extreme weak-link system of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{y}}$/${\mathrm{SiO}}_{2}$ composite by measuring the I-V curve in a series of low magnetic fields. The feature of the vortex-glass transition, i.e., the changes of the curvature of the I-V curves from the positive to negative are observed and the Equilibrium Phase Boundary line between the normal and superconducting Phases in the H-T plane is obtained. In the magnetic field lower than 135 Oe, the system shows a magnetic-field-independent scaling behavior; but a magnetic-field-dependent scaling behavior is observed in higher fields. A relatively low value of the dynamical exponent z suggests that the dynamics of vortex glass in the weak-link network system is different from that in the superconducting single-crystal system.
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Coherent behaviour and vortex-glass superconductivity in weak-link system YBa2Cu3O7/SiO2
Physica B-condensed Matter, 1994Co-Authors: Yue Zhao, X.b. Zhuge, H.k. Liu, L. Cao, Shi Xue DouAbstract:Abstract Double-transition, as a typical coherent behaviour, appears in both the resistive and magnetic measurements. The transition is sensitive to the coupling strength between the grains, the magnetic field and the carrying current density. The vortex-glass superconductivity and the scaling behaviour of the I-V curve have been observed. The Equilibrium Phase Boundary line between the normal and superconducting Phase in the H-T plane in the present system is similar to those observed in the epitaxial film of YBCO. However, the dynamical exponents in these two system are different.