Showing papers by "Takayuki Narushima published in 1993"

Oxidation of Chemically Vapor‐Deposited Silicon Nitride in Dry Oxygen at 1923 to 2003 K

Abstract: Oxidation of chemically vapor-deposited Si3N4 was studied in dry oxygen between 1923 and 2003 K under a total pressure of 0.1 MPa using a thermogravimetric technique. At 1923 to 1953 K, a parabolic rate mechanism prevailed for the oxidation reaction. From 1973 K, the oxidation reaction exhibited a mixed linear-parabolic rate mechanism. At 2003 K, on the other hand, the oxidation of Si3N4 showed a linear behavior. Both amorphous silica and cristobalite were identified as reaction products on the oxidized Si3N4 surface using X-ray diffraction analysis. The percentage of cristobalite in the surface oxide scale was determined from the X-ray diffraction pattern. It was found that, at 2003 K, only amorphous silica was formed. The parabolic rate constants (Kp) obtained from this study were close to those obtained in the literature.

Phase Diagrams of the Ga2O3–B2O3 and In2O3–B2O3 Binary Systems

Abstract: The solubility of Ga 2 o 3 or In 2 O 3 in liquid B 2 O 3 which is used as a flux for pulling single crystal of III-V compounds has been measured by the sampling method in the temperature range of 973 to 1573 K. The gallium or indium contents in the samples were analyzed by ICP atomic emission spectroscopy. The phase equilibrium in the Ga 2 O 3 -B 2 o 3 or In 2 O 3 -B 2 O 3 binary system has been determined by X-ray diffraction and differential thermal analysis For the precipitates in liquid phase or the binary compounds which were synthesized from pure oxides. The solid phase equilibrated with liquid phase was clarified. The phase diagrams of the Ga 2 O 3 -B 2 o 3 and In 2 O 3 -B 2 O 3 binary systems were constructed