N. Nishiyama

Generation of pressures over 40 GPa using Kawai-type multi-anvil press with tungsten carbide anvils

We have generated over 40 GPa pressures, namely, 43 and 44 GPa, at ambient temperature and 2000 K, respectively, using Kawai-type multi-anvil presses (KMAP) with tungsten carbide anvils for the first time. These high-pressure generations were achieved by combining the following pressure-generation techniques: (1) precisely aligned guide block systems, (2) high hardness of tungsten carbide, (3) tapering of second-stage anvil faces, (4) materials with high bulk modulus in a high-pressure cell, and (5) high heating efficiency.

Thermal expansion of coesite determined by synchrotron powder X-ray diffraction

Thermal expansion of synthetic coesite was studied with synchrotron powder X-ray diffraction in the temperature range of 100–1000xa0K. We determined the unit cell parameters of monoclinic coesite (a, b, c, and β) every 50xa0K in this temperature range. We observed that a and b parameters increase with increasing temperature, while c decreases. The β angle also decreases with temperature and approaches 120°. As a result, the unit cell volume expands by only 0.7% in this temperature range. Our measurements provide thermal expansion coefficients of coesite as a function of temperature: it increases from 3.4u2009×u200910−6 K−1 at 100xa0K to 9.3u2009×u200910−6 K−1 at 600xa0K and remains nearly constant above this temperature. The Suzuki model based on the zero-pressure Mie–Grüneisen equation of state was implemented to fit the unit cell volume data. The refined parameters are

Transformation Toughening by Fracture-Induced Amorphization in Nanopolycrystalline Stishovite

{V_0}

Phase relations in silicon and germanium nitrides up to 98 GPa and 2400°C

V0u2009=u2009546.30(2) Å3,

Equation of State of Polycrystalline Stishovite Across the Tetragonal‐Orthorhombic Phase Transition

Q

Transparent nanocrystalline bulk alumina obtained at 7.7 GPa and 800 degrees C

Qu2009=u20097.20(12)u2009×u2009106 J/mol and