Elasticity of a Pseudoproper Ferroelastic Transition from Stishovite to Post-Stishovite at High Pressure

by carscat | Jan 12, 2021 | Science Highlights

Elastic moduli (Cij) of single-crystal stishovite and post-stishovite are determined using Brillouin light scattering, impulsive stimulated light scattering, and x-ray diffraction up to 70 GPa. The C12 of stishovite converges with the C11 at ∼55  GPa, where the...

Anisotropic Structural Collapse of Mg3Sb2 and Mg3Bi2 at High Pressure

by carscat | Jan 12, 2021 | Science Highlights

Alloys between Mg3Sb2 and Mg3Bi2 have recently been shown to be exceptional thermoelectric materials due in part to their anomalously low thermal conductivity. In the present study, in situ high-pressure synchrotron X-ray diffraction was used to investigate the...

Synthesis of Molecular Metallic Barium Superhydride: Pseudocubic BaH12

by carscat | Jan 11, 2021 | Science Highlights

Following the discovery of high-temperature superconductivity in the La–H system, we studied the formation of new chemical compounds in the barium-hydrogen system at pressures from 75 to 173 GPa. Using in situ generation of hydrogen from NH3BH3, we synthesized...

An X-ray Diffraction and Raman Spectroscopic Study of the High-Pressure Behavior of Gaspéite (Ni0.73Mg0.27CO3)

by carscat | Jan 11, 2021 | Science Highlights

Here, we present new measurements of the phase stability and lattice compressibility of gaspéite (NiCO3) to 50 GPa. Our study is motivated by our interest in understanding high-pressure carbonate behavior. While carbonates have been extensively studied under...

Thermal Equation of State of Phase Egg (AlSiO3OH): Implications for Hydrous Phases in the Deep Earth

by carscat | Jan 10, 2021 | Science Highlights

Phase egg (AlSiO3OH), an important hydrous phase in the Al2O3–SiO2–H2O ternary system, was found in the superdeep diamond from the mantle transition zone. Here, we have investigated the compressibility and the crystal structural evolution of phase egg using the...

Laser-Induced Crystallization and Phase Transitions of As2Se3 Under High Pressure

by carscat | Jan 8, 2021 | Science Highlights

Utilizing the synchrotron x-ray powder diffraction As2Se3 has been investigated under high pressure in a diamond anvil cell with hydrogen and neon applied as the pressure media. For both systems the amorphous samples were compressed to ca. 2–3 GPa and heated in situ...