0000000000485825
AUTHOR
Mohamed Mezouar
Orthorhombic boron oxide under pressure: in situ study by X-ray diffraction and Raman scattering
High-pressure phase of boron oxide, orthorhombic \b{eta}-B2O3, has been studied in situ by synchrotron X-ray diffraction to 22 GPa and Raman scattering to 46 GPa at room temperature. The bulk modulus of \b{eta}-B2O3 has been found to be 169(3) GPa that is in good agreement with our ab initio calculations. Raman and IR spectra of \b{eta}-B2O3 have been measured at ambient pressure, all experimentally observed bands have been attributed to the theoretically calculated ones, and the mode assignment has been performed. Based on the data on Raman shift as a function of pressure, combined with equation-of-state data, the Gr\"uneisen parameters of all experimentally observed Raman bands have been …
X-ray diffraction measurements of Mo melting to 119 GPa and the high pressure phase diagram
In this paper, we report angle-dispersive X-ray diffraction data of molybdenum melting, measured in a double-sided laser-heated diamond-anvil cell up to a pressure of 119 GPa and temperatures up to 3400 K. The new melting temperatures are in excellent agreement with earlier measurements up to 90 GPa that relied on optical observations of melting and in strong contrast to most theoretical estimates. The X-ray measurements show that the solid melts from the bcc structure throughout the reported pressure range and provide no evidence for a high temperature transition from bcc to a close-packed structure, or to any other crystalline structure. This observation contradicts earlier interpretation…
Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions
Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions We report a combined experimental and theoretical study of the melting curve and the structural behavior of vanadium under extreme pressure and temperature. We performed powder x-ray-diffraction experiments up to 120 GPa and 4000 K, determining the phase boundary of the body-centered cubic-to-rhombohedral transition and melting temperatures at different pressures. Melting temperatures have also been established from the observation of temperature plateaus during laser heating, and the results from the density-functional theory calculations. Results obtained from our experiments and calculations a…