Polyhydric alcohols under high pressure: comparative ultrasonic study of elastic properties.

We carried out an experimental ultrasonic study of polyhydric alcohols with the general chemical formula CH(OH) with an increasing number of OH groups: glycerol ( = 3), erythritol ( = 4), xylitol ( = 5), sorbitol ( = 6). The baric and temperature dependences of the elastic characteristics of these substances in the crystalline and glassy states were studied both under isothermal compression up to 1 GPa and during the isobaric heating of 77-295 K. For glycerol, glasses were obtained at different cooling rates, glass-liquid transitions were studied at different pressures.

Remarkably Stable Glassy GeS Densified at 8.3 GPa: Hidden Polyamorphism, Contrasting Optical Properties, Raman and DFT Studies, and Advanced Applications.

Glassy GeS, densified at 8.3 GPa, exhibits a strongly reduced bandgap, predominantly tetrahedral Ge environment, enhanced chemical disorder and partial 3-fold coordination of both germanium and sulfur, assuming two possible reaction paths under high pressure: (i) a simple dissociation 2Ge-S ⇄ Ge-Ge + S-S and (ii) a chemical disproportionation GeS ⇄ GeS + S. The observed electronic and structural changes remain intact for at least seven years under ambient conditions but are gradually evolving upon heating.

Thermobaric history as a tool to govern properties of glasses: case of dipropylene glycol.

The elastic properties of high- and low-pressure glasses of dipropylene glycol were determined for the first time under conditions of isothermal compression up to 1 GPa at 77 K and isobaric heating of 77-300 K at 0.05 GPa and 1 GPa. A strong dependence of the elastic properties of glasses on their thermobaric history has been revealed: glasses obtained at high pressure have not only higher densities (3.

High-Pressure Synthesis of Cubic ZnO and Its Solid Solutions with MgO Doped with Li, Na, and K.

The possibility of doping ZnO in its metastable rock salt structure with Li, Na, and K intended to act as acceptor dopants was investigated. For the first time, MgZnO alloys and pure ZnO with a rock salt structure doped with Li, Na, and K metals was obtained by high-pressure synthesis from pure oxides with the addition of carbonates or acetates of the corresponding metals as dopant sources. Successful stabilization of the metastable rock salt structure and phase purity were confirmed by X-ray diffraction.

Local structure, thermodynamics, and melting of boron phosphide at high pressures by deep learning-driven ab initio simulations.

Boron phosphide (BP) is a (super)hard semiconductor constituted of light elements, which is promising for high demand applications at extreme conditions. The behavior of BP at high temperatures and pressures is of special interest but is also poorly understood because both experimental and conventional ab initio methods are restricted to studying refractory covalent materials. The use of machine learning interatomic potentials is a revolutionary trend that gives a unique opportunity for high-temperature study of materials with ab initio accuracy.