γ-BaBO: High-Pressure High-Temperature Polymorph of Barium Borate with Edge-Sharing BO Tetrahedra.

The α- and β-modifications of barium metaborate are important functional materials used in optoelectronic devices. A new theoretically predicted modification of BaBO has been synthesized under conditions of 3 GPa and 900 °C, using the DIA-type apparatus. The new high-pressure modification, γ-BaBO, crystallizes in a centrosymmetrical group of monoclinic syngony (2/ (#14), = 4.

Experimental and Ab Initio Studies of Intrinsic Defects in "Antizeolite" Borates with a Ba(BO) Framework and Their Influence on Properties.

The porous Ba(BO) framework of the so-called "antizeolite" borates with channels along the axis is capable of accommodating various guest anionic groups, e.g. [BO], [F], [F], and [(Li,Na)F].

Temperature-induced oligomerization of polycyclic aromatic hydrocarbons at ambient and high pressures.

Temperature-induced oligomerization of polycyclic aromatic hydrocarbons (PAHs) was found at 500-773 K and ambient and high (3.5 GPa) pressures. The most intensive oligomerization at 1 bar and 3.

Effect of cation substitution on bridgmanite elasticity: A key to interpret seismic anomalies in the lower mantle.

Seismological observations show that, in some regions of the lower mantle, an increase in bulk sound velocity, interestingly, occurs in the same volume where there is a decrease in shear velocity. We show that this anti-correlated behavior occurs on cation substitution in bridgmanite by making single crystal elasticity measurements of MgSiO3 and (Mg,Fe,Al)(Si,Al)O3 using inelastic x-ray scattering in the ambient conditions. Cation substitution of ferrous iron and aluminum may explain large low shear velocity provinces in the lower mantle.

Boron-doped diamond heater and its application to large-volume, high-pressure, and high-temperature experiments.

A temperature of 3500 degrees C was generated using a diamond resistance heater in a large-volume Kawai-type high-pressure apparatus. Re and LaCrO(3) have conventionally been used for heaters in high-pressure studies but they cannot generate temperatures higher than 2900 degrees C and make in situ x-ray observations difficult due to their high x-ray absorption. Using a boron-doped diamond heater overcomes these problems and achieves stable temperature generation for pressure over 10 GPa.