Semiconducting phase of hafnium dioxide under high pressure: a theoretical study by quasi-particle GW calculations

Superhard semiconducting optically transparent high pressure phase of boron.

An orthorhombic (space group Pnnm) boron phase was synthesized at pressures above 9 GPa and high temperature, and it was demonstrated to be stable at least up to 30 GPa. The structure, determined by single-crystal x-ray diffraction, consists of B12 icosahedra and B2 dumbbells. The charge density distribution obtained from experimental data and ab initio calculations suggests covalent chemical b...

Optical Study of Semiconducting Non-Molecular Nitrogen Under Pressure

Electronic phase transitions of bismuth under strain from relativistic self-consistent GW calculations

We present quasiparticle self-consistent GW (QSGW ) calculations of semimetallic bulk Bi. We go beyond the conventional QSGW method by including the spin-orbit coupling throughout the self-consistency cycle. This approach improves the description of the electron and the hole pockets considerably with respect to standard density functional theory (DFT), leading to excellent agreement with experi...

Magnetism in hafnium dioxide

Thin films of HfO2 produced by pulsed-laser deposition on sapphire, yttria-stabilized zirconia, or silicon substrates show ferromagnetic magnetization curves with little hysteresis and extrapolated Curie temperatures far in excess of 400 K. The moment does not scale with film thickness, but in terms of substrate area it is typically in the range 150–400 B nm −2. The magnetization exhibits a rem...

Study and Kinetic Modeling of Direct Sulfation of Iranian Limestones by Sulfur Dioxide at High CO2 Partial Pressure

The direct sulfation of three high purity Iranian limestones and one precipitated calcium carbonate from different sources, containing more than 97 % CaCO3, were studied in a specially designed fixed bed reactor under atmospheric pressure, in the presence of excess CO2 to prevent decomposition of CaCO3. Experiments were carried out over a range of particle s...