In a theoretical study of a "defect perovskite" structure of stoichiometry AeTiO(2) (AE = alkaline earth metal, Be, Mg, Ca, Sr, and Ba), we find substantial Ti-Ti bonding tuned by the size of the Ae(2+) cation. The bonding is one-dimensional, partially sigma, partially pi. These formal d(2) systems are expected to be nonmagnetic and metallic. A competing (for same Ae) structural alternative, an...

We report an ab initio study of the mechanical stability of platinum nitride (PtN), in four different crystal structures, the rock salt (rs-PtN), zinc blende (zb-PtN), cooperite and a face centered orthorhombic phase. Only the rs-PtN phase is found to be stable, with a bulk modulus B = 284 GPa. Its electronic density of states shows no band gap making it metallic. The zb-PtN phase does not stab...

PbSe nanocrystals with rock-salt structure are grown on the tips of colloidal CdS and CdSe nanorods. The facets of wurtzite rods provide a substrate with various degrees of reactivity for the growth of PbSe. The presence of dangling Cd bonds may explain subtle differences between nonequivalent facets resulting in the selective nucleation of PbSe only on one of the two tips of each CdS rod. This...

The first step in mining activities is rock excavation in both mine development and production. Constant pressure for cost reduction and creating an improved/safe work environment for personnel has naturally resulted in increased use of mechanical excavation systems in many mining operations. Also, mechanical excavation and mining is more compatible with automation, meaning possibility of reduc...

Relating the synthesis conditions of materials to their functional performance has long been an experience-based trial-and-error process. However, this methodology is not always efficient in identifying appropriate protocol and can lead overlooked opportunities for optimization through simple modifications In work, authors systematically track structural evolution a representative disordered ro...