Crystal Structures of the Metal Diborides ReB₂, RuB₂, and OsB₂ from Neutron Powder Diffraction 

Abstract

Crystal structures of the metal diborides ReB2, RuB2, and OsB2 from neutron powder diffraction. Zeitschrift für Anorganische und Allgemeine Chemie, 2010, 636 (9-10)

Lattice stress states of superhard tungsten tetraboride from radial x-ray diffraction under nonhydrostatic compression

“…Thus, it appears that the phase transition is still second order in nature. Because this transition pressure (15 GPa) appears far from the pressure when WB 4 begins to yield (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40), the structural change is not likely to be caused by plastic flow; but instead probably results from changes in optimal bonding under pressure within the elastic regime. In ReB 2 , however, a continuous increase of the c/a ratio was found in regardless of the compression conditions within the measured pressure range.…”

“…37 The Re atoms are arranged in a hexagonal close-packed layer with B atoms occupying all tetrahedral voids. X-ray absorption spectroscopic data showed the B layers become flatten with increasing hydrostatic pressure, indicating a reduced structural rigidity of ReB 2 structure.…”

In situ study of the formation of rhenium borides from the elements at high-(p, T) conditions: Extreme incompressibility of Re7B3 and formation of new phases

“…6 demonstrates that the linear compressibilities are very well reproduced. Due to the good agreement between the DFT model and experimental data, including a state-of-the-art neutron powder diffraction study [48], we believe our model is reliable. For Re 3 B, the agreement between the model calculations and the experimental data is significantly poorer.…”

“…This implies that probably Re 3 B is stabilized by defects or impurities. While for ReB 2 a modern neutron powder diffraction study has been presented, with which the boron atoms can be located unequivocally [48], the structure of Re 3 B has not been studied by neutron diffraction. In the initial studies by Aronsson et al [20,21] the boron atoms were not located, and instead assumed to be located on a Wykoff position 4(c).…”

Balancing Mechanical Properties and Sustainability in the Search for Superhard Materials

“…Incorporating light main group elements with their propensity to form short, directional covalent bonds allows enhanced mechanical response [9]. For example, transition metal borides like ReB 2 [12], OsB 2 [13], and RuB 2 [14] all show ultraincompressibility and high hardness. Re 2 C also yields moderate hardness (H v,exp = 17.5 GPa) [15] while transition metal nitrides like OsN 2 , IrN 2 [16], and Re 3 N [17] also demonstrate respectable properties.…”