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

Accelerating materials discovery and design: computational study of the structure and properties of materials

“…Since the Re 7 B 3 phase is always above the tie-line of ReB 2 and Re 3 B, and above the tieline of Re 2 B and Re 3 B, we can tentatively identified the Re 2 B_#2 and Re 2 B_#3 structures as the candidates for the two new phases, i.e. phase A and B, discovered in recent synthesis experiments[Juarez-Arellanoa et al, 2013] under high pressures and high temperatures. The transition pressures from our calculation at T = 0 K, 55 GPa and 80 GPa, are higher than the observed experimental pressures.…”

“…-B system during the reaction of elemental rhenium and boron at high pressure and high temperature conditionshas also been observed[Juarez-Arellanoa et al, 2013]. At around 15 GPa and 1500K, extra reflections appeared in the powder x-ray diffraction pattern (XRD), which cannot be assigned to any previously reported Re-B phases, or to any boron phases.…”

“…Re 3 B, Re 7 B 3 and ReB 2 have been synthesized experimentally [Telegus, 1969]. In addition to being superconductors [Strukova et al, 2001;Kawano et al, 2003], these compounds have been intensively investigated for potential applications as ultra-hard materials [Chung et al, 2007;Dubrovinskaia et al, 2007;Qin et al, 2008;Juarez-Arellanoa et al, 2013]. It was reported by Chung et al that ReB 2 can be synthesized under ambient pressure with a hardness of 48 GPa, which makes it one of the hardest compounds on earth.…”

“…However, the validity of these results was questioned [Dubrovinskaia et al, 2007] and one of the later experiments [Qin et al, 2008] showed that ReB 2 has a hardness of about 20 GPa and does not belong to the class of ultra-hard materials. Recently [Juarez-Arellanoa et al, 2013], the hardness of Re 7 B 3 and Re 3 B has been measured experimentally.…”

“…At around 15 GPa and 1500K, extra reflections appeared in the powder x-ray diffraction pattern (XRD), which cannot be assigned to any previously reported Re-B phases, or to any boron phases. Therefore the extra peaks indicate the formation of a new phase, referred to as phase A in Ref [Juarez-Arellanoa et al, 2013]…”