Solid solution range of boron, microhardness and oxidation resistance of the perovskite type RERh3Bx (RE=Gd, Y, Sc) compounds

摘要

Polycrystalline samples of RERh3B (RE= Gd, Y, Sc),which consists of a reactive RE and high melting point Rh and Belements, are successfully synthesized by the arc melting method.RERh3B compounds have the perovskite type cubic structure(space group Pm3m). Perovskite type phases of GdRh B and YRhB exist in the range of ~0.444 ≤x ≤ 1.000. On the other hand,phase of ScRh B the range of 0≤x≤1.000 (0 to 20 mol% B).ScRh3, in the case of x=0, has AuCu3 type structure; its space groupis also Pm3m. The lattice parameter a in RERh3B depends on x andthe value of a increases with increasing boron content x. The valueof Vickers microhardness of the RERh3B at room temperatureranges from 6 to 10 GPa. According to thermo-gravimetric anddifferential thermal analysis for RERh3B (RE = Gd, Y) heating upto 1200℃ in air, a mixed phase of REBO3 and Rh is identified asan oxidized product. In the case of ScRh3B, the oxidized productconsists of Rh, Sc2 0 3 and ScBO 3.