Polycrystalline samples of RERh3Bx (RE = Gd, Y, Sc), which consists of a reactive RE and high melting point Rh and B elements, are successfully synthesized by the arc melting method. RERh3Bx compounds have the perovskite type cubic structure (space group Pm3m). Perovskite type phases of GdRh3Bx and YRh3Bx exist in the range of approximately 0.444≤x≤1.000. On the other hand, phase of ScRh3Bx exists in 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 group is also Pm3m. The lattice parameter a in RERh3Bx depends on x and the value of a increases with increasing boron content x. The value of Vickers microhardness of the RERh3Bx at room temperature ranges from 6 to 10 GPa. According to thermo-gravimetric and differential thermal analysis for RERh3Bx (RE = Gd, Y) heating up to 1200 °C in air, a mixed phase of REBO3 and Rh is identified as an oxidized product. In the case of ScRh3B, the oxidized product consists of Rh, Sc2O3 and ScBO3.
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