Synthesis and characterization of the nonstoichiometric perovskite-type compound ScRh₃B_x

Polycrystalline samples of ScRh₃B_x (0≤x≤1.0) were synthesized by the arc melting method. The crystal structure is the perovskite-type cubic structure (space group Pm3m) for boron content in the range 0≤x≤1.0 (0-20 at.% B). The lattice parameter a varies linearly from a = 0.3903(1) nm (x = 0) to 0.40799(3) nm (x = 1.0). The micro-Vickers hardness increases with increasing boron content from 1.9 (±0.1) GPa for ScRh₃ (0 at.% B) to 9.9 (±0.1) Gpa for SchRh₃B_1.0 (20 at.% B). Thermogravimetric analysis indicates that the oxidation onset temperature for stoichiometric ScRh₃B is 868 K. A sharp exothermic peak is observed at 1068 K by differential thermal analysis. The weight gain of the sample by heating in air up to 1473 K is 12.7%. The weight gain increases with increasing boron content. All samples in the range 0≤x≤1.0 show a metallic temperature dependence of the resistivity down to 0.5 K. Magnetic susceptibilities also show Pauli paramagnetic behavior and no trace of magnetic transitions on superconductivity in any of the samples.