Preparation, Oxidation Resistance and Electrical Resistivity of Polycrystalline Single Phase RuB₂ Material by Arc-melt Method

Abstract

A single-phase RuB₂ (orthorhombic, space group Pmmn) polycrystalline material was successfully synthesized by the arc melting method. The condition for obtaining a single-phase RuB₂ material is dependent on the composition and form of the raw materials, namely using the composition of atomic ratio Ru:B = 1:2.1 and using granules Ru and B as the raw materials. The lattice constants of a single-phase RuB₂ obtained by the arc melt method are a = 4.645(1), b = 2.865(1), c = 4.046(1) Å, V = 53.8(1) ų. A thermogravimetric-differential thermal analysis (TG-DTA) for RuB₂ was carried out from room temperature to 1473 K. The oxidation reaction of RuB₂ begins at about 570 K, and the weight gain rate of final oxidation is 29%. Interestingly, the RuB₂ material was found to have a significantly lower oxidation resistance than Ru metal. The product after heating up to 1473 K in air atmosphere is a mixture of RuB_1.1 (RuB) and Ru phases, and B₂O₃ which is probably produced in an amorphous state. The values for electrical resistivity of RuB₂ are in the ranges from 23.3 × 10⁻³ to 102.2 × 10⁻³ Ω ‧ cm.