Growth Conditions, Electrical Resistivity, Microhardness and Thermal Properties of PrRh_4.8B₂ Single Crystals Synthesized from High-Temperature Copper Solutions

Abstract

PrRh_4.8B₂ single crystals were prepared from high temperature copper solutions by slow cooling method, using praseodymium tips, rhodium powders and boron powders as starting materials under helium flow. PrRh_4.8B₂ belongs to the orthorhombic system with the space group Fmmm; a=0.9697(4)nm, b=0.5577(2)nm and c=2.564(3)nm. Vickers microhardness and electrical resistivity of the compound were measured, and oxidation resistivity of the compound at high temperature in air was studied. Vickers microhardness (H_V) and the electrical resistivity (ρ) value on (001) plane with the orthorhombic system of PrRh_4.8B₂ were in the range of H_V=6.12-7.32GPa and ρ=670×10^-6Ω·cm, respectively. The oxidation in air of PrRh_4.8B₂ crystals began to proceed at about 590°C. Weight gain of the sample heated up to 1200°C in air is 13% and the identified oxidation product consisted of the PrBO₃ (orthorhombic) and Rh (cubic)