Crystal structure of erbium palladium arsenic, ErPdAs

Abstract

AsErPd, orthorhombic, Pnma (no. 62), a = 6.9600(9) A, b = 4.082(2) A, c = 7.862(2) A, V = 223.4 A 3 , Z =4 , Rgt(F) = 0.039, wRref(F) = 0.042, T =2 93 K. Source of material Polycrystalline sample of the ternary arsenide ErPdAs was prepared from the pure elements: amorphous -As as powder, erbium and palladium as ingots, all supplied with minimum purity grade of 99.99 %. Powder and freshly filed chips of the constituents in the nominal ratio of Er:Pd:As = 1:1:1 were mixed together and pressed into pellets. A small excess of arsenic (1 at. %) was added to compensate for possible evaporation losses during the arc melting process. Prior to melting in an arc furnace under Ti/Zr-gettered argon atmosphere, the pellets (about 1 g each) were pre-reacted in evacuated silica tubes by gradual heating them up to 1070 K, holding at this temperature for 2 days and then slow cooling down to the room temperature. The cooled buttons were remelted twice to achieve homogeneity. Finally, to reach thermodynamic equilibrium, the sample was placed into an alumina crucible and sealed in a fused silica tube, kept at 1070 K for one month and subsequently quenched into a cold water. After the sample was crushed, air-stable single crystals with prismatic form and metallic luster were extracted and used for structure determination.