Isothermal section of the phase diagram and crystal structures of the compounds in the ternary system Tm–Cu–Sb at 870 K

Abstract

The isothermal section of the Tm–Cu–Sb phase diagram at 870 K was constructed using X-ray phase analysis. The existence of one ternary compound was confirmed - TmCu1-xGe2 (x = 0.109) (structure type HfCuSi2, space group P4/nmm, Pearson code tP8-0.22, a = 4.24170(2), c = 9.73942(9) Å). New ternary copper antimonides Tm3Cu20+xSb11-x (x = 2) (structure type Dy3Cu20+xSb11-x, space group F-43 m, Pearson code cF272, a = 16.55784(4) Å) and TmCu4–xSb2 (x = 1.065) (structure type ErFe4Ge2 (LTM), space group Pnnm, Pearson code oP14–2.13, a = 7.00565(6), b = 7.83582(6), c = 4.25051(3) Å) were found. The crystal structures of compounds were refined by full-profile Rietveld method using X-ray powder diffraction data. The solubility of the third component in all binary phases was found to be negligible. The crystal structures of known ternary antimonides were analyzed and relationship among the crystal structures of compounds in the ternary system Tm–Cu–Sb was illustrated.