ON THE TERNARY CALCIUM-CONTAINING PHASES CAM(X)GA(4-X) (M-PD, PT, CU,AG, AU) WITH BAAL4 STRUCTURE

The intermetallic compounds CaM(x)Ga(4-x) (M drop Pd, Pt, Cu, Ag, Au) were synthesized in order to investigate the stability of the BaAl4 st ructure type in ternary gallium-containing systems. The crystal struct ures have been studied on samples with the composition CaM(0.5)Ga(3.5) , (M drop Cu, Au, Pd, Pt) by means of single-crystal and powder diffra ction methods and have been found to be isotypic to BaGa4 and the homo logous ytterbium compounds (BaAl4 structure type, space group I-4/mmm) . In samples with this composition the transition metal atoms replace the gallium atoms in the sites with tetragonal antiprismatic environme nt. All phases obtained have homogeneity ranges with constant calcium content. The non-linear dependence of the unit cell parameters on comp osition can be explained by gallium-transition metal substitution in v arious positions. The GaM(x)Ga(4-x) compounds are diamagnetic in the t emperature range 100-300 K.