Synthesis, structure, and magnetic properties of EuAgCd and YbAgCd

New intermetallic compounds EuAgCd and YbAgCd were synthesized in quantitat ive yield by reaction of the elements in sealed tantalum tubes in a high-fr equency furnace. Both compounds were investigated by X-ray diffraction on p owders and single crystals: KHg2 type, Imma, a = 490.41(8), b = 771.0(1), c = 834.4(2) pm, wR2 = 0.0624, 255 F-2 values, 12 variables for EuAgCd, and MgZn2 type, P6(3)/mmc, a = 584.66(5), c = 946.83(9) pm, wR2 = 0.0502, 187 F -2 values, 11 variables for YbAgCd. Owing to the very small difference in s cattering power, no long range ordering of the silver and cadmium atoms is evident from. the X-ray data, although Ag-Cd ordering is expected. The silv er and cadmium atoms randomly occupy the mercury and zinc positions of the KHg2 and MgZn2 type structures, respectively. In EuAgCd the [AgCd] lsubstru cture consists of strongly puckered, orthorhombically distorted Ag-3 Cd-3 h exagons, while a three-dimensional network of face- and corner-sharing tetr ahedra is observed in YbAgCd. The rare earth atoms fill the space between t he Ag3Cd3 hexagons (EuAgCd) or within the three-dimensional tetrahedral net work (YbAgCd). Magnetic susceptibility measurements indicate Pauli paramagn etism for YbAgCd and Curie-Weiss behavior above 60 K for EuAgCd with an exp erimental magnetic moment of 7.82(3) mu (B)/Eu indicating divalent ytterbiu m and europium. Ferromagnetic ordering at T-C = 28.0(5) K is observed for E uAgCd. At 2 K and 5 T the saturation magnetization is 5.85(5) mu (B)/Eu.