ON THE CERIUM VALENCE IN TERNARY COMPOUNDS CEMSB(2) AND CEM'BI-2 - M=MN,FE,CO,NI,CU,ZN,PD,AG,AU AND M'=NI,CU,ZN,AG

Ternary compounds CeMSb(2) and CeM'Bi-2 have been synthesized by are m elting followed by a heat treatment at 400, 600 or 800 degrees C for 3 00 h. Bismuth-containing compounds have been observed for the first ti me. From X-ray powder diffractometry all compounds were found to be is otypic with ZrCuSi2-type. In CeMn0.9Sb2, the manganese sublattice orde rs ferromagnetically at T similar to 130 K, and the cerium sublattice shows additional ordering at similar to 20 K. CeMSb(2) (M=Fe, Ni, Pd, Cu, Ag, Au, Zn) are antiferromagnets below T=12 K. In the paramagnetic regime, the cerium atom adopts the Ce-F-2(5/2) tripositive groundstat e. CeCu0.9Bi2 is also an antiferromagnet, whereas for Ce(Ag,Zn)Bi-2 no magnetic order was encountered. X-Ray absorption spectroscopy shows t hat Ce in all compounds CeMSb(2) and CeMBi(2) is in the trivalent, or nearly trivalent, state.