Phase equilibria and magnetic behaviour in the Ce-Ni-Ge system

Several ternary germanides obtained in the Ce-Ni-Ge system were studied by electrical resistivity and magnetization measurements. The compounds Ce2NiGe6, CeNiGe3, Ce3Ni2Ge7 and Ce2Ni3Ge5 order antiferromagnetically respectively below T-N = 10.4, 7.6, 7 and 4.2 K. In other words, the T-N-temperature decreases with Ge-content in this series. On the contrary, CeNiGe and Ce3Ni4Ge4 can be classified as intermediate valence compounds. We present a simple picture for a composition dependence of the Ce-valence in this ternary system. The line between CeNiGe and CeNi2Ge2 connects the compounds where the Ce-valence is purely intermediate or nearly trivalent. (C) 1999 Elsevier Science B.V. All rights reserved.