Intermediate Valence State of Cerium in Intermetallics

Ce exhibits the intermediate valence (IV) state both as an element and in its compounds. In the present review characteristic behavior of the materials showing the IV state are described. Then the methods of producing this state: the application of the external pressure, temperature and magnetic field as well as the alloying are being discussed. An identification of the IV state is frequently not a simple goal and the best results can be obtained using a combination of various independent methods. Particular attention is paid to the X-ray spectroscopy, lattice parameters and the magnetic properties. As the examples of the IV state in the Ce compounds the properties of following materials are reported: CeRhSb, CeCu_5In_7 CeAg_6In_6, Sc_(1-x)Ce_xFe₄Al_8 and for comparison Sc_(1-x) Yb_xFe₄Al_8.