Study and evolution with temperature of the intermediate valence state in CeBe13

CeBe 13 is thought to present an intermediate valence state at normal pressure. An interesting feature of this intermetallic compound is that the valence of cerium seems to vary with temperature. The results of an XPS study which confirms the coexistence of the two valence states of cerium (Ce 3+ (4f 1 5d 0 ); Ce 4+ (4f 0 5d 1 )) in CeBe 13 are presented. When the temperature is lowered down to 100K both the lattice parameter behaviour and the XPS spectra may be explained assuming a slight increase of the ratio Ce 4+ /Ce 3+ . In order to ensure the validity of the results, a comparison with other LnBe 13 compounds is given. Electrical resistivity and susceptibility measurements on LnBe 13 (Ln:La, Ce, Gd) are also discussed and this illustrates clearly the particular behaviour of CeBe 13 .