Synthesis and Properties of the Compounds CrLn4S7 (Ln: Gd-Lu).

The title compounds (with the exception of Pm, Eu and Tb for Ln) are obtained by heating mixtures of the elements to 1420- 1470 K for one hour in evacuated ampoules or by reaction of the metal oxides with CS2/H2S at 1070- l 100 K. Furthermore, the se1enides CrLn4Se7 (Ln: Dy, Ho, Er, Yb) are prepared from the binary compounds and FeLn4S7 (Ln: Dy, Ho, Y) are prepared from Fe and Ln2S3 in the presence of HZS at - 1270 K. The sulphides with Ln: Dy-Lu are monoclinic, whereas the sulphides with Ln: La-Tb are hexagonal.