SYNTHESIS, GROWTH OF MONOCRYSTALS AND PROPERTIES OF THE COMPOUNDS OF PbLnCuS3 (Ln–La, Nd, Sm, Gd, Dy, Er) TYPE

Abstract

Quaternary sulfides of the PbLnCuS3 type (Ln–La, Nd, Sm, Gd, Dy, Er) have been obtained either by melting the elements or through furnace charge, 2PbS+Cu2S+Ln2S3 in a graphite crucible placed in a sealed quartz ampoule at a temperature of 1200–1275 K. Monocrystals of PbSmCuS3 and PbGdCuS3 have been grown by mineralization method. The study of X-ray analysis showed that compounds of PbLnCuS3 type crystallize in the orthorhombic singony (а=8.268.20; b=8.848.80; с=7.967.9Å, space group Pmn21). In a series of PbLnCuS3 compounds, the phenomenon of morphotropy manifests itself, which flows from the exchange of the structural type (PbCuSbS3 KZrCuSe3  Eu2CuS2), i.e. when the radius of the cation Ln changes. Their standard thermodynamic functions have been calculated and the temperature dependences of the magnetic susceptibility have been measured