On the two isostructural series of β-Ln2S3

Single crystals and polycrystalline preparations of sesquisulphides of rare-earth elements in the La-Sm series and also Gd were synthesized and studied roentgenographically. Two types of diffraction patterns were obtained, which point to the possible existence of two isostructural series of βLn2S3, the first containing compounds of rare-earth elements from La to Sm , and the second, Sm and Gd. It is shown that despite the general similarity of the X-ray patterns of these sulphides they differ in the number of reflexes, their position and intensity