DYSBR AND DYSI - SYNTHESIS, CRYSTAL-STRUC TURE, AND MAGNETISM

By reaction of Dy2S3 with Dy metal and Br-2 (I-2) at 750 degrees C (90 0 degrees C), single phase crystalline DySBr (DySI) has been synthesiz ed. Crystal structure refinement of DySBr confirms the FeOCl-type stru cture (R = 0.049; space group Pmmn, Z = 2, lattice parameters (in Angs trom>: a = 5.349(2), b = 4.079(2), c = 8.066(2)) which is also ascerta ined for DySI (R = 0.059; lattice parameters (in Angstrom): a = 5.320( 2), b = 4.168(1), c = 9.224(5)). The magnetic susceptibilities (temper ature range 3.4 K - 295 K) can be described on the basis of simple mod els (cubic crystal field, molecular field approximation) above 5 K and 15 K respectively. The deviations at low temperature are assumed to b e related essentially to Dy-Dy exchange interactions which are not ade quately described with the molecular field approach.