X-RAY AND MAGNETIC INVESTIGATIONS OF THE POLYCRYSTALLINE COMPOUNDS WITH GENERAL FORMULAZn_xSn_yCr_zSe_4

摘要

Seleno-spinels with the general formula Zn_xSnyCr_zSe_4 (where x + y + z ~ 3) were prepared as polycrystalline samples in the two nominal compositions: Zn_(0.9)Sn_(0.1)Cr_2Se_4 and ZnCr_(1.9)Sn_(0.1)Se_4, using ceramic method. X-ray powder diffraction was used to analyse the obtained phases and to determine their crystal structure and lattice parameters. The obtained single-phase compounds crystallize in the spinel cubic structure - Fd3m. Tin ions are found to occupy both tetrahedral and octahedral sublattices. Chemical compositions of the obtained samples were determined using JEOL-type Scanning Microscope which also revealed a variation in local distribution of cations and the porosity of the samples. The magnetisation data for Zn_xSn_yCr_zSe_4 system, shows that the saturation magnetic moments depend on location of tin ions in crystal lattice of ZnCr_2Se_4. It was found that the magnetic properties correspond well both with the chemical composition and with the crystal structure. PACS: 61.05.cp; 61.66.Fn; 75.30.Cr; 75.50.Ee.