New vacancied and Dy3+-doped molybdates – Their structure, thermal stability, electrical and magnetic properties

Abstract

Microcrystalline samples of new Cd1–3xDy2x⌷xMoO4 solid solution with limited homogeneity (0<x≤0.2222) and cationic vacancies (denoted as ⌷) were prepared by a high-temperature solid state reaction. The XRD data and SEM analysis showed that as-prepared ceramics crystallize in the tetragonal scheelite type symmetry (space group I41/a) with the crystallite size varying between ~2 and ~20µm. A systematic change in lattice constants, a and c, as well as in lattice parameter ratio c/a with an increase of Dy content was observed. Dy-doped molybdates are paramagnets with the antiferromagnetic short-range interaction and spin-orbit coupling. Optical and electrical investigations proved Cd1–3xDy2x⌷xMoO4 solid solution to be in the insulating state of Eg>3eV at room temperature and the thermally activated conduction of the Arrhenius-type above 350K. Moreover, the I-V characteristics provided the evidence of symmetrical and non-linear behavior typical of charge carrier emission weakly induced by the temperature. Relative dielectric permittivity εr below 10 as well as loss tangent tanδ below 0.15 do not substantially depend both on the temperature in the range of 76–400K and the frequency in the range of 5·102–1·106Hz. These results are interpreted in the framework of the acceptor and donor vacancy centers.