Structural, magnetic and dielectric properties of the novel magnetic spinel compounds ZnCoSnO 4 and ZnCoTiO 4

摘要

The transparent semiconductor Zn2SnO4with cubic spinel structure and the isostructural Zn2TiO4have been magnetically doped with Co2+. ZnCoSnO4and ZnCoTiO4exhibit ferrimagnetism belowTN≈ 13?K andTN≈ 17?K. Ferrimagnetic moments are evident inMvsHcurves belowTNby small hysteresis. Fits to strictly linear Curie-Weiss plots aboveTNgiveμeff≈ 4.86 μBand ≈4.91 μBfor ZnCoSnO4and ZnCoTiO4, above theoretical predictions. Impedance spectroscopy data from sintered ceramic can be fitted with a standard equivalent circuit model based on two RC elements for bulk and GB areas. The relative dielectric permittivity of the bulk is ≈20 and ≈30 for Zn2SnO4and Zn2TiO4. The semiconducting ZnCoSnO4and ZnCoTiO4ceramics exhibit bulk resistivity of ≈1 106?Ω?cm and ≈1 105?Ω?cm at 560?K (287?°C), and bulk activation energies ofEA≈ 1.2?eV and 1.1?eV.