Enhancement of dielectric and multiferroic properties in Sr-modified 0.7BaTiO3-0.3ZnFe2O4 ceramics

Multiferroic ceramic composites 0.7(Ba1-xSrxTiO3)-0.3ZnFe(2)O(4) (x = 0.0, 0.1, 0.3) were synthesized by easy and inexpensive solid-state reaction technique. The coexistence of tetragonal perovskite BTO(BaTiO3) and cubic spinel ZFO(ZnFe2O4) phases was verified by X-ray diffraction analysis. The crystallite size in the range 32-49 nm was found from XRD data. The substantial growth of microstructural properties (grain growth, motion of grain boundaries, decreases of voids, etc.) leads to the enhancement of electrical and magnetic properties of the samples. The transition temperature (T-r) decreases at the lower temperature around 35-45 degrees C for the replacement of Sr in BTO-ZFO matrix. The variations of dielectric loss with temperature are ascribed to the retarded space polarization. The activation energy of the materials was obtained from the variation of ac conductivity with temperature. The grain and grain boundary resistance was estimated through Nyquist plot which suggest NTCR (Negative temperature coefficient of resistance) behaviour of the material. The conduction of the composite ceramics was related to the charge carriers hopping mechanism. The activation energy was calculated to be in the range of 0.1286-0.0939 eV from temperature dependence of ac conductivity. The M-H measurements showed that the remnant magnetization at low temperatures is significantly enhanced in comparison to pure zinc ferrite (1.35 emu/g) owing to the existence of the Ba1-xSrxTiO3 phase (3.7 emu/g). The remnant polarization was found 12.01 mu C/cm(2) and 4.12 mu C/cm(2) of doped (x = 0.3) and pure sample (x = 0) respectively, and it suggest the relaxor properties of the glossy ferroelectrics.