Effective Dielectric Loss Reduction and Enhanced Dielectric Temperature Stability of (1-x)BaFe0.5Nb0.5O3-xBiCu0.75W0.25O3 Ceramics

In the present study, a series of lead-free ceramics (1-x)BaFe0.5Nb0.5O3-xBiCu(0.75)W(0.25)O(3) (BFN-xBCW) were synthesized using a solid-state reaction method. The crystallization of all samples in the cubic structure with Pm (3) over bar m space group was confirmed by X-ray diffraction (XRD) results. The calculated and observed patterns exhibited good agreement after Riet-veld refinement. SEM analysis showed that the average grain size of the samples ranged from 0.89 to 1.20 mu m. The sample (1-x)BFN-xBCW (x = 0.01) has the smallest grain size (0.89 mu m). Detailed studies of dielectric properties as a function of temperature and frequency, have provided several interesting properties. As a function of temperature, a dielectric step at low temperature and a dielectric peak at high temperature were observed. The temperature stability was improved by incorporating 1% BCW (x = 0.01). Combining BCW with BFN successfully reduced the dielectric loss. The smallest tan delta value was obtained for x = 0.02 with a moderate epsilon'. As a function of frequency, two steps were observed. The step observed at higher frequencies and lower temperatures is attributed to the Debye-type relaxation process in the grains, while the step observed at low frequency and high temperature range is attributed to the non-Debye Maxwell-Wagner (M-W) polarization effect.