Dielectric relaxation study of solid solution of lead magnesium niobate and La-doped bismuth titanate

The diffuse phase transition characteristic of PMN is now believed due to the distribution of ordered and disordered phases on microscopic scales, which can coexist over a broad temperature interval. In this investigation La-doped BT is mixed with PMN to reduce the coupling between polar microregions. Phase analysis exhibits the phase transition of BLT from orthorhombic to cubic phase with lattice parameter ∼20.68 A. Electric field induced polarization demonstrates the decrease in the saturation polarization and small increase in the remanent polarization. Temperature dependence of dielectric constant reveals the presence of relaxor-like permittivity behaviour in 50–120°C temperature range. BLT addition in PMN led into decrease in the dielectric constant from 20,000 (100 Hz) to 800 (100 Hz). The difference in the temperature of ϵ max between 100 Hz and 100 KHz frequencies was found to increase, which is due to increase in the degree of relaxation.