Optimum discharge energy density at room temperature in relaxor K1/2Bi1/2TiO3for green energy harvesting

Lead free polycrystalline K1/2Bi1/2TiO3 (KBT) was prepared by solid state reaction method. Experimentally observed frequencies of Raman modes signified its tetragonal phase and matched reasonably well with theoretically calculated values. The relaxor nature of this material was observed in the temperature dependent real part of permittivity and dielectric loss curve. The value of the degree of diffusiveness was estimated from the modified Curie-Weiss law, which is 1.99, confirmed its relaxor behavior. The validation of this behavior was justified by the Vogel-Fulcher relation. The shoulder in the imaginary part of the modulus (M") and permittivity (Ԑ") spectra revealed the presence of polar nano regions (PNRs). The evidence of PNRs was detectable above freezing temperature which became weaker when the temperature exceeded Tm (temperature at the maximum of dielectric constant). Electric field induced polarization and strain curve showed the stabilization of long range ferroelectric order of the specimen at room temperature. Moreover, we obtained the discharge energy density and strain of 0.46 J/cm3 and 0.12%, respectively, at the maximum application of the electric field of 115 kV/cm at room temperature.