Optimum discharge energy density at room temperature in relaxor K1/2Bi1/2TiO3 for green energy harvesting

Abstract

Lead-free polycrystalline K1/2Bi1/2TiO3 was prepared by the 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 the permittivity and dielectric loss curve. The value of the degree of diffuseness (1.99) was estimated from the modified Curie–Weiss law confirmed its relaxor behavior. The validation of this behavior was justified by the Vogel–Fülcher relation. The shoulder in the imaginary part of the modulus (M″) and permittivity (ε″) spectra revealed the presence of polar nano regions (PNRs). The evidence of PNRs was detectable above freezing temperatures, and became weaker when the temperature exceeded Tm (temperature at the maximum of the dielectric constant). The electric field-induced polarization and strain curve showed the stabilization of the long-range ferroelectric order of the specimen at room temperature. Moreover, the discharge energy density and strain were 0.46 J cm−3 and 0.12%, respectively, at the maximum application of the electric field of 115 kV cm−1 at room temperature.