Structural, electrical and thermistor behavior of BiFeO₃–PbZrO₃ for energy-storage devices

The solid-state reaction technique is used to prepare samples of 0.3BiFeO₃–0.7PbZrO₃ and 0.5BiFeO₃–0.5PbZrO₃. Structural parameters, including percent crystallinity, dislocation density, microstrain and average size of crystallites, are calculated using X-ray diffraction data at room temperature. The scanning electron microscopy micrographs reveal the spherical, densely packed nature of the samples with low porosity. The dielectric constant and dielectric loss increase with the rising content of bismuth ferrite (BiFeO₃) in the materials. The performance of the materials as a negative-temperature-coefficient (NTC) thermistor in the temperature range 300–450°C is discussed. The values of the thermistor constant (i.e. in the range 3911–6247 K) and the range of the sensitivity index (−1 to −9%) confirm the potential use of the samples as NTC thermistors. The frequency-dependent alternating current (AC) conductivity satisfies the universal Jonscher power law. The high density of states is determined from the frequency- and temperature-dependent AC conductivity of the materials.