Electrical and Pyroelectric Properties of K2Pb2Gd2W2Ti4Nb4O30 Ferroelectrics

A polycrystalline sample of K2Pb2Gd2W2Ti4Nb4O30 was prepared by a high-temperature solid-state reaction method. The formation of the single-phase compound (at room temperature) was confirmed by preliminary x-ray structural analysis. The surface morphology recorded by scanning electron microscopy at room temperature exhibits a uniform grain distribution on the surface of the sample with few voids. Studies of the (i) variation of dielectric parameters with temperature (27°C to 430°C) and frequency (1 kHz to 5 MHz) and (ii) temperature dependence of polarization confirmed the existence of ferroelectricity in the material below the transition temperatures. Two dielectric anomalies observed at 304°C and 378°C suggest the existence of phase transitions in the material. The temperature and frequency dependences of electrical parameters of the material exhibit a strong correlation between microstructure and properties of the material. The temperature dependence of the direct-current (dc) conductivity shows the typical Arrhenius and negative temperature coefficient of resistance (NTCR) behavior of the material. The variation of the alternating-current (ac) conductivity with frequency obeys Jonscher’s universal power law. The current variation with temperature shows that the material has high pyroelectric coefficient and figure of merit, and thus it is useful for pyroelectric sensors. Even with a small piezoelectric coefficient (4.5 × 10−12 C/N), the material is confirmed to be ferroelectric.