Electrical conduction properties of the BZT-BST ceramics

0.5Ba(Zr_(0.2)Ti_(0.8))O3-0.5(Ba_(0.7)Sr_(0.3))TiO3(BZT-BST)has been explored in recent times for potential applications in energy harvesting,electrocaloric and energy storage.To this end,energy harvesting/conversion and storage applications require an understanding of the conduction and loss mechanisms.The conduction mechanism in BZT-BST ceramics is studied using impedance spectroscopy(IS)at 0.1 Hz−3 MHz and 100−600°C.Impedance study reveals the presence of two types of relaxation processes due to grain and grain boundary contributions.The relaxation time and dc conductivity activation energies are obtained as 1.12/1.3 eV and 1.05/1.2eV for bulk/grain boundary,respectively,and found that oxygen vacancies dominated electrical behavior.The relaxation mechanism follows non-Debye-type behavior.The high resistance of the grain(bulk)in the ferroelectric region does not contribute to the high losses;the losses probably result from the phase transition.Also,BZT-BST ceramics exhibit a negative temperature coefficient of resistance(NTCR)behaviour.From a practical application point of view in the temperature regime of 25-65°C,the loss’s contri-bution is low.The significant contributions of loss result from the response of phase-transition in this temperature range(25-65°C)。