Electrical conduction properties of the BZT–BST ceramics

• Main Authors: Satyanarayan Patel, Harekrishna Yadav
• Format: Article
• Language: English
• Published: World Scientific Publishing 2020-12-01
• Series: Journal of Advanced Dielectrics
• Subjects: electrical conductivity; impedance spectroscopy; electric modulus; lead-free
• Online Access: http://www.worldscientific.com/doi/epdf/10.1142/S2010135X20500265

0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Sr0.3)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 contribution is low. The significant contributions of loss result from the response of phase-transition in this temperature range (25–65∘C).