Aging behaviours of CuO modified BaTiO₃ ceramics

Abstract

In order to reduce the sintering temperature and enhance the piezoelectricity, a small amount of CuO was added into BaTiO₃ during sintering. The aging behaviours of these CuO modified BaTiO₃ ceramics were studied systematically. For unpoled ceramic, the P–E loop changes gradually from a normal single-loop curve to a double-loop one with aging. Meanwhile, the S–E loop develops gradually from a normal strain curve to the one with almost zero strain under electric field below 10 kV mm^–1. For poled ceramic, it builds a much stronger and more stable internal bias after aging. The P–E loops shift significantly along the electric field and the strain loop shows high asymmetry with one side of high linearity. A dipolar defect model was proposed to explain these aging behaviours. The defect dipoles consisting of Cu²⁺ occupying B site and oxygen vacancy can reorientate gradually with time to align with the spontaneous polarisation. Then the aligned defect dipoles could provide a strong restoring force on the domain wall motion and thus lead to all the observed aging behaviours.

Keywords:

• Aging
• Barium titanate
• Defect dipole
• Strain
• Double-loop polarisation

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Grant No. 51172128), the Specialised Research Fund for the Doctoral Program of Higher Education (Grant No. 20090131110015) and the Natural Science Foundation of Shandong Province (Grant No. ZR2010EM005).