Frequency Dependent Ferroelectric Properties of BaZrO3 Modified Sr0.8Bi2.2Ta2O9 Thin Films

Frequency dependent ferroelectric properties were investigated in BaZrO3 (BZ) modified Sr0.8Bi2.2Ta2O9 (SBT) thin films deposited by sol-gel spin coating technique. The polarization versus electric field (P-E) hysteresis loops of pure and doped SBT films were comparatively studied for frequencies ranging from 1 to 100 kHz. It was found that the coercive field (2E(C)) increases and the remanent polarization (2P(r)) decreases with increasing frequency. Such an increasing behavior of 2E(C) is associated with resistance, since domain switching consists of domain wall motion through ferroelectric material. It was found that the frequency dependent coercive field relation obeys the Ishibashi power law. Also, it was noted that the 2P(r) value decreases with a logarithmic function of frequency. These frequency dependent properties are attributed to oxygen vacancies and leakage current, which are enhanced after BZ doping.