Electrical property and phase transition analysis of KNN-based leadfree ferroelectric film

The x-ray diffraction results show that a mixed orthorhombic (O) and tetragonal (T) phase is obtained in KNNLT-BZM film. The MnO2 doping can effectively suppress its leakage current, which greatly improves the electrical performance featured by a lower leakage value of 8 × 10–11A cm−2 , a twice remnant polarization of 44.7 μC cm−2 , and frequency-dependent ferroelectricity between 50 Hz and 10 kHz.

Strikingly, the KNNLT-BZM film maintained ferroelectric nature up to 200 °C, and exhibit a phase transition from O + T mixed phase to T phase (TMix-T) at 300 °C with a high Curie temperature above 440 °C. These results suggest great application potentials of KNN-based films in lead-free micro-electronic devices.