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

The electrical properties, phase construction, thermal stability and phase transition behavior are investigated in 0.95(K0.49Na0.49Li0.02)(Ta0.2Nb0.8)O3ndash;0.05BaZrO3with 2 wt% MnO2 (KNNLT-BZM) lead-free epitaxial ferroelectric film on LaNiO3 (LNO)-coated SrTiO3 (STO) (001)substrate. 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 times; 10ndash;11A cmminus;2 , a twice remnant polarization of 44.7 mu;C cmminus;2 , and frequency-dependent ferroelectricity between 50 Hz and 10 kHz. Strikingly, the KNNLT-BZM film maintained ferroelectric nature up to 200 deg;C, and exhibit a phase transition from O + T mixed phase to T phase (TMix-T) at 300 deg;C with a high Curie temperature above 440 deg;C. These results suggest great application potentials of KNN-based films in lead-free micro-electronic devices.