| Summary: | The electrical properties, phase construction, thermal stability and phase transition behavior are investigated in 0.95(K _0.49 Na _0.49 Li _0.02 )(Ta _0.2 Nb _0.8 )O _3 –0.05BaZrO _3 with 2 wt% MnO _2 (KNNLT-BZM) lead-free epitaxial ferroelectric film on LaNiO _3 (LNO)-coated SrTiO _3 (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 MnO _2 doping can effectively suppress its leakage current, which greatly improves the electrical performance featured by a lower leakage value of 8 × 10 ^–11 A cm ^−2 , a twice remnant polarization of 44.7 μ C 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 ( T _Mix-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.
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