Ferroelectric, dielectric and leakage current properties of epitaxial (K,Na)NbO3-LiTaO3-CaZrO3 thin films

• Published in: Journal of electroceramics 2015-06, Vol.34 (4), p.249-254
• Main Authors: Li, Yuan-Hang, Chen, Feng, Gao, Guan-Yin, Xu, Hao-Ran, Wu, Wenbin
• Format: Article
• Language: English
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Crystallography and Scattering Methods; Electrochemistry; Ferroelectrics; Glass; Materials Science; Natural Materials; Optical and Electronic Materials
• ISSN: 1385-3449; 1573-8663
• DOI: 10.1007/s10832-014-9981-6

Epitaxial 0.95(Na 0.49  K 0.49 Li 0.02 ) (Nb 0.8 Ta 0.2 )-0.05CaZrO 3 thin films were deposited under various oxygen pressures (15–45 Pa) and substrate temperatures (600–720 °C) on SrTiO 3 (001) substrates using La 0.7 Sr 0.3 MnO 3 as bottom electrodes. Their microstructures, ferroelectric and dielectric properties were intensively investigated with high-resolution X-ray diffraction (XRD), polarization- electric field hysteresis ( P - E ) measurements and leakage currents ( I - V ) characterizations. It is found that the lattice constant of the films increases with increasing deposition temperature, while it nearly keeps a constant even when the oxygen pressures are changed. The crystallinity of the films shows an increment with increasing oxygen partial pressure. Saturated P - E loops are obtained for all the films. The film fabricated with optimized parameters at 680 °C and 35 Pa displays a dielectric constant of 1185 at 1 kHz, a remnant polarization (2 P r ) of 28.0 μC/cm 2 and a coercive field (2 E c ) of 165.4 kV/cm. I - V results revealed that the ohmic conduction, space charge limited current and Pool-Frenkel model came up as predominant transport mechanism in the films in turn with the increment of applied electric field.