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Crystallographic Orientation Dependence on Electrical Properties of (Bi, Na)TiO3-based Thin Films



Orientation-engineered (La, Ce) cosubstituted 0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3 thin films were epitaxially deposited on CaRuO3 buffered (LaAlO3)0.3(Sr2AlTaO6)0.35 single-crystal substrates by pulsed laser deposition. The ferroelectric, piezoelectric, dielectric, and leakage current characteristics of the thin films were significantly affected by the crystallographic orientation. We found that the (001)-oriented film exhibited the best ferroelectric properties with remnant polarization Pr = 29.5 μC/cm2 and coercive field Ec = 7.4 kV/mm, whereas the (111)-oriented film demonstrated the largest piezoelectric response and dielectric permittivity. The bipolar resistive switching behavior, which is predominantly attributed to a combined effect of ferroelectric switching and formation/rupture of conductive filaments, was observed. The conduction mechanisms were determined to be ohmic conduction and Poole–Frenkel emission at high- and low-resistance states, respectively, in all the films.