Piezoelectric properties of (Na, K)(Nb, Sb)O₃-CaZrO₃thin film grown on Sr₂Nb₃O₁₀perovskite oxide nanosheet at low temperatures

A Sr2Nb3O10 (SNO) nanosheet was deposited on a Pt/Ti/SiO2/Si (Pt-Si) substrate using the Langmuir-Blodgett technique. An SNO monolayer was used as the seed layer for the growth of a crystalline 0.97(Na0.5K0.5)(Nb0.91Sb0.09)O3-0.03CaZrO3 (NKNS-CZ) thin film at a low temperature of 400 °C. The NKNS-CZ thin film grew along the [001] direction, and it had a dense microstructure with an average grain size of 75 nm. The dielectric constant of the film was 250, with a low dielectric loss of 3.5% at 100 kHz. The leakage current density of the Pt/NKNS-CZ top-electrode interface was approximately 1.3 × 10-6 A/cm2 at 0.05 MV/cm. Additionally, a slightly increased leakage density (8.1 × 10-5 A/cm2 at 0.05 MV/cm) was observed at the NKNS-CZ/SNO/Pt-Si bottom-electrode interface. Hence, the film exhibited relatively good insulating properties. The d33 and d33 × g33 values of the thin film were approximately 270 pm/V and 32.9 pm2/N, respectively. These are the largest d33 and d33 × g33 values reported until now. Therefore, the NKNS-CZ thin film shows excellent piezoelectric properties, and it can be used for fabricating thin-film piezoelectric energy harvesters.