Pulsed laser deposition of single-phase lead-free NKLNST thin films with K- and Na-excess targets

•PLD growth of NKLNST films was first attempted using targets incorporating excess K and Na.•Effects of O2 pressure during the PLD process on the films properties were systematically studied.•Proper amount of excess K (Na) and O2 pressure are key leading to high-quality single-phase films.•Best-quality film was deposited with the target incorporating 20mol% excess K and Na at 1Pa of O2.•Ohmic conduction and SCLC dominate the transport in the film at low and high fields, respectively. Lead-free [(Na0.57K0.43)0.94Li0.06][(Nb0.94Sb0.06)0.95Ta0.05]O3 (NKLNST) thin films were prepared on Pt (111)/Ti/SiO2/Si (001) substrates by pulsed laser deposition. NKLNST ceramic targets incorporating different amounts of excess K and Na were utilized in order to compensate the K and Na evaporation loss during the films deposition process, and the target containing 20mol% excess K and Na was found optimal based on the stoichiometry and crystallinity of the resulting films. With such a target and 1Pa of O2, high-quality NKLNST thin films were deposited, which exhibit a well-crystallized perovskite phase, the densest and smoothest surface and optimum structural and electrical properties, with a remnant polarization Pr of 7.18μC/cm2. Ohmic conduction dominates the transport at low electric fields (