Effect of different calcination temperatures and post annealing on the properties of 1,3 propanediol based Sol–Gel (Na0.5K0.5)NbO3 (NKN) thin films

► Beneficial effect of post annealing treatment on diol based NKN film was shown. ► Single phase, pore and crack free films were fabricated. ► Effect of a post annealing step on the ferroelectric properties was shown. ► Films with high Ec and high Pr were fabricated with post annealing treatment. ► Low leakage currents were achieved with post annealing treatment. 1,3 Propanediol based Sol–Gel (Na0.5K0.5)NbO3 (NKN) lead-free thin films were synthesized on Pt/Ti/SiO2/Si substrates. Na-acetate, K-acetate, and Nb-pentaethoxide were used as metal precursors and 1,3 propanediol as solvent. The influence of different calcination temperatures on the properties of the NKN thin films was analysed by SEM pictures, XRD, hysteresis and leakage current measurements. Low calcination temperatures led to low leakage currents over the whole electric field range. Based on these findings a calcination at low temperatures was combined with a post annealing step. In this way low leakage currents of 6×10−5A/cm2 at an electric field of 150kV/cm and 2 Pr and 2 Ec values of 26.6μC/cm2 and 214kV/cm, respectively, could be achieved. All films with post annealing treatment were free of pore and crack formation on the surface and crystallized in the single perovskite phase of NKN.