Sol-gel processing of PNZST thin films on Ti/Pt and Ta/Pt metallizations

Sol-gel processing parameters of Pb_0.99Zr_0.55Sn_0.37 Ti_0.06Nb_0.02O₃ thin films were studied. Effects of H₂O, HNO₃ and formamide additives on solution gelation and film properties were investigated. Thin films were prepared on Ti/Pt and Ta/Pt metallized Si substrates. Film microstructures were characterized using SEM, TEM/EDS and XPS. Film microstructures typically contained 'rosette' structures. Strain response of the films under applied electric fields was measured using a double beam interferometer. A piezoelectric double loop was obtained with an effective d₃₃ as high as 60 pm V^-1, being strongly AC field dependent. Double P-E hysteresis loops with maximum polarizations of 30 μC cm^-3 were measured. Field-induced antiferroelectric to ferroelectric phase switching was observed at 110 kV cm^-1 and reverse switching at 74 kV cm^-1. Films prepared on Ti/Pt yielded better electrical properties. This may be attributed to a change in nucleation/ crystallization mechanism due to Pb diffusion through the Pt during film annealing.