Sol-gel processing parameters of Pb0.99Zr0.55Sn0.37Ti0.06Nb0.02O3 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 d(33) as high as 60 pm V-1, being strongly AC field dependent. Double P-E hysteresis loops with maximum polarizations of 30 mu C 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 attributed to a change in nucleation/crystallization mechanism due to Pb diffusion through the Pt during film annealing. (C) 1996 Elsevier Science Limited.