Epitaxial Niobium doped PbZr0.52Ti0.48 (PNZT)/YBa2Cu3O7-x thin film heterostructures consisting of ferroelectric PNZT films with thicknesses over the range d = 1.05 mu m to 0.02 mu m have been successfully fabricated in situ on single crystal LaAlO3(100) using a Nd:YAG pulsed laser deposition technique. Characterization by x-ray diffraction techniques including theta-2 theta scan, rocking curves and oblique phi-scan reveals the epitaxial quality of PNZT thin films down to a thickness of 60 nm. Thickness dependence of ferroelectric and dielectric properties of the PNZT films show that the coercive field E(c) has a d(-2/3) dependence that is in good agreement with a domain nucleation model. For films in the thickness range d = 1.05 mu m to 0.06 mu m the remanent polarization is found to be independent of film thickness. On the other hand the dielectric permittivity is found to decrease monotonically with decreasing film thickness.