Thin films of PbZr0.52Ti0.48O3 (PZT) have been epitaxially grown in situ by pulsed laser deposition on (100)LiF single crystal substrates in view of optical applications, expected from the large difference between the refractive indices of PZT (similar to 2.5) and LiF (1.4). High crystalline quality (001) oriented thin films have been obtained for a deposition temperature ranging in a narrow window (490-510 degrees C), as shown by Xrays diffraction experiments performed in theta-2 theta, theta-scan and phi-scan modes as well as by reflection high energy electron diffraction (RHEED). As well as the structural characteristics, the refractive index (at 632.8 nm) correlates strongly with the deposition temperature. Corresponding to the best epitaxial quality, the highest value of the refractive index, similar to 2.3, has been obtained. Although this value is lower than the one of the bulk material, the difference with LiF refractive index is quite enough in order to expect optical applications.