The isovalent susbstitution of Ti⁴⁺ by Zr⁴⁺ in BaZr_xTi_1−xO₃ modifies the dielectric character of ferroelectric BaTiO₃ yielding different behaviours such as relaxor, polar cluster, etc. The dynamic coupling between BaTiO₃ polar nanoregions and BaZrO₃ nonpolar ones as well as microstrain between them are thought to be behind such a rich phase diagram. However, these short-range compositonal variations are elusive to detect and this topic is thus rarely addressed. We have grown epitaxial thin films of BaZr_xTi_1−xO₃ on (0 0 1)-oriented SrTiO₃ substrates by pulsed laser deposition sweeping the entire composition range between BaTiO₃ and BaZrO₃ in increments of 0.1 in x. Several characterization techniques (AFM, TEM, XRD, Raman spectroscopy) were used for this research in order to understand the morphological and structural properties of the deposited films. Ellipsometric measurements allowed the calculation of the band gap energy of the films. This work demonstrates the existence of a heterogeneous distribution in the substitution of titanium by zirconium yielding relaxor and polar cluster nanoregions.