[en] An 85 nm-thick morphotropic PbZr_0.52Ti_0.48O₃ (PZT) film grown epitaxially and [001]-oriented onto a SrTiO₃-buffered Si-wafer is investigated using temperature dependent X-ray diffraction. Two phase transitions, at T_rt ∼ 500 K and T_c ∼ 685 K, are evidenced and are attributed to structural phase transitions from monoclinic-like to tetragonal-like phase and from tetragonal to paraelectric phase, respectively. The stronger upper shift of T_rt value with respect to the bulk one and the weakly affected T_c (T_c bulk ∼ 665 K) are explained assuming misfit strain changes when crossing T_rt. This finding opens new perspectives for piezoelectric PZT films in harsh applications.