Intermediate phase with orthorhombic symmetry displacement patterns in epitaxial PbZrO3 thin films at high temperatures

Antiferroelectric PbZrO3 epitaxial thin film with thickness of 50nm grown on the SrTiO3 substrate with SrRuO3 buffer layer was studied by Grazing incidence X-ray diffraction in a wide range of temperatures. Apart from the superstructure reflections characteristic for the antiferroelectric phase, we identify the reflections with pseudocubic coordinates of the form (H+0.5, K+0.5, L). This indicates the presence of structures having orthorhombic symmetry as an effect of anti-phase Pb atoms displacements, which are apparently similar to the ones previously proposed for the rhombohedral high-temperature phase in PbZrxTi1-xO3. For these structures only the domain orientations with displacements parallel to the surface are observed in contrast to the antiferroelectric domains where the parallel to surface Pb displacements are absent. The antiferroelectric phase coexists with the one characterized by (H+0.5, K+0.5, L) reflections in a broad temperature range with the maximal amount of the latter being present at T=150 degrees C.