Stress-induced shifting of the morphotropic phase boundary in sol–gel derived Pb(Zr0.5Ti0.5)O3 thin films

The structure evolution of Pb(Zr0.5Ti0.5)O3 thin films with different thicknesses on the Pt(1 1 1)/Ti/SiO2/Si substrates has been investigated using X-ray diffraction and Raman scattering. Differing from Pb(Zr0.5Ti0.5)O3 bulk ceramic with a tetragonal phase, our results indicate that for PZT thin films with the same composition monoclinic phase with Cm space group coexisting with tetragonal phase can appear. It is suggested that tensile stress plays a role in shifting the morphotropic phase boundary to titanium-rich region in PZT thin films. The deteriorated ferroelectric properties of PZT thin films can be attributed mainly to the presence of thin non-ferroelectric layer and large tensile stress.