Size effect in low grain size neodymium doped PZT ceramics

Low grain size neodymium doped lead zirconate titanate ceramics (PZT) were synthesised via a sol–gel method. The phase content, the crystal structure and the dielectric and ferroelectric properties were investigated in dependence of the microstructure and the zirconium/titanium ratio. The aim of the work was the investigation of the correlation between microstructure and properties at very low grain sizes.Below a critical grain size of 1 μm a significant change of the properties and the phase content was observed. The morphotropic phase boundary shifts towards titanium-rich compositions. The experimental observations were compared with model calculations based on the Devonshire theory concerning the room temperature stability of the rhombohedral and tetragonal phase and the position of the morphotropic phase boundary.