Effect of sintering temperature on the phase transition and dielectrical response in the relaxor-ferroelectric-system 0.5PZN-0.5PZT

Relaxor ferroelectrics of 0.5Pb(Zn1/3Nb2/3)O-3-0.5Pb(Zr0.47Ti0.53)O-3 (0.5PZN-0.5PZT) near the morphotropic phase boundary (MPB) were prepared using the conventional oxide mixing method. The influence of sintering temperature on the phase transition and dielectrical response in the relaxor-ferroelectric-system 0.5PZN-0.5PZT has been investigated. X-ray diffraction analysis indicated that the phase of the material changed from an initially rhombohedral structure to a MPB structure and then a tetragonal structure when the sintering temperature is increased from 900 to 1250 degrees C. The corresponding grain size is enlarged from 1.1 mu m for predominantly rhombohedral to 2.5 mu m for more than 60% tetragonal, which obeys the common grain-growth law. The dielectric studies revealed that the indicator of the degree of diffuseness gamma decreased with the increase of the sintering temperature from 900 to 1150 degrees C, indicating that the dielectric relaxor behavior was weakened, while at high sintering temperature above 1250 degrees C, gamma increased subsequently, which was attributed to the Pb vacancy due to the formation of a pyrochlore phase. Raman analysis on the B-site cation order correlates well with the dielectric measurement results. (c) 2007 American Institute of Physics.