Effect of sintering temperature on dielectric relaxation and Raman scattering of 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 system

Relaxor ferroelectrics of 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) (PMN-35PT) were prepared using the columbite precursor proceeding. The influences of sintering temperature on the phase transition, dielectrical response, and Raman scattering in the relaxor-ferroelectric-system PMN-35PT have been investigated in detail. X-ray diffraction analysis indicated that the phase structure of the materials changed from rhombohedral to tetragonal when the sintering temperature increased from 1000 to 1250 degrees C. The stress relaxation induced by the enlarged grain size was responsible for the phase transition phenomena. The dielectric studies revealed that the indicator of the degree of diffuseness gamma decreased with the increase in the sintering temperatures from 1000 to 1150 degrees C, indicating that the dielectric relaxation behavior was weakened; while at higher sintering temperature above 1200 degrees C, gamma increased subsequently due to the formation of Pb vacancy. The Raman analysis provided another evidence for the phase transition from rhombohedral to the tetragonal according to the intensity changes of A(1g) mode. Meanwhile, the ratios of the relative intensity Nb-O-Mg to that of Nb-O-Nb band revealed the degree of the B-site cation order, and the variation trend of these Raman modes correlate well with the dielectric measurement results.