Phase transformation and electrical properties of la-modified Pb(Zr, Sn, Ti)O3 antiferroelectric ceramics

Phase transformation and electrical properties of lanthanum-modified lead zircono-stanno-titanate (Ph1-xLa2x/3) (Zr0.6Sn0.3Ti0.1) O-3(0.00less than or equal toxless than or equal to0.12, PLZSnT) ceramics with a composition near antiferroelectrie/ferroelectric (AFE/FE) phase boundary were investigated by dielectric spectroscopy, Sawyer-Tower polarization technique, and X-ray diffraction. It was found that, as lanthanum content increases I the ferroelectric rhombohedral phase( x = 0. 00, FER) transforms to antiferroelectric tetragonal (0.03less than or equal toxless than or equal to0.09), and cubic phase( x = 0. 12, PE). In the phase diagram of the PLZSnT system with x = 0.06, AFE(t) region has been extended to 18 at% Ti. A diffused AFE-->PE phase transition with dielectric frequency dispersion, is observed in PLZSnT specimens with high Zr and high Sn contents, which is proved to he an antiferroelectric relaxor. A kind of "slant, narrow" double hysterisis loops, and a peculiar "triple hysteresis loops" were observed in the specimens with a composition near AFE/FE phases boundary due to the coexistence of FE and AFE phases. Effects of lanthanum modification on the phase transformation and electrical properties of Ph( Zr, Sri, Ti) O-3 AFE ceramics were discussed based upon the tolerance factor and lattice structure of AFE phase.