DIELECTRIC-PROPERTIES AND CRYSTAL-STRUCTURES IN TERNARY-SYSTEM PB(MG1/2W1/2)O3-PB(NI1/3NB2/3)O3-PBTIO3 CERAMICS

Over the entire range of composition in ternary system Pb(Mg1/2W1/2)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3(PMW-PNN-PT), crystal structures and dielectric properties were investigated. On the compositional line of 30 mol% PNN content, dielectric relaxation, D-E hysteresis loop and long-range order parameter were measured in order to understand the effect of PMW content. From the results, a morphotropic phase boundary (MPB) was found on the compositional line with 45 to 50 mol% PT content. It was found that the PMW component was incorporated into ordered clusters in solid solutions in a PMW-rich compositional region. The degree of ordering was evaluated by the long-range order parameter S. The relationship between the long-range order parameter S and dielectric properties, especially compositional dependence of Curie temperature, in this system was discussed.