The effect of pyrochlore phase on formation mechanism and electrical properties of perovskite PZMN relaxors

Abstract

The reaction mechanism and electrical properties of phase formation of the perovskite Pb[(Mg-x,Zn1-x)(1/3)Nb-2/3]O-3-SrTiO3 (PZMN-ST) were studied. Three major pyrochlore phase types, Pb2Nb2O7, Pb3Nb2O8 and Pb3Nb4O13 were characterized and analyzed to understand their roles in the formation of perovskite PMN, PZN and PZMN phases. The formation of a perovskite phase within PMN relaxors requires the presence of either Pb2Nb2PO7 or Pb3Nb2O8 pyrochlore phases in the mixture and is only slightly dependent on the presence of the stabilizer. On the other hand, the formation of a perovskite phase within PZN or PZMN relaxors requires the presence of both Pb3Nb2O8 pyrochlore phase and stabilizer. The maximum dielectric constant for PMN, PZN and PZMN systems can be obtained with the Pb3Nb2O8 phase present in the starting raw materials because of the benefit of Pb3Nb2O8 to perovskite phase formation.