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 Zn 1− x ) 1/3Nb 2/3] O 3-SrTiO 3 (PZMN-ST) were studied. Three major pyrochlore phase types, Pb 2Nb 2O 7, Pb 3Nb 2O 8 and Pb 3Nb 4O 13 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 Pb 2Nb 2O 7 or Pb 3Nb 2O 8 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 Pb 3Nb 2O 8 pyrochlore phase and stabilizer. The maximum dielectric constant for PMN, PZN and PZMN systems can be obtained with the Pb 3Nb 2O 8 phase present in the starting raw materials because of the benefit of Pb 3Nb 2O 8 to perovskite phase formation.