Comparative study of microstructure, electric properties and conductivity for NiO and PNN modified Pb(Zn1/3Nb2/3)O3–PbZrO3–PbTiO3 ceramics

•Comparative studies of PZN–PZT + NiO and PNN–PZN–PZT with same content level of Ni ions have been performed.•Both XRD and TEM confirmed NiO-added induces a phase transformation from MPB to tetragonal phase.•Two types of substitution behaviors coexist in the studied systems.

The comparative studies of NiO and Pb(Ni1/3Nb2/3)O3 (PNN) added Pb(Zn1/3Nb2/3)O3–PbZrO3–PbTiO3 (PZN–PZT) with the same content level of Ni ions have been performed. On the basis of the XRD and TEM analysis, it is clear that NiO introduction induces a phase transformation from the morphotropic phase boundary (MPB) to the tetragonal phase side, and the corresponding grain size increases greatly. In comparison, the system with PNN addition remains MPB structure, and the corresponding grain size increases slightly. According to the analysis of temperature dependencies of dielectric constant and AC conductivity, combined with the observed evolution trend of ferroelectric loops, it is reasonable to deduce that two types of substitution behaviors coexist in NiO added PZN–PZT system. The doping Ni2+ ions can not only substitute for Ti4+, Zr4+ and Nb5+ ions in the inequivalence replacement, but also substitute for Zn2+ ions in the equivalence replacement.

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