Relationship between Ferroelectric Property and Crystal Structure of Pb(Zr, Ti, Nb)O3 with High Nb Content

Abstract

Pb(Zr, Ti)O3 (PZT) has been widely used as an actuator, a sensor and ferroelectric memory (FeRAM) and so on, due to its high piezoelectricity and ferroelectric performance. In this study, we focused on Nb-substituted PZT, Pb(Zr, Ti, Nb)O3, with Nb contents of 10∼20 mol%. We examined the dependence of the ferroelectric property on Nb content, and investigated the crystal structure by Rietveld analysis using neutron diffraction data. As a result, it was demonstrated that sintered compacts of Pb(Zr, Ti, Nb)O3 with a single phase of the perovskite structure were successfully prepared when the Nb substitution content was up to 10 mol%. It was also found that the Nb substitution made the grain size smaller, and that the average size was 1∼2 μm. P-E hysteresis measurements clarified that the remanant polarization, Pr, was improved by the 10 mol% Nb substitution although the higher Nb content than 10 mol% resulted in the worse ferroelectric property. From the crystal structure analysis, it was indicated that a distortion in the crystal was relaxed by the Nb substitution and thus the spontaneous polarization was decreased with increasing Nb content.