Eur. Phys. J. Appl. Phys. 45, 20302 (2009)
https://doi.org/10.1051/epjap/2009004

Preparation and electrical properties of high-Curie temperature ferroelectrics

¹ School of Materials Science and Engineering, Jiangsu Polytechnic University, Changzhou, Jiangsu 213164, P.R. China
² Key Laboratory for Polymer Materials, Changzhou, Jiangsu 213164, P.R. China
³ Staff Room of Chemistry, Bengbu Medical College, Bengbu, Anhui 233000, P.R. China

Corresponding author: fangbj@em.jpu.edu.cn

Received: 17 September 2008
Accepted: 14 November 2008
Published online: 31 January 2009

Abstract

()Pb(Fe_0.5Nb_0.5)O₃-xPb(Zr_0.2Ti_0.8)O₃ (PFN-PZT, x = 0.75, 0.80, 0.85) ferroelectric ceramics were prepared by conventional solid-state reaction method via the wolframite precursor route. XRD measurements confirmed that the synthesized PFN-PZT ceramics are of pure tetragonal perovskite structure. With the increase of Pb(Zr_0.2Ti_0.8)O₃ (PZT) content, tetragonality (defined as the ratio of cell parameter c/a) increases slightly accompanied by the variation of cell volume. At the optimized sintering condition of 1175 °C for 2 h, the 0.20PFN-0.80PZT ceramics exhibit the largest value of relative density (93.77%). The PFN-PZT ceramics exhibit first-order ferroelectric phase transition of typical normal ferroelectrics, where the dielectric response peaks are narrow, sharp and without frequency dispersion, and the dielectric constant above Curie temperature (T_C) can be fitted well by Curie law. The sintered PFN-PZT ceramics exhibit high-T_C, and with the increase of PZT content, T_C increases and reaches 368, 394 and 401 °C, respectively. With the increase of PZT content, the P-E ferroelectric hysteresis loops of the PFN-PZT ceramics become narrower accompanied by the decrease of remanent polarization (P_r) and coercive field (E_C). Piezoelectric constant d₃₃ of all the PFN-PZT ceramics is small, less than 10 pC/N.