Perovskite phase formation, microstructure and improvement of dielectric properties in iron‐containing ferroelectrics

Abstract

Pure perovskite‐phase lead iron scandium niobate, Pb(Fe1/4Sc1/4Nb1/2)O3 (PFScN), ceramics have been prepared by a conventional solid‐state reaction method via a B‐site oxide mixing route. Although synthesis conditions have been tailored to optimization, strong frequency dispersion of the dielectric properties cannot be improved by modifying ceramic processing, which is considered as correlating to the nature of iron‐containing ferroelectrics. Sintering in an O2 atmosphere and MnO2 and Li2CO3 dopings tend to decrease the dielectric loss of the iron‐containing dielectrics. The strong frequency dispersion of the dielectric response and the abnormally recurrent increase of the dielectric constant and loss in the paraelectric region are correspondingly suppressed. This improvement of dielectric properties in the iron‐containing ferroelectrics is interpreted by an electron compensation mechanism, in which the generation of donor electrons is based on different ionization paths. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structure and dielectric property of (1 −x)Pb(Fe1/4Sc1/4Nb1/2)O3–xPbTiO3ceramics prepared via a B-site oxide mixing route

“…The appropriate sintering conditions can be determined based on the analysis of weight loss, densification of the sintered ceramics and electrical properties [3,14,15]. Usually, the dielectric constant increases with the sintering temperature; however, too high sintering temperature does not favour the stabilization of the perovskite phase and induces large dielectric loss.…”

“…For dielectric property characterization, silver paste was coated on both surfaces of the well-polished ceramics and fired at 650 • C for 15 min to provide robust electrodes. Detailed measurement procedures were described elsewhere [3,15].…”

“…The main structural character of relaxor ferroelectrics is the random 4 Author to whom any correspondence should be addressed. occupation of equivalent crystallographic positions of the perovskite structure by heterovalent ions, which destructs the normal ferroelectric phase transition and makes the physical properties of relaxor ferroelectrics similar to those of disordered ferromagnetic materials [3,4]. Despite continuous fundamental investigations and advanced applications of relaxor ferroelectrics nowadays, the nature of their extraordinary properties is not completely understood.…”