Preparation and dielectric properties of unfilled tungsten bronze ferroelectrics Ba4RETiNb9O30

Series new Ba4RETiNb9O30 (RE=La, Pr, Nd, Sm, Eu, Gd) compounds and ceramics were prepared by solid state reaction method respectively. The phase structure, microstructure, dielectric and ferroelectric properties of obtained ceramics were systematically investigated. The XRD results show that all ceramics have been determined as pure tungsten bronze phase. The dielectric characterization indicates that the former four ceramics are relaxors with strong diffuse phase transition and frequency dispersion, while the latter two ceramics show diffuse phase transition. Phase transition temperatures and tetragonality of tungsten bronze structure increase with the decrease of the radii of rare earth. All ceramics have ferroelectricity, among them Ba4GdTiNb9O30 has the highest remnant polarization (2Pr) of 5.12μC/cm2.