Preparation and dielectric properties of co-contained unfilled tungsten bronze ceramics Ba4RCo0.5Nb9.5O30

Xiaoying Guo,Liang Fang,Changzheng Hu,Nengneng Luo,Chaozhong Sun,Weifeng Zhang,Laijun Liu,Shan Wu

doi:10.1007/s10854-021-06951-x

Abstract

In this study, Ba4RCo0.5Nb9.5O30 (R = La, Nd, Sm, Eu) (BRCN) ceramics were synthesized using a high-temperature solid-state reaction. The XRD refinement results show that ceramic samples are tetragonal tungsten bronze (TTB). As the radius of rare-earth ions decreases, the unit cell volume of BRCN ceramics decreases, and the radius difference between Ba2+ and R ions increase, which results in BO6 octahedral distortion and the Raman peaks shift to high frequency. In addition, as the radius of rare-earth ions decreases, the ionic displacements increase and thus the dielectric constant peak temperature goes up. The high-temperature impedance results show that there exists n-type electronic conduction in the samples. The remanent polarization of the P–E curve at low frequencies increases from 0.470 to 1.038 μC cm−2 as the rare-earth ion radius decreases.

Highlights

The tetragonal tungsten bronze (TTB) structure exist a plurality of ionic positions and has a flexible crystal structure, which has aroused extensive research interest
In order to make the abnormal dielectric peak more significant, we focus on the dielectric constant of the BRCN ceramics measured at the test frequency of 1 MHz and the temperature range of 101-523 K, using used the Curie-Weiss law (Eq (1)) [21] to fit in Fig. 5: εr = C/(T − T0)
Ba4RCo0.5Nb9.5O30 (R = La, Nd, Sm, Eu) unfilled tungsten bronze structural ceramics were prepared by high-temperature solid-state synthesis

Summary

Introduction

The tetragonal tungsten bronze (TTB) structure exist a plurality of ionic positions and has a flexible crystal structure, which has aroused extensive research interest. It is the most striking ferroelectric material after the perovskite structure [1,2,3]. Chen et al used rare-earth elements (Ln = La, Nd, Sm) to replace the A1 site ions of Fe-doped filled tungsten bronze Ba3SrLn2Fe2Nb8O30 and conducted research on dielectric characteristics. A systematic study was conducted on the influence of rare-earth ions on the phase structure, microstructure, and dielectric properties of the ceramics

Experimental procedures

Results and discussion

Conclusions