Anomalous grain boundary conduction in BiScO3-BaTiO3 high temperature dielectrics

被引：13

作者：

Li, Linhao ^{[1
]}

Roncal-Herrero, Teresa ^{[2
]}

Harrington, John ^{[2
]}

Milne, Steven J. ^{[2
]}

Brown, Andy P. ^{[2
]}

Dean, Julian S. ^{[1
]}

Sinclair, Derek C. ^{[1
]}

机构：

[1] Univ Sheffield, Dept Mat Sci & Engn, Mappin St, Sheffield, S Yorkshire, England

[2] Univ Leeds, Sch Chem & Proc Engn, Leeds, W Yorkshire, England

来源：

ACTA MATERIALIA | 2021年 / 216卷

基金：

英国工程与自然科学研究理事会;

关键词：

IONIC-CONDUCTIVITY; IMPEDANCE; ELECTROLYTES; MODEL;

D O I：

10.1016/j.actamat.2021.117136

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

A combination of X-ray diffraction, analytical-electron microscopy, differential scanning calorimetry, impedance spectroscopy and electromotive force measurements (for oxide-ion transport number measurements, tion) are used to report on the influence of a small amount of a continuous Bi2O3-rich phase along the grain boundaries in sample composition x = 0.4 (BS0.4BT) of the high temperature dielectric solid solution series, x(BiScO3)-(1-x)(BaTiO3). Its presence produces a dramatic change in conductivity of similar to two orders of magnitude and a switch in tion over the range similar to 600 - 800 degrees C that is not observed for other ceramics with lower BiScO3 content. Below similar to 700 degrees C the grain boundaries in BS0.4BT act as electrically blocking layers and dominate the impedance of the ceramics. In contrast, at > 800 degrees C the grain boundaries become highly conductive due to a polymorphic phase transition to, and melting of delta-Bi2O3 which results in the current percolating along the grain boundaries and therefore avoiding the grains. The value of tion increases from similar to 0.13 at similar to 600 degrees C to near unity at similar to 800 degrees C for BS0.4BT, consistent with oxide ion conduction due to the presence of liquid Bi2O3 at grain boundary regions. This behaviour was reproduced by adding a small excess of 3 wt% Bi2O3 into x = 0.3 (BS0.3BT) samples to induce a Bi2O3-rich grain boundary phase, not otherwise present in this composition. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页数：9