A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3

Abstract

. et al. (5 more authors) (2014) A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3. Nature Materials, 13 (1). 31 -35. ISSN 147631 -35. ISSN -1122 https://doi.org/10.1038/NMAT3782 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Introductory paragraphOxide ion conductors find important technical applications in electrochemical devices such as solid oxide fuel cells (SOFCs), oxygen separation membranes and sensors 1-9 . Na 1/2 Bi 1/2 TiO 3 (NBT) is a well-known lead-free piezoelectric material; however, it is often reported to possess high leakage conductivity which is problematic for its piezoand ferroelectric applications 10-15 . Here we report this high leakage to be oxide ion conduction due to Bi-deficiency and oxygen vacancies induced during materials processing. Mg-doping on the Ti-site increases the ionic conductivity to ~ 0.01 S cm -1 at 600 o C, improves the electrolyte stability in reducing atmospheres and lowers the sintering temperature. This study not only demonstrates how to adjust the nominal NBT composition for dielectric-based applications, but also, more importantly, gives [10][11][12][13][14][15] . NBT exhibits maximum relative permittivity,  r ~ 3000 at ~ 320 o C (T max ) and possesses a distorted perovskite structure with extensive chemical, cationdisplacement and octahedral tilt disorder. 14 The resulting complex nanodomain structure is well known to facilitate high and temperature stable permittivity behaviour which is suitable for the fabrication of high temperature ceramic capacitors in addition to easy phase switching under the application of a large electric field which creates large strains suitable for actuator applications [10][11][12][13][14][15] . One drawback of NBT for piezoelectric and capacitor applications, however, is its high leakage conductivity 10,11 . The piezoelectric properties and room temperature dc conductivity depend on the nominal starting composition 10,11 , the origin of which has not been resolved. Here we report on the surprising and dramatic sensitivity of the ionic and electronic transport properties of NBT on low levels of A-site nonstoichiometry in the nominal starting composition. We demonstr...

The influence of Bi content on dielectric properties of Bi4–xTi3O12–1.5x ceramics

“…3,4 According to the experimental results, we found Na 0:5 Bi 0:5 TiO 3 (NBT) had maximum relative permittivity of 3,000 at 320 C (T max ) and possessed a distorted perovskite structure with extensive chemical, cation-displacement and octahedral tilt disorder 5,6 in the application of high-temperature, high-permittivity ceramic capacitors. However, NBT had low operating temperature because of its high leakage conductivity, and low Curie temperature, [7][8][9] which limited the application of NBT.…”

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

“…Although the presence of disorder does appear to be a key ingredient, its role in response is still largely unknown and subject of intense research efforts [5][6][7]. One line of research focuses on nanodisordered ferroelectrics, with the aim of developing innovative materials for capacitors, memories, and photonics [8][9][10]. Among these, an important role is played by solidsolution perovskites, which are commonly accepted as a paradigm of disordered ferroelectric crystals [5,11,12].…”

High Ionic Conductivity in a LiFeO2–LiAlO2 Composite Under H2/Air Fuel Cell Conditions

“…[18][19][20][21][22][23][24] As for electrolyte materials for solid oxide fuel cells (SOFCs), the existing typical electrolytes such as yttrium stabilised zirconia (YSZ), gadonilium doped ceria (GDC), Sr-and Mg-doped LaGaO 3 (LSGM) and Y-doped BaCeO 3 /BaZrO 3 are good but also have drawbacks, such as poor mechanical strength, too expensive or with insufficient conductivity at intermediate temperature (500 -700 °C). [1,25] Low cost conductive electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) are still in high demand. Therefore to developed ionic conducting electrolytes based on composite materials taking advantage of the interface effects is a good strategy.…”