Toggle Main Menu Toggle Search

Open Access padlockePrints

The Newcastle University research output collection, currently available on ePrints, will shortly be moving to a new open repository platform, Figshare. To prepare for the data migration we have paused adding new content to ePrints, and will resume once the new repository is launched. During this time you will continue to have access to ePrints (but no new content will appear). We will share updates here when available.

Synthesis and characterisation of vanadium doped alkaline earth lanthanum germanate oxyapatite electrolyte

Lookup NU author(s): Dr Stevin PramanaORCiD

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.

Abstract

The crystal chemistry and oxygen conductivity of vanadium-doped apatites of nominal composition [La 8AE 2][Ge 6-xV x]O 26+x/2 (AE = Ca, Sr, Ba; 0 ≤ x ≤ 1.5) were studied to establish their potential as intermediate temperature solid oxide fuel cell (SOFC) electrolytes. Single-phase products obtained for x ≤ 0.5 were found, using a combination of powder synchrotron X-ray and neutron diffraction, to be P6 3/m apatites. The ionic conductivities extracted by complex impedance spectroscopy showed that small vanadium amendments enhanced oxygen mobility at intermediate temperatures (500-700 °C) by more than one order of magnitude, as the incorporation of V 5+ through displacement of Ge 4+ is charge balanced with interstitial O 2- that improves ionic conduction. The most promising composition was La 7.88Ca 2Ge 5.35V 0.65O 26.15 that delivered σ = 3.44 × 10 -4 S cm -1 at 500 °C. The superstoichiometric oxygen was delocalised, without fixed X-ray or neutron scattering centres. Crystal chemistry systematics demonstrate that the Ca-apatite was superior because the relatively small framework expanded the tunnel through reduced (La/AE)O 6 metaprism twisting (φ), ensuring the P6 3/m symmetry was adopted, which favours the passage of O 2- with lower activation energy. © 2012 The Royal Society of Chemistry.

Publication metadata

Author(s): Li H, Baikie T, Pramana SS, Shin JF, Slater PR, Brink F, Hester J, Wallwork K, White TJ

Publication type: Article

Publication status: Published

Journal: Journal of Materials Chemistry

Year: 2012

Volume: 22

Issue: 6

Pages: 2658-2669

Print publication date: 14/02/2012

Online publication date: 19/12/2011

ISSN (print): 0959-9428

ISSN (electronic): 1364-5501

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/c1jm13752b

DOI: 10.1039/c1jm13752b

Altmetrics

Altmetrics provided by Altmetric

Share