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Issue 29, 2017
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Electronic and protonic conduction in LaFeO3

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Abstract

Perovskite-type LaFeO3 has promising applications as a negative-electrode material for Ni/metal-hydride batteries. To further improve electrode performance, a thorough understanding of its charge-transport mechanisms is required. We use hybrid density functional theory to investigate the structural and electronic properties of bulk LaFeO3, as well as the effect of point defects and polarons on charge transport. Electronic charge localizes in the form of small hole and electron polarons; this self-trapping occurs in the bulk and also in the vicinity of point defects and impurities. We find that oxygen vacancies act as deep donors, while Fe and La vacancies are acceptors with the induced holes trapped as small polarons. Hydrogen interstitials and Ge and Ti impurities, on the other hand, act as donors that can trap small electron polarons. Hydrogen binds strongly to the La and Fe vacancies and hence these defects are detrimental to protonic conduction. We also elucidate how doping with Sr enhances the electrode performance of LaFeO3:Sr impurities substituting on La sites act as acceptors and enable electronic conductivity through hole polarons, with a hopping barrier of 0.39 eV. In addition, Sr impurities suppress the formation of cation vacancies, thereby enhancing proton conductivity.

Graphical abstract: Electronic and protonic conduction in LaFeO3

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Publication details

The article was received on 17 May 2017, accepted on 04 Jul 2017 and first published on 08 Jul 2017


Article type: Paper
DOI: 10.1039/C7TA04330A
Citation: J. Mater. Chem. A, 2017,5, 15367-15379
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    Electronic and protonic conduction in LaFeO3

    Z. Zhu, H. Peelaers and C. G. Van de Walle, J. Mater. Chem. A, 2017, 5, 15367
    DOI: 10.1039/C7TA04330A

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