Defect chemistry of La{sub 2}Ni{sub 1{minus}x}M{sub x}O{sub 4} (M = Mn, Fe, Co, Cu): Relevance to catalytic behavior
- Univ. of Surrey, Guildford (United Kingdom). Dept. of Chemistry
- I.C.I. Katalco, Billingham (United Kingdom)
Atomistic computer simulation techniques are used to investigate the defect properties of the La{sub 2}Ni{sub 1{minus}x}M{sub x}O{sub 4} (M = Mn, Fe, Co, Cu) layered perovskite which are related to the mode of operation of the catalyst. The theoretical techniques are based upon efficient energy minimization procedures and Mott-Littleton methodology for accurate defect modeling. Effective ionic pairwise interatomic potentials correctly reproduce the tetragonal crystal structure. The formation energy of intrinsic atomic defects of the Schottky and Frenkel type are not particularly favorable. The oxidation of La{sub 2}NiO{sub 4+{delta}} was found to be an exothermic process with charge compensation occurring via hole formation preferentially on the Ni site. The highest solubility, for a range of dopants, is calculated for Sr and Ca, in accord with observation. Hole formation was most favorable for Mn > Fe > Co > Ni(undoped) > Cu, demonstrating that Mn and Fe enhance Ni(III) hole formation, which is believed to be an important factor in the observed catalytic activity.
- OSTI ID:
- 347564
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 9 Vol. 103; ISSN JPCBFK; ISSN 1089-5647
- Country of Publication:
- United States
- Language:
- English
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