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First-principles Studies of Phase Stability and the Neutral Atomic Vacancies in LiNbO3, NaNbO3 and KNbO3
Published online by Cambridge University Press: 26 February 2011
Abstract
We overall evaluated the enthalpies of formation and the formation energies of neutral vacancies in ANbO3 (A = Li, Na, K) using a plane-wave pseudopotential method within a density functional formalism. The LiNbO3 phase with the LiNbO3-type structure was confirmed to have lower enthalpy of formation than that with perovskite- or ilmenite-type structure. The NaNbO3 (R3c) and KNbO3 (Bmm2 and R3m) phases with the lowest symmetry were found to have the lowest enthalpy of formation. The formation energy of a A vacancy was found to be the lowest under an oxidizing atmosphere and that of an O vacancy was found to be the lowest under a reducing atmosphere. The formation energy of a Nb vacancy was the highest under both oxygen-rich and -poor conditions. These results are in agreement with the empirical rule that B site defects in perovskite-type oxide do not exist.
Keywords
- Type
- Research Article
- Information
- MRS Online Proceedings Library (OPL) , Volume 902: Symposium T – Ferroelectric Thin Films XIII , 2005 , 0902-T10-46
- Copyright
- Copyright © Materials Research Society 2006
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