Stability of intrinsic defects and defect clusters in LiNbO{sub 3} from density functional theory calculations

Journal Article · Sat Nov 01 00:00:00 EDT 2008 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.78.174103· OSTI ID:21192475

Haixuan, Xu; Lee, Donghwa; Jun, He; Sinnott, Susan B; Phillpot, Simon R ^[1]; Gopalan, Venkatraman ^[2]; Dierolf, Volkmar ^[3]

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1. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)
2. Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
3. Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

A large experimental body of literature on lithium niobate, a technologically important ferroelectric, suggests that nonstoichiometric defects dominate its physical behavior, from macroscale switching to nanoscale wall structure. The exact structure and energetics of such proposed intrinsic defects and defect clusters remains unverified by either first-principles calculations or experiments. Here, density functional theory (DFT) is used to determine the dominant intrinsic defects in LiNbO{sub 3} under various conditions. In particular, in an Nb{sub 2}O{sub 5}-rich environment, a cluster consisting of a niobium antisite compensated by four lithium vacancies is predicted to be the most stable defect structure, thereby verifying what was thus far a conjecture in the literature. Under Li{sub 2}O-rich conditions, the lithium Frenkel defect is predicted to be the most stable, with a positive defect formation energy (DFE). This is proposed as the underlying reason that the vapor-transport equilibration (VTE) method can grow stoichiometric LiNbO{sub 3}. The effects of temperature and oxygen partial pressure are also explored by combining the DFT results with thermodynamic calculations. These predictions provide a picture of a very rich defect structure in lithium niobate, which has important effects on its physical behavior at the macroscale.

• OSTI ID: 21192475
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 78, Issue 17; Other Information: DOI: 10.1103/PhysRevB.78.174103; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL DEFECTS
DENSITY FUNCTIONAL METHOD
FERROELECTRIC MATERIALS
FORECASTING
FORMATION HEAT
FRENKEL DEFECTS
LITHIUM COMPOUNDS
LITHIUM OXIDES
NANOSTRUCTURES
NIOBATES
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PRESSURE DEPENDENCE
STABILITY
STOICHIOMETRY
TEMPERATURE DEPENDENCE
VAPORS