6533b825fe1ef96bd1281c2b
RESEARCH PRODUCT
Quantum chemical modelling of point defects in KNbO3 perovskite crystals
Roberts I. EglitisRoberts I. EglitisG. BorstelEugene A. KotominEugene A. Kotominsubject
Potassium niobateGeneral Computer ScienceChemistryGeneral Physics and AstronomyGeneral ChemistryElectronic structureFerroelectricityCrystallographic defectMolecular physicsComputational Mathematicschemistry.chemical_compoundMechanics of MaterialsComputational chemistryAb initio quantum chemistry methodsVacancy defectGeneral Materials ScienceSolid solutionPerovskite (structure)description
Abstract We present results of semi-empirical quantum chemical calculations for several perovskite KNb x Ta 1−x O 3 (KTN) solid solutions, as well as point intrinsic defects – F centers and hole polarons bound to K vacancy – in KNbO 3 . Method of the intermediate neglect of the differential overlap (INDO) was combined with typically 320-atom supercells and atomic geometry optimization. Analysis of the optimized atomic and electronic structure has clearly demonstrated that several nearest Nb atoms substituting for Ta in KTaO 3 – unlike Ta impurities in KNbO 3 – reveal the self-ordering effect, which probably triggers the ferroelectricity observed in KTN. We predict co-existence of one-site (atomic) and two-site (molecular) polarons with close absorption energies ( ≈1 eV). When available, the INDO results are compared with ab initio calculations. The relevant experimental data are discussed.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2000-06-01 | Computational Materials Science |