Computer modeling of point defects, impurity self-ordering effects and surfaces in advanced perovskite ferroelectrics

Autor(en): Borstel, G
Kotomin, EA
Eglitis, RI
Heifets, E
Stichwörter: AB-INITIO; ATOMISTIC SIMULATION; DOPED KTAO3; F-CENTERS; FIRST-PRINCIPLES; HARTREE-FOCK CALCULATIONS; KNBO3 CRYSTALS; Physics; Physics, Multidisciplinary; SCANNING-TUNNELING-MICROSCOPY; SEMIEMPIRICAL CALCULATIONS; SRTIO3
Erscheinungsdatum: 2000
Herausgeber: POLISH ACAD SCIENCES INST PHYSICS
Journal: ACTA PHYSICA POLONICA A
Volumen: 98
Ausgabe: 5
Startseite: 469
Seitenende: 481
Zusammenfassung: 
The calculated optical properties of basic point defects - F-type centers and hole polarons - in KNnO(3) perovskite crystals are used for the interpretation of available experimental data. The results of quantum chemical calculations for perovskite KNbxTa1-xO3 solid solutions are presented for x = 0, 0.125, 0.25, 0.75, and 1. An analysis of the optimized atomic and electronic structure clearly demonstrates that several nearest Nb atoms substituting for Ta in KTaO3 - unlike Ta impurities in KNbO3 - reveal a self-ordering effect, which probably triggers the ferroelectricity observed in KNbxTa1-xO3. Lastly, the (110) surface relaxations are calculated for SrTiO3 and BaTiO3 perovskites. The positions of atoms in 16 near-surface layers placed atop a slab of rigid ions are optimized using the classical shell model. Strong surface rumpling and surface-induced dipole moments perpendicular to the surface are predicted for both the O-terminated and Ti-terminated surfaces.
Beschreibung: 
International Conference on Condensed Matter Physics, JASZOWIEC, POLAND, MAY 17-20, 2000
ISSN: 05874246
DOI: 10.12693/APhysPolA.98.469

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