Computer Modeling of Point Defects, Impurity Self-Ordering Effects and Surfaces in Advanced Perovskite Ferroelectrics

• Authors: G. Borstel , E.A. Kotomin , R.I. Eglitis , E. Heifets
• Languages of publication: EN

Abstracts

EN

The calculated optical properties of basic point defects - F-type centers and hole polarons - in KNbO_{3} perovskite crystals are used for the interpretation of available experimental data. The results of quantum chemical calculations for perovskite KNb_{x}Ta_{1-x}O_{3} 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 KTaO_{3} - unlike Ta impurities in KNbO_{3} - reveal a self-ordering effect, which probably triggers the ferroelectricity observed in KNb_{x}Ta_{1-x}O_{3}. Lastly, the (110) surface relaxations are calculated for SrTiO_{3} and BaTiO_{3} 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.

Keywords

EN

61.72.-y; 71.15.-m; 68.35.-p

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2000
• Volume: 98
• Issue: 5
• Pages: 469-481

Dates

published

2000-11

Contributors

author

G. Borstel

• Universität Osnabrück, Fachbereich Physik, 49069 Osnabrück, Germany

author

E.A. Kotomin

• Universität Osnabrück, Fachbereich Physik, 49069 Osnabrück, Germany

author

R.I. Eglitis

• Universität Osnabrück, Fachbereich Physik, 49069 Osnabrück, Germany

author

E. Heifets

• Materials and Processes Simulation Center, Beckman Institute Caltech, Pasadena, CA 91125, USA