Impurity levels and nonlinear optical properties of doped BaTiO3 from extended cluster LDA calculations
✍ Scribed by M. Actis; F. Michel-Calendini
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 203 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
The electronic structures of some transition-metal ions doping the ferroelectric oxide Ž BaTiO are calculated through the density functional theory framework LCAO-LSD ADF 3 . w x method on extended clusters XO Ba Ti embedded in a punctual charge set depicting 6 8 6 nq Ž .
3 q 4 q the crystalline environment. The transition ions X are Fe n s 2, 3, 4, 5 , Ti , Nb , and Nb 5q . Some related defects like FeᎏV , where V stands for a lacunar oxygen site, are o o also investigated through a similar process. The positions of impurity levels insides the O ᎏTi band gap are obtained from eigenvalues and related optical transition or 2 3 d p ionization energies are calculated using excited states. This allows us to discuss the photorefractive effect present in such doped materials. The EPR fine-structure parameters a and D are also derived for Fe 3q in cubic and tetragonal symmetries from crystal field calculations using parameters drawn from molecular orbital results.