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RESEARCH PRODUCT
Charge distribution and optical properties of and F centres in crystals
Roberts I. EglitisEugene A. KotominEugene A. KotominAnatoly I. Popovsubject
Delocalized electronMaterials scienceVacancy defectIonic bondingCharge densityGeneral Materials ScienceOrthorhombic crystal systemAbsorption (chemistry)Atomic physicsCondensed Matter PhysicsGround statePerovskite (structure)description
Results of quantum chemical calculations for the and F centres in cubic and orthorhombic phases of a perovskite ferroelectric are presented and analysed in the light of existing experimental literature. It is shown that one (two) electrons of the and F centres, respectively, are considerably delocalized, even in the ground state of defects, over the two Nb atoms nearest to the O vacancy, and other close atoms. They resemble more electron defects in partly covalent crystals (the so-called centre) than F-type centres in ionic MgO crystals. We predict two or three absorption bands (depending on the crystalline phase) for each of the defects. The calculated absorption energies for the centre are by 0.3 - 0.4 eV lower than those for the F centre.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1997-06-02 | Journal of Physics: Condensed Matter |