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Proceedings Paper

Quantum-chemical study of excitons in tetragonal BaTiO3 and SrTiO3 crystals
Author(s): Ricardo Viteri; Luis Miguel Procel; Francisco Tipan; Diego Fernando Ortiz; Arvids Stashans
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Paper Abstract

Using a quantum-chemical INDO method based on the Hartree-Fock formalism and the periodic large unit cell (LUC) model we present a theoretical interpretation of the structural and electronic properties of triplet excitons in the tetragonal BaTiO3 and SrTiO3 crystals. Our study demonstrates that the exciton structure has particularities in each material. In the BaTiO3 the defect structure corresponds to the so-called Mott-Wannier-type exciton having a considerable separation, 7.0 Å, between the hole and the electron. Meanwhile, in SrTiO3 the structural and electronic features of the triplet exciton are quite different. The hole-electron distance is about 2.14 Å and the defect is well localized in two contiguous atoms: the hole on one of the O atoms and the electron on the neighbor Ti atom. The calculated luminescence energy using the so-called ΔSCF method is found to be equal to 0.94 eV and 1.13 eV for BaTiO3 and SrTiO3, respectively. Since it falls within the infrared part of the spectrum, the experimentally detected green luminescence due to photo-excited states should be attributed to the singlet excitons.

Paper Details

Date Published: 8 August 2003
PDF: 8 pages
Proc. SPIE 5122, Advanced Organic and Inorganic Optical Materials, (8 August 2003);
Show Author Affiliations
Ricardo Viteri, Corp. de Fisica Fundamental y Aplicada (Ecuador)
Luis Miguel Procel, Corp. de Fisica Fundamental y Aplicada (Ecuador)
Francisco Tipan, Univ. San Francisco de Quito (Ecuador)
Diego Fernando Ortiz, Corp. de Fisica Fundamental y Aplicada (Ecuador)
Arvids Stashans, Corp. de Fisica Fundamental y Aplicada (Ecuador)

Published in SPIE Proceedings Vol. 5122:
Advanced Organic and Inorganic Optical Materials
Andris Krumins; Donats Millers; Inta Muzikante; Andris Sternbergs; Vismants Zauls, Editor(s)

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