Quantum-chemical study of excitons in tetragonal BaTiO3 and SrTiO3 crystals

Ricardo Viteri; Luis Miguel Procel; Francisco Tipan; Diego Fernando Ortiz; Arvids Stashans

doi:10.1117/12.515664

8 August 2003 Quantum-chemical study of excitons in tetragobnal BaTiO₃ and SrTiO₃ crystals

Ricardo Viteri, Luis Miguel Procel, Francisco Tipan, Diego Fernando Ortiz, Arvids Stashans

Proceedings Volume 5122, Advanced Organic and Inorganic Optical Materials; (2003) https://doi.org/10.1117/12.515664
Event: 2003 Chapter books, 2003, Bellingham, WA, United States

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.

Citation Download Citation

Ricardo Viteri, Luis Miguel Procel, Francisco Tipan, Diego Fernando Ortiz, and Arvids Stashans "Quantum-chemical study of excitons in tetragobnal BaTiO₃ and SrTiO₃ crystals", Proc. SPIE 5122, Advanced Organic and Inorganic Optical Materials, (8 August 2003); https://doi.org/10.1117/12.515664

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