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RESEARCH PRODUCT
Theoretical simulations of the radiation-induced defect processes in insulating materials
Eugene A. KotominPatrick W. M. Jacobssubject
Nuclear and High Energy PhysicsChemistryCorundumActivation energyElectronic structureengineering.materialAlkali metalPolaronDiatomic moleculeCovalent bondengineeringAtomic physicsAbsorption (electromagnetic radiation)Instrumentationdescription
Abstract The results of two basic kinds of computer simulations of radiation-induced processes in insulating materials, one based on quantum-mechanical and pair-potential (atomistic) approaches, and the other a phenomenological theory of diffusion-controlled reactions, are presented. It is shown that, by combining different techniques (atom-atom potentials and semi-empirical quantum chemical methods) the optimized geometry and the electronic structure of a family of hole centres in crystalline corundum (α-Al2O3) could be found. Their energetics are analyzed; V2−, V−V−Mg hole centres all have a common basic element, namely the diatomic molecule O23−, which is responsible for their similar absorption energies. Our calculations provide evidence for the existence of a small-radius two-centre polaron (self-trapped hole, or STH) with an optical absorption energy of around 2.9 eV. The strong covalent bonding of the two O atoms sharing a hole makes this centre analogous to the VK centre in alkali halides. The calculated activation energy for the STH hops (≈ 0.9 eV) between different O triangles is close to the experimental.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1994-06-01 | Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms |