Point defects and their effect on dielectric permittivity in strontium titanate ceramics
| Autor: | Adriana Peleš-Tadić, Vladimir A. Blagojević, Jelena Vujančević, Darko Kosanović, Jelena Živojinović |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
chemistry.chemical_element Physics::Optics Dielectric lattice distortion TP1-1185 DFT calculations dft calculations Tetragonal crystal system chemistry.chemical_compound Condensed Matter::Materials Science Distortion Materials Chemistry Physics::Atomic and Molecular Clusters point defects Ceramic strontium titanate Condensed matter physics Chemical technology Metals and Alloys Condensed Matter Physics Crystallographic defect Lattice (module) chemistry dielectric properties visual_art Ceramics and Composites Strontium titanate visual_art.visual_art_medium Titanium |
| Zdroj: | Science of Sintering, Vol 53, Iss 3, Pp 285-299 (2021) Science of Sintering |
| ISSN: | 1820-7413 |
| Popis: | The origin of dielectric properties of strontium titanate ceramics is investigated using DFT calculations in periodic system. It was determined that the main factors contributing to the increase in dielectric permittivity are: tetragonal distortion of the normally cubic lattice, and charge imbalance induced displacement of titanium center from its central position. Oxygen vacancies were determined to create significantly larger effects than other types of vacancies, like Ti and SrO. The extent of tetragonal distortion was found to be determined by oxygen vacancy distribution, rather than total concentration: relatively symmetrical distribution of oxygen vacancies resulted in smaller tetragonal distortion of the lattice, and, consequently, smaller increase in dielectric permittivity. Charge imbalance naturally destabilizes the cubic lattice, forcing the Ti-atom out of its central position, resulting in tetragonal lattice with increased dielectric permittivity. The process stabilizes the strontium titanate lattice, while increasing the c/a ratio. Therefore, the dielectric permittivity of strontium titanate can be increased by changes to the system that increase tetragonal distortion of the lattice and/or introduce additional negative charge. |
| Databáze: | OpenAIRE |
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