First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions
Density Functional Theory applying the generalised gradient approximation is used to study the phase stability of (AlxCr1−x)2O3 solid solutions in the context of physical vapour deposition (PVD). Our results show that the energy of formation for the hexagonal α phase is lower than for the metastable...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2016-02-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/1.4941573 |
| _version_ | 1818149807072477184 |
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| author | C. M. Koller N. Koutná J. Ramm S. Kolozsvári J. Paulitsch D. Holec P. H. Mayrhofer |
| author_facet | C. M. Koller N. Koutná J. Ramm S. Kolozsvári J. Paulitsch D. Holec P. H. Mayrhofer |
| author_sort | C. M. Koller |
| collection | DOAJ |
| description | Density Functional Theory applying the generalised gradient approximation is used to study the phase stability of (AlxCr1−x)2O3 solid solutions in the context of physical vapour deposition (PVD). Our results show that the energy of formation for the hexagonal α phase is lower than for the metastable cubic γ and B1-like phases–independent of the Al content x. Even though this suggests higher stability of the α phase, its synthesis by physical vapour deposition is difficult for temperatures below 800 °C. Aluminium oxide and Al-rich oxides typically exhibit a multi-phased, cubic-dominated structure. Using a model system of (Al0.69Cr0.31)2O3 which experimentally yields larger fractions of the desired hexagonal α phase, we show that point defects strongly influence the energetic relationships. Since defects and in particular point defects, are unavoidably present in PVD coatings, they are important factors and can strongly influence the stability regions. We explicitly show that defects with low formation energies (e.g. metal Frenkel pairs) are strongly preferred in the cubic phases, hence a reasonable factor contributing to the observed thermodynamically anomalous phase composition. |
| first_indexed | 2024-12-11T13:12:54Z |
| format | Article |
| id | doaj.art-60b6b426b68646bb81682032e1578c0d |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-12-11T13:12:54Z |
| publishDate | 2016-02-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-60b6b426b68646bb81682032e1578c0d2022-12-22T01:06:08ZengAIP Publishing LLCAIP Advances2158-32262016-02-0162025002025002-910.1063/1.4941573005602ADVFirst principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutionsC. M. Koller0N. Koutná1J. Ramm2S. Kolozsvári3J. Paulitsch4D. Holec5P. H. Mayrhofer6Christian Doppler Laboratory for Application Oriented Coating Development, TU Wien, Vienna, 1060, AustriaFaculty of Science, Masaryk University, Kotlářská 2, Brno, 61137, Czech RepublicOerlikon Balzers, Oerlikon Surface Solutions AG, Balzers, 9496, LiechtensteinPlansee Composite Materials GmbH, Lechbruck am See, 86983, GermanyChristian Doppler Laboratory for Application Oriented Coating Development, TU Wien, Vienna, 1060, AustriaChristian Doppler Laboratory for Application Oriented Coating Development, TU Wien, Vienna, 1060, AustriaChristian Doppler Laboratory for Application Oriented Coating Development, TU Wien, Vienna, 1060, AustriaDensity Functional Theory applying the generalised gradient approximation is used to study the phase stability of (AlxCr1−x)2O3 solid solutions in the context of physical vapour deposition (PVD). Our results show that the energy of formation for the hexagonal α phase is lower than for the metastable cubic γ and B1-like phases–independent of the Al content x. Even though this suggests higher stability of the α phase, its synthesis by physical vapour deposition is difficult for temperatures below 800 °C. Aluminium oxide and Al-rich oxides typically exhibit a multi-phased, cubic-dominated structure. Using a model system of (Al0.69Cr0.31)2O3 which experimentally yields larger fractions of the desired hexagonal α phase, we show that point defects strongly influence the energetic relationships. Since defects and in particular point defects, are unavoidably present in PVD coatings, they are important factors and can strongly influence the stability regions. We explicitly show that defects with low formation energies (e.g. metal Frenkel pairs) are strongly preferred in the cubic phases, hence a reasonable factor contributing to the observed thermodynamically anomalous phase composition.http://dx.doi.org/10.1063/1.4941573 |
| spellingShingle | C. M. Koller N. Koutná J. Ramm S. Kolozsvári J. Paulitsch D. Holec P. H. Mayrhofer First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions AIP Advances |
| title | First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions |
| title_full | First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions |
| title_fullStr | First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions |
| title_full_unstemmed | First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions |
| title_short | First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions |
| title_sort | first principles studies on the impact of point defects on the phase stability of alxcr1 x 2o3 solid solutions |
| url | http://dx.doi.org/10.1063/1.4941573 |
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