Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films
Subtle changes in the atomic arrangement of NiTiO<sub>3</sub> in the ilmenite structure affects its symmetry and properties. At high temperatures, the cations are randomly distributed throughout the structure, resulting in the corundum structure with <i>R</i>−3<i...
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2019-12-01
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| Online Access: | https://www.mdpi.com/1996-1944/13/1/112 |
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| author | Jon Einar Bratvold Helmer Fjellvåg Ola Nilsen |
| author_facet | Jon Einar Bratvold Helmer Fjellvåg Ola Nilsen |
| author_sort | Jon Einar Bratvold |
| collection | DOAJ |
| description | Subtle changes in the atomic arrangement of NiTiO<sub>3</sub> in the ilmenite structure affects its symmetry and properties. At high temperatures, the cations are randomly distributed throughout the structure, resulting in the corundum structure with <i>R</i>−3<i>c</i> symmetry. Upon cooling, the cations order in alternating layers along the crystallographic <i>c</i> axis, resulting in the ilmenite structure with <i>R</i>−3 symmetry. Related to this is the <i>R</i>3<i>c</i> symmetry, where the cations alternate both perpendicularly and along the <i>c</i> axis. NiTiO<sub>3</sub> with the latter structure is highly interesting as it exhibits ferroelectric properties. The close relationship between structure and properties for ilmenite-related structures emphasizes the importance of being able to control the symmetry during synthesis. We show that the orientation and symmetry of thin films of NiTiO<sub>3</sub> formed by atomic layer deposition (ALD) can be controlled by choice of substrate. The disordered phase (<i>R</i>−3<i>c</i>), previously only observed at elevated temperatures, have been deposited at 250 °C on α-Al<sub>2</sub>O<sub>3</sub> substrates, while post-deposition annealing at moderate temperatures (650 °C) induces ordering (<i>R</i>−3). We have in addition explored the symmetry and epitaxial orientation obtained when deposited on substrates of LaAlO<sub>3</sub>(100), SrTiO<sub>3</sub>(100) and MgO(100). The presented work demonstrates the possibilities of ALD to form metastable phases through choice of substrates. |
| first_indexed | 2024-04-12T07:06:54Z |
| format | Article |
| id | doaj.art-233b624c85614678ac61cc4d6615d585 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-04-12T07:06:54Z |
| publishDate | 2019-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-233b624c85614678ac61cc4d6615d5852022-12-22T03:42:45ZengMDPI AGMaterials1996-19442019-12-0113111210.3390/ma13010112ma13010112Phase and Orientation Control of NiTiO<sub>3</sub> Thin FilmsJon Einar Bratvold0Helmer Fjellvåg1Ola Nilsen2Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, NorwayCentre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, NorwayCentre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, NorwaySubtle changes in the atomic arrangement of NiTiO<sub>3</sub> in the ilmenite structure affects its symmetry and properties. At high temperatures, the cations are randomly distributed throughout the structure, resulting in the corundum structure with <i>R</i>−3<i>c</i> symmetry. Upon cooling, the cations order in alternating layers along the crystallographic <i>c</i> axis, resulting in the ilmenite structure with <i>R</i>−3 symmetry. Related to this is the <i>R</i>3<i>c</i> symmetry, where the cations alternate both perpendicularly and along the <i>c</i> axis. NiTiO<sub>3</sub> with the latter structure is highly interesting as it exhibits ferroelectric properties. The close relationship between structure and properties for ilmenite-related structures emphasizes the importance of being able to control the symmetry during synthesis. We show that the orientation and symmetry of thin films of NiTiO<sub>3</sub> formed by atomic layer deposition (ALD) can be controlled by choice of substrate. The disordered phase (<i>R</i>−3<i>c</i>), previously only observed at elevated temperatures, have been deposited at 250 °C on α-Al<sub>2</sub>O<sub>3</sub> substrates, while post-deposition annealing at moderate temperatures (650 °C) induces ordering (<i>R</i>−3). We have in addition explored the symmetry and epitaxial orientation obtained when deposited on substrates of LaAlO<sub>3</sub>(100), SrTiO<sub>3</sub>(100) and MgO(100). The presented work demonstrates the possibilities of ALD to form metastable phases through choice of substrates.https://www.mdpi.com/1996-1944/13/1/112metal oxide thin filmsatomic layer depositionaldcrystallographyepitaxynitio<sub>3</sub> |
| spellingShingle | Jon Einar Bratvold Helmer Fjellvåg Ola Nilsen Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films Materials metal oxide thin films atomic layer deposition ald crystallography epitaxy nitio<sub>3</sub> |
| title | Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films |
| title_full | Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films |
| title_fullStr | Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films |
| title_full_unstemmed | Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films |
| title_short | Phase and Orientation Control of NiTiO<sub>3</sub> Thin Films |
| title_sort | phase and orientation control of nitio sub 3 sub thin films |
| topic | metal oxide thin films atomic layer deposition ald crystallography epitaxy nitio<sub>3</sub> |
| url | https://www.mdpi.com/1996-1944/13/1/112 |
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