Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8)
The room temperature crystal structures of three compositions in the system BaIr(1-x)Co(x)O(3-δ) (x = 0.5, 0.7, 0.8) have been determined from X-ray and neutron powder diffraction data. BaIr0.5Co0.5O(3.02(1)), BaIr0.3Co0.7O(2.84(1)), and BaIr0.2Co0.8O(2.83(1)) adopt 12R, 10H, and 5H perovskite struc...
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| Format: | Journal article |
| Language: | English |
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2000
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| _version_ | 1797089108624932864 |
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| author | Vente, J Battle, P |
| author_facet | Vente, J Battle, P |
| author_sort | Vente, J |
| collection | OXFORD |
| description | The room temperature crystal structures of three compositions in the system BaIr(1-x)Co(x)O(3-δ) (x = 0.5, 0.7, 0.8) have been determined from X-ray and neutron powder diffraction data. BaIr0.5Co0.5O(3.02(1)), BaIr0.3Co0.7O(2.84(1)), and BaIr0.2Co0.8O(2.83(1)) adopt 12R, 10H, and 5H perovskite structures, respectively; the distribution of Co and Ir cations over corner-sharing and face-sharing sites has been determined, and the Co/Ir-O bond lengths have been used to assign the cation oxidation states as Ir5+ and Co3+/Co4+. Arguments based on bond lengths and magnetic susceptibility data have been used to assign spin states; at room temperature BaIr0.5Co0.5O(3-δ) contains both high-spin and low-spin Co3+. The distribution of anion vacancies has been determined for x = 0.7, 0.8; in the latter case there is evidence for the replacement of some BaO3 layers in the pseudo-hcp structure by BaO2 layers, thus introducing tetrahedral transition metal sites which are found to be occupied by Co. Neutron diffraction experiments carried out at 5 K revealed a monoclinic distortion in the x = 0.5 sample, with the environment of the high-spin Co3+ cation undergoing a Jahn-Teller distortion. The structures of the x = 0.7, 0.8 phases did not change significantly on cooling. Measurements of magnetization as a function of applied field suggest that spin glass or cluster glass behavior is present in x = 0.5, 0.7 below 50 K. In the case of x = 0.8, magnetization and neutron diffraction data suggest the formation of a weak ferromagnet with a saturation magnetization of 0.60 μ(B) per Co cation at 5 K. (C) 2000 Academic Press. |
| first_indexed | 2024-03-07T02:59:45Z |
| format | Journal article |
| id | oxford-uuid:b08dcd81-5189-44bb-b368-44903877bb9a |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T02:59:45Z |
| publishDate | 2000 |
| record_format | dspace |
| spelling | oxford-uuid:b08dcd81-5189-44bb-b368-44903877bb9a2022-03-27T03:57:20ZStructural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8)Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b08dcd81-5189-44bb-b368-44903877bb9aEnglishSymplectic Elements at Oxford2000Vente, JBattle, PThe room temperature crystal structures of three compositions in the system BaIr(1-x)Co(x)O(3-δ) (x = 0.5, 0.7, 0.8) have been determined from X-ray and neutron powder diffraction data. BaIr0.5Co0.5O(3.02(1)), BaIr0.3Co0.7O(2.84(1)), and BaIr0.2Co0.8O(2.83(1)) adopt 12R, 10H, and 5H perovskite structures, respectively; the distribution of Co and Ir cations over corner-sharing and face-sharing sites has been determined, and the Co/Ir-O bond lengths have been used to assign the cation oxidation states as Ir5+ and Co3+/Co4+. Arguments based on bond lengths and magnetic susceptibility data have been used to assign spin states; at room temperature BaIr0.5Co0.5O(3-δ) contains both high-spin and low-spin Co3+. The distribution of anion vacancies has been determined for x = 0.7, 0.8; in the latter case there is evidence for the replacement of some BaO3 layers in the pseudo-hcp structure by BaO2 layers, thus introducing tetrahedral transition metal sites which are found to be occupied by Co. Neutron diffraction experiments carried out at 5 K revealed a monoclinic distortion in the x = 0.5 sample, with the environment of the high-spin Co3+ cation undergoing a Jahn-Teller distortion. The structures of the x = 0.7, 0.8 phases did not change significantly on cooling. Measurements of magnetization as a function of applied field suggest that spin glass or cluster glass behavior is present in x = 0.5, 0.7 below 50 K. In the case of x = 0.8, magnetization and neutron diffraction data suggest the formation of a weak ferromagnet with a saturation magnetization of 0.60 μ(B) per Co cation at 5 K. (C) 2000 Academic Press. |
| spellingShingle | Vente, J Battle, P Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8) |
| title | Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8) |
| title_full | Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8) |
| title_fullStr | Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8) |
| title_full_unstemmed | Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8) |
| title_short | Structural Chemistry and Electronic Properties of the hexagonal perovskites BaIr1-xCoxO3-delta (x = 0.5, 0.7, 0.8) |
| title_sort | structural chemistry and electronic properties of the hexagonal perovskites bair1 xcoxo3 delta x 0 5 0 7 0 8 |
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