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| Main Authors: | , , , , |
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| Format: | Preprint |
| Published: |
2019
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/1902.08948 |
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| _version_ | 1866929485081739264 |
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| author | Seknazi, E. Levy, D. Polishchuk, I. Katsman, A. Pokroy, Prof B. |
| author_facet | Seknazi, E. Levy, D. Polishchuk, I. Katsman, A. Pokroy, Prof B. |
| contents | Calcite has the ability to host large amounts of intracrystalline inclusions, a phenomenon that is known to be the case in biominerals and has been demonstrated in bio-inspired synthetic systems. In this study, we focused on barium as the inclusion. Highly substituted Ba-calcite possesses disordered carbonate orientations, characteristic of R-3m symmetry. We show that calcite undergoes an ordered-disordered transition, in which the carbonate groups undergo progressive loss of their rotational order with increasing amounts of incorporated Ba, and reach complete rotational disorder for a critical amount of Ba. We characterize this transition and propose a theoretical model justifying the influence of Ba. Moreover, the disordered R-3m Ba-substituted calcite has been previously identified as a high-temperature phase or as a highly metastable room-temperature phase. We challenge those descriptions by successfully synthesizing it under slow-rate conditions and by studying its thermal behavior, and we conclude that the fully disordered Ba-calcite is stable, whereas the transitional, partially disordered Ba-calcite phase is metastable. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_1902_08948 |
| institution | arXiv |
| publishDate | 2019 |
| record_format | arxiv |
| spellingShingle | Formation and Stability of Ordered and Disordered Ba-substituted Calcite Phases Seknazi, E. Levy, D. Polishchuk, I. Katsman, A. Pokroy, Prof B. Materials Science Calcite has the ability to host large amounts of intracrystalline inclusions, a phenomenon that is known to be the case in biominerals and has been demonstrated in bio-inspired synthetic systems. In this study, we focused on barium as the inclusion. Highly substituted Ba-calcite possesses disordered carbonate orientations, characteristic of R-3m symmetry. We show that calcite undergoes an ordered-disordered transition, in which the carbonate groups undergo progressive loss of their rotational order with increasing amounts of incorporated Ba, and reach complete rotational disorder for a critical amount of Ba. We characterize this transition and propose a theoretical model justifying the influence of Ba. Moreover, the disordered R-3m Ba-substituted calcite has been previously identified as a high-temperature phase or as a highly metastable room-temperature phase. We challenge those descriptions by successfully synthesizing it under slow-rate conditions and by studying its thermal behavior, and we conclude that the fully disordered Ba-calcite is stable, whereas the transitional, partially disordered Ba-calcite phase is metastable. |
| title | Formation and Stability of Ordered and Disordered Ba-substituted Calcite Phases |
| topic | Materials Science |
| url | https://arxiv.org/abs/1902.08948 |