Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures
The synthetic vanadinites (PbxCa10-x)(VO4)6F2δ, 1 < x < 9, adopt a P63/m apatite structure with 9.7590 (1) ≤ a ≤ 10.1179 (1) Å and 7.0434 (3) ≤ c ≤ 7.4021 (1) Å. The partitioning of calcium and lead over the AI(4f) and AII(6h) positions is nonstoichiometric with l...
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
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2011
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| Online Access: | https://hdl.handle.net/10356/79930 http://hdl.handle.net/10220/6900 |
| _version_ | 1824454959997911040 |
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| author | Dong, Zhili White, Timothy John |
| author2 | School of Materials Science & Engineering |
| author_facet | School of Materials Science & Engineering Dong, Zhili White, Timothy John |
| author_sort | Dong, Zhili |
| collection | NTU |
| description | The synthetic vanadinites (PbxCa10-x)(VO4)6F2δ, 1 < x < 9,
adopt a P63/m apatite structure with 9.7590 (1) ≤ a ≤ 10.1179 (1) Å and 7.0434 (3) ≤ c ≤ 7.4021 (1) Å. The
partitioning of calcium and lead over the AI(4f) and AII(6h) positions is nonstoichiometric with lead preferentially
entering the larger AII site. High-resolution electron microscopy
showed that samples annealed for 10 h at 1073 K are in
disequilibrium with calcium- and lead-rich microdomains coexisting
at unit-cell scales. For (Pb5Ca5)(VO4)6F2δ, sintering in
excess of 2 weeks is required for the metals to order
macroscopically. As annealing progresses, c/a, the partitioning
coefficient kPb(AI/AII) and the AIO6 metaprism twist angle (φ)
adjust ooperatively to enlarge the apatite channel, and
thereby accommodate higher lead content. These results
demonstrate that φ is a sensitive measure of disequilibrium
and a useful device for monitoring changes in apatite topology
as a function of composition. |
| first_indexed | 2025-02-19T03:30:36Z |
| format | Journal Article |
| id | ntu-10356/79930 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:30:36Z |
| publishDate | 2011 |
| record_format | dspace |
| spelling | ntu-10356/799302023-07-14T15:49:31Z Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures Dong, Zhili White, Timothy John School of Materials Science & Engineering DRNTU::Engineering::Materials::Ecomaterials The synthetic vanadinites (PbxCa10-x)(VO4)6F2δ, 1 < x < 9, adopt a P63/m apatite structure with 9.7590 (1) ≤ a ≤ 10.1179 (1) Å and 7.0434 (3) ≤ c ≤ 7.4021 (1) Å. The partitioning of calcium and lead over the AI(4f) and AII(6h) positions is nonstoichiometric with lead preferentially entering the larger AII site. High-resolution electron microscopy showed that samples annealed for 10 h at 1073 K are in disequilibrium with calcium- and lead-rich microdomains coexisting at unit-cell scales. For (Pb5Ca5)(VO4)6F2δ, sintering in excess of 2 weeks is required for the metals to order macroscopically. As annealing progresses, c/a, the partitioning coefficient kPb(AI/AII) and the AIO6 metaprism twist angle (φ) adjust ooperatively to enlarge the apatite channel, and thereby accommodate higher lead content. These results demonstrate that φ is a sensitive measure of disequilibrium and a useful device for monitoring changes in apatite topology as a function of composition. Published version 2011-07-14T01:51:00Z 2019-12-06T13:37:04Z 2011-07-14T01:51:00Z 2019-12-06T13:37:04Z 2004 2004 Journal Article Dong, Z., & White, T. J. (2004). Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures. Acta Crystallographica B, 60, 138-145. https://hdl.handle.net/10356/79930 http://hdl.handle.net/10220/6900 10.1107/S0108768104001831 en Acta crystallographica B © 2004 International Union of Crystallography. This paper was published in Acta Crystallographica B and is made available as an electronic reprint (preprint) with permission of International Union of Crystallography. The paper can be found at the following DOI: http://dx.doi.org/10.1107/S0108768104001831. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law. 8 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Materials::Ecomaterials Dong, Zhili White, Timothy John Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures |
| title | Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures |
| title_full | Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures |
| title_fullStr | Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures |
| title_full_unstemmed | Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures |
| title_short | Calcium-lead fluoro-vanadinite apatites. I. Disequilibrium structures |
| title_sort | calcium lead fluoro vanadinite apatites i disequilibrium structures |
| topic | DRNTU::Engineering::Materials::Ecomaterials |
| url | https://hdl.handle.net/10356/79930 http://hdl.handle.net/10220/6900 |
| work_keys_str_mv | AT dongzhili calciumleadfluorovanadiniteapatitesidisequilibriumstructures AT whitetimothyjohn calciumleadfluorovanadiniteapatitesidisequilibriumstructures |