Structural derivation and crystal chemistry of apatites
The crystal structures of the [A(1)2][A(2)3](BO4)3X apatites and the related compounds [A(1)2][A(2)3](BO5)3X and [A(1)2][A(2)3](BO3)3X are collated and reviewed. The structural aristotype for this family is Mn5Si3 (D88 type, P63/mcm symmetr...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2011
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| Online Access: | https://hdl.handle.net/10356/90582 http://hdl.handle.net/10220/6899 |
| _version_ | 1824455833490030592 |
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| author | White, Timothy John Dong, Zhili |
| author2 | School of Materials Science & Engineering |
| author_facet | School of Materials Science & Engineering White, Timothy John Dong, Zhili |
| author_sort | White, Timothy John |
| collection | NTU |
| description | The crystal structures of the [A(1)2][A(2)3](BO4)3X apatites
and the related compounds [A(1)2][A(2)3](BO5)3X and
[A(1)2][A(2)3](BO3)3X are collated and reviewed. The
structural aristotype for this family is Mn5Si3 (D88 type,
P63/mcm symmetry), whose cation array approximates that of
all derivatives and from which related structures arise through
the systematic insertion of anions into tetrahedral, triangular
or linear interstices. The construction of a hierarchy of spacegroups
leads to three apatite families whose high-symmetry
members are P63/m, Cmcm and P63cm. Alternatively,
systematic crystallographic changes in apatite solid-solution
series may be practically described as deviations from regular
anion nets, with particular focus on the O(1)-A(1)-O(2)
twist angle ' projected on (001) of the A(1)O6 metaprism. For
apatites that contain the same A cation, it is shown that '
decreases linearly as a function of increasing average ionic
radius of the formula unit. Large deviations from this simple
relationship may indicate departures from P63/m symmetry or
cation ordering. The inclusion of A(1)O6 metaprisms in
structure drawings is useful for comparing apatites and
condensed-apatites such as Sr5(BO3)3Br. The most common
symmetry for the 74 chemically distinct [A(1)2][A(2)3]-
(BO4)3X apatites that were surveyed was P63/m (57%), with
progressively more complex chemistries adopting P63 (21%),
P 3 (9%), P 6 (4.3%), P21/m (4.3%) and P21 (4.3%). In
chemically complex apatites, charge balance is usually
maintained through charge-coupled cation substitutions, or
through appropriate mixing of monovalent and divalent X
anions or X-site vacancies. More rarely, charge compensation
is achieved through insertion/removal of oxygen to produce
BO5 square pyramidal units (as in ReO5) or BO3 triangular
coordination (as in AsO3). Polysomatism arises through the
ordered filling of [001] BO4 tetrahedral strings to generate the
apatite±nasonite family of structures. |
| first_indexed | 2025-02-19T03:44:29Z |
| format | Journal Article |
| id | ntu-10356/90582 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:44:29Z |
| publishDate | 2011 |
| record_format | dspace |
| spelling | ntu-10356/905822023-07-14T15:46:44Z Structural derivation and crystal chemistry of apatites White, Timothy John Dong, Zhili School of Materials Science & Engineering DRNTU::Engineering::Materials::Ecomaterials The crystal structures of the [A(1)2][A(2)3](BO4)3X apatites and the related compounds [A(1)2][A(2)3](BO5)3X and [A(1)2][A(2)3](BO3)3X are collated and reviewed. The structural aristotype for this family is Mn5Si3 (D88 type, P63/mcm symmetry), whose cation array approximates that of all derivatives and from which related structures arise through the systematic insertion of anions into tetrahedral, triangular or linear interstices. The construction of a hierarchy of spacegroups leads to three apatite families whose high-symmetry members are P63/m, Cmcm and P63cm. Alternatively, systematic crystallographic changes in apatite solid-solution series may be practically described as deviations from regular anion nets, with particular focus on the O(1)-A(1)-O(2) twist angle ' projected on (001) of the A(1)O6 metaprism. For apatites that contain the same A cation, it is shown that ' decreases linearly as a function of increasing average ionic radius of the formula unit. Large deviations from this simple relationship may indicate departures from P63/m symmetry or cation ordering. The inclusion of A(1)O6 metaprisms in structure drawings is useful for comparing apatites and condensed-apatites such as Sr5(BO3)3Br. The most common symmetry for the 74 chemically distinct [A(1)2][A(2)3]- (BO4)3X apatites that were surveyed was P63/m (57%), with progressively more complex chemistries adopting P63 (21%), P 3 (9%), P 6 (4.3%), P21/m (4.3%) and P21 (4.3%). In chemically complex apatites, charge balance is usually maintained through charge-coupled cation substitutions, or through appropriate mixing of monovalent and divalent X anions or X-site vacancies. More rarely, charge compensation is achieved through insertion/removal of oxygen to produce BO5 square pyramidal units (as in ReO5) or BO3 triangular coordination (as in AsO3). Polysomatism arises through the ordered filling of [001] BO4 tetrahedral strings to generate the apatite±nasonite family of structures. Published version 2011-07-14T01:35:41Z 2019-12-06T17:50:17Z 2011-07-14T01:35:41Z 2019-12-06T17:50:17Z 2003 2003 Journal Article White, T. J., & Dong, Z. L. (2003). Structural derivation and crystal chemistry of apatite. Acta Crystallographica B, 59(1), 1-16. https://hdl.handle.net/10356/90582 http://hdl.handle.net/10220/6899 10.1107/S0108768102019894 en Acta crystallographica B © 2003 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/S0108768102019894. 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. 16 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Materials::Ecomaterials White, Timothy John Dong, Zhili Structural derivation and crystal chemistry of apatites |
| title | Structural derivation and crystal chemistry of apatites |
| title_full | Structural derivation and crystal chemistry of apatites |
| title_fullStr | Structural derivation and crystal chemistry of apatites |
| title_full_unstemmed | Structural derivation and crystal chemistry of apatites |
| title_short | Structural derivation and crystal chemistry of apatites |
| title_sort | structural derivation and crystal chemistry of apatites |
| topic | DRNTU::Engineering::Materials::Ecomaterials |
| url | https://hdl.handle.net/10356/90582 http://hdl.handle.net/10220/6899 |
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