Structural derivation and crystal chemistry of apatites

T. J. White; Dong ZhiLi

doi:10.1107/S0108768102019894

Structural derivation and crystal chemistry of apatites

T. J. White^*, Dong ZhiLi

^*Corresponding author for this work

Nanyang Technological University

Research output: Contribution to journal › Article › peer-review

310 Citations (Scopus)

Abstract

The crystal structures of the [A(1) ₂][A(2) ₃](BO ₄) ₃X apatites and the related compounds [A-(1) ₂][A(2) ₃](BO ₅) ₃X and [A(1) ₂][A(2) ₃](BO ₃) ₃X are collated and reviewed. The structural aristotype for this family is Mn ₅Si ₃ (D8 ₈ type, P6 ₃/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 space-groups leads to three apatite families whose high-symmetry members are P6 ₃/m, Cmcm and P6 ₃cm. 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 φ projected on (001) of the A(1)O ₆ metaprism. For apatites that contain the same A cation, it is shown that φ decreases linearly as a function of increasing average ionic radius of the formula unit. Large deviations from this simple relationship may indicate departures from P6 ₃/m symmetry or cation ordering. The inclusion of A(1)O ₆ metaprisms in structure drawings is useful for comparing apatites and condensed-apatites such as Sr ₅(BO ₃) ₃Br. The most common symmetry for the 74 chemically distinct [A(1) ₂][A(2) ₃]-(BO ₄) ₃X apatites that were surveyed was P6 ₃/m (57%), with progressively more complex chemistries adopting P6 ₃ (21%), P3̄ (9%), P6̄ (4.3%), P2-/m (4.3%) and P2 ₁ (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 BO ₅ square pyramidal units (as in ReO ₅) or BO ₃ triangular coordination (as in AsO ₃). Polysomatism arises through the ordered filling of [001] BO ₄ tetrahedral strings to generate the apatite-nasonite family of structures.

Original language	English
Pages (from-to)	1-16
Number of pages	16
Journal	Acta Crystallographica Section B: Structural Science
Volume	59
Issue number	1
DOIs	https://doi.org/10.1107/S0108768102019894
Publication status	Published - Feb 2003
Externally published	Yes

ASJC Scopus Subject Areas

General Biochemistry,Genetics and Molecular Biology

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title = "Structural derivation and crystal chemistry of apatites",

abstract = "The crystal structures of the [A(1) 2][A(2) 3](BO 4) 3X apatites and the related compounds [A-(1) 2][A(2) 3](BO 5) 3X and [A(1) 2][A(2) 3](BO 3) 3X are collated and reviewed. The structural aristotype for this family is Mn 5Si 3 (D8 8 type, P6 3/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 space-groups leads to three apatite families whose high-symmetry members are P6 3/m, Cmcm and P6 3cm. 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 φ projected on (001) of the A(1)O 6 metaprism. For apatites that contain the same A cation, it is shown that φ decreases linearly as a function of increasing average ionic radius of the formula unit. Large deviations from this simple relationship may indicate departures from P6 3/m symmetry or cation ordering. The inclusion of A(1)O 6 metaprisms in structure drawings is useful for comparing apatites and condensed-apatites such as Sr 5(BO 3) 3Br. The most common symmetry for the 74 chemically distinct [A(1) 2][A(2) 3]-(BO 4) 3X apatites that were surveyed was P6 3/m (57\%), with progressively more complex chemistries adopting P6 3 (21\%), P{\=3} (9\%), P{\=6} (4.3\%), P2-/m (4.3\%) and P2 1 (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 BO 5 square pyramidal units (as in ReO 5) or BO 3 triangular coordination (as in AsO 3). Polysomatism arises through the ordered filling of [001] BO 4 tetrahedral strings to generate the apatite-nasonite family of structures.",

author = "White, \{T. J.\} and Dong ZhiLi",

year = "2003",

month = feb,

doi = "10.1107/S0108768102019894",

language = "English",

volume = "59",

pages = "1--16",

journal = "Acta Crystallographica Section B: Structural Science",

issn = "0108-7681",

publisher = "International Union of Crystallography",

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}

TY - JOUR

T1 - Structural derivation and crystal chemistry of apatites

AU - White, T. J.

AU - ZhiLi, Dong

PY - 2003/2

Y1 - 2003/2

N2 - The crystal structures of the [A(1) 2][A(2) 3](BO 4) 3X apatites and the related compounds [A-(1) 2][A(2) 3](BO 5) 3X and [A(1) 2][A(2) 3](BO 3) 3X are collated and reviewed. The structural aristotype for this family is Mn 5Si 3 (D8 8 type, P6 3/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 space-groups leads to three apatite families whose high-symmetry members are P6 3/m, Cmcm and P6 3cm. 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 φ projected on (001) of the A(1)O 6 metaprism. For apatites that contain the same A cation, it is shown that φ decreases linearly as a function of increasing average ionic radius of the formula unit. Large deviations from this simple relationship may indicate departures from P6 3/m symmetry or cation ordering. The inclusion of A(1)O 6 metaprisms in structure drawings is useful for comparing apatites and condensed-apatites such as Sr 5(BO 3) 3Br. The most common symmetry for the 74 chemically distinct [A(1) 2][A(2) 3]-(BO 4) 3X apatites that were surveyed was P6 3/m (57%), with progressively more complex chemistries adopting P6 3 (21%), P3̄ (9%), P6̄ (4.3%), P2-/m (4.3%) and P2 1 (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 BO 5 square pyramidal units (as in ReO 5) or BO 3 triangular coordination (as in AsO 3). Polysomatism arises through the ordered filling of [001] BO 4 tetrahedral strings to generate the apatite-nasonite family of structures.

AB - The crystal structures of the [A(1) 2][A(2) 3](BO 4) 3X apatites and the related compounds [A-(1) 2][A(2) 3](BO 5) 3X and [A(1) 2][A(2) 3](BO 3) 3X are collated and reviewed. The structural aristotype for this family is Mn 5Si 3 (D8 8 type, P6 3/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 space-groups leads to three apatite families whose high-symmetry members are P6 3/m, Cmcm and P6 3cm. 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 φ projected on (001) of the A(1)O 6 metaprism. For apatites that contain the same A cation, it is shown that φ decreases linearly as a function of increasing average ionic radius of the formula unit. Large deviations from this simple relationship may indicate departures from P6 3/m symmetry or cation ordering. The inclusion of A(1)O 6 metaprisms in structure drawings is useful for comparing apatites and condensed-apatites such as Sr 5(BO 3) 3Br. The most common symmetry for the 74 chemically distinct [A(1) 2][A(2) 3]-(BO 4) 3X apatites that were surveyed was P6 3/m (57%), with progressively more complex chemistries adopting P6 3 (21%), P3̄ (9%), P6̄ (4.3%), P2-/m (4.3%) and P2 1 (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 BO 5 square pyramidal units (as in ReO 5) or BO 3 triangular coordination (as in AsO 3). Polysomatism arises through the ordered filling of [001] BO 4 tetrahedral strings to generate the apatite-nasonite family of structures.

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Structural derivation and crystal chemistry of apatites

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