The crystal structure of the new mineral dyrnaesite-(La), Na8CeIVREE2(PO4)6

Tonci Balic Zunic

doi:10.1180/minmag.2016.080.096

The crystal structure of the new mineral dyrnaesite-(La), Na₈Ce^IVREE₂(PO₄)₆

3 Citationer (Scopus)

Abstract

Dyrnaesite-(La), Na_7.89(Ce_0.94Ca_0.06)_Σ1.00(La_1.14Ce_0.40Pr_0.10Nd_0.24Ca_0.12)_Σ2.00(PO₄)₆ is orthorhombic, Pnma, a = 18.4662(7), b = 16.0106(5), c = 7.0274(2) Å, V = 2077.7(1) Å³, Z = 4. The crystal structure is related to the group of Na₃REE(XO₄)₂ compounds (with X = P, V, As), based on the aphthitalite/glaserite
structural type. Dyrnaesite is distinct in having ordered Na vacancies, and a rare-earth element (REE) site occupied preferentially by Ce⁴⁺. This also distinguishes it from closely related vitusite-(Ce) [Na₃REE(PO₄)₂]. The relation of their unit cells is: a_d = b_v, b_d = 3a_v, c_d = 1/2c_v. The distinct Ce⁴⁺ site in dyrnaesite-(La) has smaller coordination with shorter bond lengths than the other REE site in the same structure or the REE sites in vitusite-(Ce). It is adjacent to the predominately vacant Na site, which in its turn has the largest coordination of all Na sites in the structure. REE sites, or Na sites in a [010] row (similar to [100] in vitusite-(Ce)) assume two types of coordinations with and without mirror symmetry and two different configurations of surrounding PO₄ tetrahedra. This summarizes the topological difference to vitusite-(Ce) where the corresponding coordinations are similar in the same row and intermediate in character to the two types in dyrnaesite-(La).

Originalsprog	Engelsk
Tidsskrift	Mineralogical Magazine
Vol/bind	81
Udgave nummer	1
Sider (fra-til)	199-208
Antal sider	10
ISSN	0026-461X
DOI	https://doi.org/10.1180/minmag.2016.080.096
Status	Udgivet - feb. 2017

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Det Natur- og Biovidenskabelige Fakultet

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10.1180/minmag.2016.080.096

Citationsformater

@article{38a687e61ab8496ea525aef453ebe93a,

title = "The crystal structure of the new mineral dyrnaesite-(La), Na8CeIVREE2(PO4)6",

abstract = "Dyrnaesite-(La), Na7.89(Ce0.94Ca0.06)Σ1.00(La1.14Ce0.40Pr0.10Nd0.24Ca0.12)Σ2.00(PO4)6 is orthorhombic, Pnma, a = 18.4662(7), b = 16.0106(5), c = 7.0274(2) {\AA}, V = 2077.7(1) {\AA}3, Z = 4. The crystal structure is related to the group of Na3REE(XO4)2 compounds (with X = P, V, As), based on the aphthitalite/glaseritestructural type. Dyrnaesite is distinct in having ordered Na vacancies, and a rare-earth element (REE) site occupied preferentially by Ce4+. This also distinguishes it from closely related vitusite-(Ce) [Na3REE(PO4)2]. The relation of their unit cells is: ad = bv, bd = 3av, cd = 1/2cv. The distinct Ce4+ site in dyrnaesite-(La) has smaller coordination with shorter bond lengths than the other REE site in the same structure or the REE sites in vitusite-(Ce). It is adjacent to the predominately vacant Na site, which in its turn has the largest coordination of all Na sites in the structure. REE sites, or Na sites in a [010] row (similar to [100] in vitusite-(Ce)) assume two types of coordinations with and without mirror symmetry and two different configurations of surrounding PO4 tetrahedra. This summarizes the topological difference to vitusite-(Ce) where the corresponding coordinations are similar in the same row and intermediate in character to the two types in dyrnaesite-(La).",

keywords = "Faculty of Science",

author = "{Balic Zunic}, Tonci",

year = "2017",

month = feb,

doi = "10.1180/minmag.2016.080.096",

language = "English",

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journal = "Mineralogical Magazine",

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T1 - The crystal structure of the new mineral dyrnaesite-(La), Na8CeIVREE2(PO4)6

AU - Balic Zunic, Tonci

PY - 2017/2

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N2 - Dyrnaesite-(La), Na7.89(Ce0.94Ca0.06)Σ1.00(La1.14Ce0.40Pr0.10Nd0.24Ca0.12)Σ2.00(PO4)6 is orthorhombic, Pnma, a = 18.4662(7), b = 16.0106(5), c = 7.0274(2) Å, V = 2077.7(1) Å3, Z = 4. The crystal structure is related to the group of Na3REE(XO4)2 compounds (with X = P, V, As), based on the aphthitalite/glaseritestructural type. Dyrnaesite is distinct in having ordered Na vacancies, and a rare-earth element (REE) site occupied preferentially by Ce4+. This also distinguishes it from closely related vitusite-(Ce) [Na3REE(PO4)2]. The relation of their unit cells is: ad = bv, bd = 3av, cd = 1/2cv. The distinct Ce4+ site in dyrnaesite-(La) has smaller coordination with shorter bond lengths than the other REE site in the same structure or the REE sites in vitusite-(Ce). It is adjacent to the predominately vacant Na site, which in its turn has the largest coordination of all Na sites in the structure. REE sites, or Na sites in a [010] row (similar to [100] in vitusite-(Ce)) assume two types of coordinations with and without mirror symmetry and two different configurations of surrounding PO4 tetrahedra. This summarizes the topological difference to vitusite-(Ce) where the corresponding coordinations are similar in the same row and intermediate in character to the two types in dyrnaesite-(La).

AB - Dyrnaesite-(La), Na7.89(Ce0.94Ca0.06)Σ1.00(La1.14Ce0.40Pr0.10Nd0.24Ca0.12)Σ2.00(PO4)6 is orthorhombic, Pnma, a = 18.4662(7), b = 16.0106(5), c = 7.0274(2) Å, V = 2077.7(1) Å3, Z = 4. The crystal structure is related to the group of Na3REE(XO4)2 compounds (with X = P, V, As), based on the aphthitalite/glaseritestructural type. Dyrnaesite is distinct in having ordered Na vacancies, and a rare-earth element (REE) site occupied preferentially by Ce4+. This also distinguishes it from closely related vitusite-(Ce) [Na3REE(PO4)2]. The relation of their unit cells is: ad = bv, bd = 3av, cd = 1/2cv. The distinct Ce4+ site in dyrnaesite-(La) has smaller coordination with shorter bond lengths than the other REE site in the same structure or the REE sites in vitusite-(Ce). It is adjacent to the predominately vacant Na site, which in its turn has the largest coordination of all Na sites in the structure. REE sites, or Na sites in a [010] row (similar to [100] in vitusite-(Ce)) assume two types of coordinations with and without mirror symmetry and two different configurations of surrounding PO4 tetrahedra. This summarizes the topological difference to vitusite-(Ce) where the corresponding coordinations are similar in the same row and intermediate in character to the two types in dyrnaesite-(La).

KW - Faculty of Science

U2 - 10.1180/minmag.2016.080.096

DO - 10.1180/minmag.2016.080.096

M3 - Journal article

SN - 0026-461X

VL - 81

SP - 199

EP - 208

JO - Mineralogical Magazine

JF - Mineralogical Magazine

IS - 1