Abstract
The crystal structure of Na2Mn3(SO4)4 [unit-cell parameters a = 14.8307 (18), b = 9.9107 (18), c = 8.6845 (12) Å, space group Cmc21] displays order–disorder (OD) character and can be described using the OD groupoid family, more precisely a family of OD structures built up by two types of non-polar layers, with layer symmetry P(m)c21 (L
2n+1 type) and P(b)cm (L
2n
type) (category IV). A new hypothetical MDO2 polytype has been proposed and the geometry optimization demonstrates its reasonability as another possible stable polytype. Compounds Na2Mn3–x
Mg
x
(SO4)4 with the unit-cell parameters a ∼ 29.2–29.7 Å, b ∼ 9.5–9.9 Å, c ∼ 8.7 Å and space group Pbca can be described in terms of modularity as a sequence of A, S
1 and S
2 modules:…|AS
1
AS
2
AS
1
AS
2|… or (AS
1
AS
2), together with MDO1 (AS
1
AS
1) and MDO2 (AS
2
AS
2). The crystal structures of itelmenite, NaCaFe3+
3(PO4)4, and Ca2MgFe3+
2(PO4)4 are crystal-chemical isotypic to Na2Mn3–x
Mg
x
(SO4)4 and should be considered as (A*S
1
A*S
2) derivatives of the (AS
1
AS
2)-type structure.
Funder
Russian Science Foundation
Publisher
International Union of Crystallography (IUCr)
Subject
Materials Chemistry,Metals and Alloys,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials
Cited by
4 articles.
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