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Polytypism of Ln(SeO3)(HSeO3)·2H2O compounds: synthesis and crystal structure of the first monoclinic modification of Nd(SeO3)(HSeO3)·2H2O, DFT calculations and order/disorder descriptionстатья
- Авторы: Murtazoev A.F., Berdonosov P.S., Aksenov S.M., Kuznetsov A.N., Dolgikh V.A., Nelyubina Y.V., Merlino S.
- Журнал: Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
- Том: 79
- Номер: 2
- Год издания: 2023
- Издательство: International Union of Crystallography
- Местоположение издательства: United Kingdom
- DOI: 10.1107/S2052520622012227
- Аннотация: Compounds with the general formula Ln3+(SeO3)(HSeO3)2H2O, where Ln =Sm3+, Tb3+, Nd3+ and Lu3+, are characterized by orthorhombic symmetry withspace group P212121 and unit-cell parameters in the ranges a 6.473–6.999, b 6.845–7.101, c 16.242–16.426 A˚ . Light-purple irregularly shaped crystals of anew monoclinic polytype of neodymium selenite Nd(SeO3)(HSeO3)2H2O havebeen obtained during a mild-condition hydrothermal synthesis. The monoclinicunit-cell parameters are: a = 7.0815 (2), b = 6.6996 (2), c = 16.7734 (5) A˚ , =101.256 (1), V = 780.48 (6) A˚ 3; space group P21/c. The crystal structures ofNd(SeO3)(HSeO3)2H2O polymorphs show order–disorder (OD) character andcan be described using the same OD groupoid family, more precisely a family ofOD structures built up from two kinds of non-polar layers (category IV). Thefirst monoclinic maximum degree order (MDO) structure (MDO1-polytype)with space group P21/c can be obtained when the inversion centre is active in theL2n-type layers, while the second MDO structure (MDO2-polytype) isorthorhombic with space group P212121 and can be obtained when the [21 - -]operation is active in the L2n-type layers. The structural complexity parametersand DFT calculations of both polytypes show that the polytype structures areextremely close energy-wise and almost equally viable from the point of totalenergy of the structure.
- Добавил в систему: Бердоносов Петр Сергеевич