Dissymmetrization in Eudialyte-Group Minerals. III: Peculiarities of the High-Order Voronkovite Р3-Structure

IF 0.6 4区材料科学 Q4 CRYSTALLOGRAPHY

Crystallography Reports Pub Date : 2025-02-16 DOI:10.1134/S1063774524602193

R. K. Rastsvetaeva, V. M. Gridchina, S. M. Aksenov, N. V. Chukanov

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Abstract

The re-study of the crystal structure of the second find of low-calcium and rare-earths bearing voronkovite in the Lovozero alkaline complex, Kola Peninsula has revealed new features of its structure, which lower the symmetry of the mineral. Ordering of Ca, Mn, Ce, and Na atoms in octahedra of six-membered rings, as well as Zr, Fe, and Na atoms in M2 positions, combining translationally identical six-membered rings as well as Nb, Ti, and Si atoms and vacancies in axial fragments of the structure, has been established within the P3 symmetry. The trigonal-cell parameters of the mineral are a = 14.1617(1) Å, c = 30.1815(1) Å, and V = 5242.09(4) Å³; the number of independent positions is 184. The crystal structure has been refined to the R factor of 3.74% in the isotropic atomic displacement approximation using 8257 reflections with F > 3σ(F). The main features of voronkovite in comparison with the minerals investigated previously within the framework of the sp. gr. P3 are discussed.

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对科拉半岛洛沃泽罗碱性复合体中第二次发现的含低钙和稀土元素的伏龙伏虎石晶体结构的重新研究揭示了其结构的新特征，从而降低了该矿物的对称性。六元环八面体中 Ca、Mn、Ce 和 Na 原子的排序，以及 M2 位置上 Zr、Fe 和 Na 原子的排序，结合平移相同的六元环以及 Nb、Ti 和 Si 原子以及结构轴向片段中的空位，已在 P3 对称性中确立。该矿物的三元胞参数为 a = 14.1617(1) Å，c = 30.1815(1) Å，V = 5242.09(4) Å3；独立位置数为 184。在各向同性原子位移近似条件下，利用 F > 3σ(F)的 8257 次反射，晶体结构的 R 系数被精制为 3.74%。讨论了沃龙孔铁矿与之前在 sp.

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来源期刊

Crystallography Reports 化学-晶体学

CiteScore

1.10

自引率

28.60%

发文量

审稿时长

4-8 weeks

期刊介绍： Crystallography Reports is a journal that publishes original articles short communications, and reviews on various aspects of crystallography: diffraction and scattering of X-rays, electrons, and neutrons, determination of crystal structure of inorganic and organic substances, including proteins and other biological substances; UV-VIS and IR spectroscopy; growth, imperfect structure and physical properties of crystals; thin films, liquid crystals, nanomaterials, partially disordered systems, and the methods of studies.