Sodium chlorate (NaClO₃) crystals change from a cuboid to a tetrahedron of {1̅1̅1̅} morphology when crystallized in the presence of sodium dithionate (Na₂S₂O₆) impurity. Polarized extended X-ray absorption fine structure at the S K-edge, used to probe the local structure around this impurity with respect to its orientation within the bulk crystal lattice, reveals that the S–S bond of the S₂O₆^2– ions is closely aligned along the <111>/<1̅1̅1̅> lattice direction. High resolution diffraction studies using X-ray multiple diffraction reveal growth-induced anisotropy in the doped crystals associated with subtle lattice distortions in the symmetry-independent {1̅1̅1̅} and {111} growth sectors. The data are consistent with a mechanistic model involving the creation of lattice vacancies and the substitution of one of the SO₃ anionic groups of the dopant ion for a host ClO₃ ion when incorporated at the {1̅1̅1̅} growth interface with the other SO₃ group substituting for one or more anionic sites in the succeeding growth layer depending on the degree of impurity concentration within the crystallization solution. This mechanism is also fully consistent with the formation of twinning at higher impurity concentrations previously reported by Lan et al. Cryst. Growth & Des. 2014, 14, 6084–6092.

中文翻译：

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二硫酸盐离子的结构环境及其在氯酸钠的晶体习性改性中的作用的表征。

当在二硫酸钠（Na ₂ S ₂ O ₆）杂质存在下结晶时，氯化钠（NaClO ₃）晶体从长方体变为{1̅1̅1̅}形态的四面体。在S K边缘的极化扩展X射线吸收精细结构，用于探测该杂质周围的局部结构（相对于其在大晶格中的方向），揭示出S ₂ O ₆ ^2–的S–S键离子沿<111> / <1̅1̅1̅>晶格方向紧密排列。使用X射线多重衍射的高分辨率衍射研究显示，在与晶体无关的{1̅1̅1̅}和{111}生长区中，掺杂晶体中的生长诱导各向异性与微妙的晶格畸变有关。该数据与一种机理模型相一致，该机理涉及晶格空位的产生以及在{1̅1̅1̅}生长界面处与另一种SO ₃结合时，掺杂离子的SO ₃阴离子基团之一取代了主体ClO ₃离子。取决于结晶溶液中杂质浓度的程度，在随后的生长层中取代一个或多个阴离子位点的基团。这种机理也与Lan等人先前报道的在较高杂质浓度下孪晶的形成完全一致。水晶 成长与目标。 2014，14，6084-6092。