The imbibition of divalent cations (Zn²⁺, Ni²⁺) into half the cation vacancies in Al(OH)₃ results in layered double hydroxides comprising positively charged layers of the composition [M□Al₄(OH)₁₂]²⁺ (□: cation vacancy). Nitrate ions were intercalated for charge neutrality together with water molecules. Structure refinement by the Rietveld method showed that the metal hydroxide crystallized in monoclinic symmetry (space group P12₁/n1). Upon heating to T = 160 °C, a new phase was obtained which was indexed to a two layer cell of orthorhombic symmetry, suggesting an interpolytype transformation. Using the idealized metal hydroxide layer (layer group p12₁/a1) as a structural synthon, the different ways of stacking these layers were predicted to arrive at the complete universe of polytypes in this class of compounds. Some of the predicted stacking sequences generated new 2-fold axes, not found in the layer group and resulted in one-layer, two-layer, and three different four-layer polytypes (1O, 2O, and 4O_1–3; O: orthorhombic) of orthorhombic symmetry. The high temperature phase can be described as a two-layer polytype (2O) (space group Pn2n) obtained by the rigid translation of the metal hydroxide layers by (1/4, 1/2) relative to one another. Cooling and rehydration restored the as-prepared phase of monoclinic symmetry.

中文翻译：

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M（Zn 2 ⁺，Ni ²⁺）和Al的铝酸盐状层状双氢氧化物的多型性：从单斜向对称的结构转变

二价阳离子（Zn组成的吸液²⁺，镍²⁺）以Al（OH）到一半的阳离子空位_3所导致层状双氢氧化物，其包括组合物的带正电荷的层[M□的Al ₄（OH）₁₂ ] ²⁺（ □：阳离子空位）。为了水的电荷中和，将硝酸根离子与水分子一起插入。通过Rietveld方法的结构细化表明，金属氢氧化物以单斜对称（空间群P 12 ₁ / n 1）结晶。加热至T＝ 160℃，获得了新相，该新相被索引为正交斜对称的两层细胞，表明存在多型转变。使用理想化的金属氢氧化物层（层组p 12 ₁ / a 1）作为结构合成子，预测这些层的不同堆叠方式将在此类化合物中形成完整的多型体。一些预测的堆积序列会生成新的2折轴，但在层组中找不到，并导致一层，两层和三种不同的四层多型（1O，2O和4O _1–3； O：正交的）。高温相可以描述为两层多型体（2O）（空间群Pn 2 n）是通过金属氢氧化物层相对于彼此刚性平移（1/4，1/2）而获得的。冷却和补液恢复了单斜对称的准备阶段。