Abrupt Structural Transformation in Hydrotalcite-like Compounds Mg1-xAlx(OH)2(NO3)x·nH2O as a Continuous Function of Nitrate Anions
Abrupt Structural Transformation in Hydrotalcite-like Compounds Mg1-xAlx(OH)2(NO3)x·nH2O as a Continuous Function of Nitrate Anions
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DOI：
10.1021/jp0029257
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发表时间：
2001-02
影响因子：
3.3
通讯作者：
Z. X. and;H. Zeng
中科院分区：
文献类型：
--
作者：
Z. X. and;H. Zeng
本文采用XRD/FTIR/CHN/ICP系统研究了水滑石类化合物mgo - xalx (OH)2(NO3)x·nH2O随硝酸盐阴离子（x = 0.18−0.34）的连续函数的结构转变。通过x值的七个精细划分步骤，发现了基间距与硝酸盐阴离子含量（以及三价阳离子含量）之间的明确关系。特别是，我们已经能够“捕获”位于突然结构转变中点的中间类水滑石相。与普通水滑石不同的是，我们在Mg1-xAlx(OH)2(NO3)x·nH2O硝化样品中发现的关系要复杂得多。晶格参数a随着硝酸盐含量的增加而减小，参数c在x = 0.18 ~ 0.22时略有减小，在x = 0.26时随着硝酸盐阴离子的进一步增加而急剧上升，然后在x = 0.31 ~ 0.34时达到最大值。当x = 0.26时，化合物的平均晶粒尺寸也急剧减小。突然的结构变化…
We report here a systematic XRD/FTIR/CHN/ICP investigation for structural transformation of hydrotalcite-like compounds Mg1-xAlx(OH)2(NO3)x·nH2O as a continuous function of nitrate anions (x = 0.18−0.34). With seven finely divided steps in x value, a clear relationship between basal spacing and nitrate anion content (and thus trivalent cation content) has been found. In particular, we have been able to “arrest” an intermediate hydrotalcite-like phase that situates at the midpoint of an abrupt structural transformation. Unlike that of normal hydrotalcites, the relationship revealed in our nitrated Mg1-xAlx(OH)2(NO3)x·nH2O samples is much more complicated. While the lattice parameter a decreases with increase of nitrate content, the parameter c decreases slightly over x = 0.18−0.22, rises abruptly with a further increase of nitrate anions at x = 0.26, and then reaches maximums at x = 0.31−0.34. The compound at x = 0.26 also shows a sharp decrease in mean crystallite dimension. The abrupt structural change i...