The growth mechanism of hydrotalcite crystal

From the point of growth units, the growth mechanism of hydrotalcite （HT） crystal is investigated in this paper. Results show that the growth morphology of HT is consistent with the model of anion coordination polyhedron growth units. The Raman shift of growth solutions of HT, Cu-HTlc, and Cu-Zn-HTlc are monitored using Raman spectroscopy. In the experiment, the growth units of Mg-Al-hydrotalcite are [Mg-（OH）6]4- and [Al-（OH）6]3-, and the growth units of Cu-Htlc and Cu-Zn-HTlc are [Mg-（OH）6]4- and [Al-（OH）6]3-, respectively. The growth process of hydrotalcite is as follows： growth units first incorpo- rate into metal layers, then metal layers adsorb An- and H2O, and the growth units incorporate into layer compounds according to this rule. Growth units will have different incorporations and growth morphologies caused by different growth surroundings. Furthermore, the reason why Cu-HTlc is difficult to synthesize is also interpreted in this paper.