氢氧化镁的结晶习性研究

Study on the Growth of Magnesium Hydroxide Crystals

本文用负离子配位多面体模型探讨了NaOH水热介质中Mg(OH)2晶体的结晶习性,提出了Mg(OH)2的水热改性属溶解-结晶机制、生长基元为Mg(OH)64-八面体的观点。Mg(OH)2-NaOH-H2O体系高温热力学计算和电阻在线检测结果间接验证了生长基元论点。理论推导表明:Mg(OH)64-八面体的共棱连接方式决定了Mg(OH)2的结晶习性。

The growth of Mg(OH)(2) crystals in NaOH hydrothermal solution was studied by the theoretic model of anion coordination polyhedra of growth units. The experimental results and the theoretical analysis indicated that the hydrothermal modification of Mg(OH)(2) was carried out via dissolution-crystallization route and octahedral Mg(OH)(6)(4-) was the growth units of Mg(OH)(2) crystals, which was supported further by the thermodynamic calculation results in Ma(OH)(2)-NaOH-H2O system at elevated temperature and the variation of electronic resistance of hydrothermal solution. The linkage of octahedral Mg(OH)(6)(4-) in edge direction produced Mg(OH)(2) crystals with the highest stability, which determined the final morphology of Mg(OH)(2) crystals.