皂石的异相水热合成及其影响因素  

Heterogeneous Hydrothermal Synthesis of Saponite and Factors Affecting its Crystallinity

作　　者：张旦[1,2,3] 何宏平[1,2] 陶奇[1,2] 陈漫游 吉世超 李甜[1] 

机构地区：[1]中国科学院矿物学与成矿学重点实验室,中国科学院广州地球化学研究所,广东广州510640 [2]广东省矿物物理与材料研究开发重点实验室,广东广州510640 [3]中国科学院大学,北京100049

出　　处：《矿物学报》2016年第2期241-246,共6页Acta Mineralogica Sinica

基　　金：国家自然科学基金(批准号:41530313;41372048);国家自然科学基金委-广东省联合基金(批准号:U1201233)

摘　　要：与均相水热反应相比,异相水热反应不仅可以提供一个骨架离子的适度过饱和环境,而且其新相成核所需逾越的能垒较低,更有利于晶体的形成和生长。本文采用异相水热法合成在皂石,即固定初始物料中氧化镁的添加量与硅、铝的添加量之和的摩尔比为一定值,n（Mg）/n（Si＋Al）=3∶4],在不同的合成温度和时间条件下合成了一系列不同Si/Al比的样品。所有样品的XRD图均呈现层状硅酸盐矿物的特征衍射峰,且d（060）≥0.153 nm,说明合成的是皂石矿物。其中,当n（Si）/n（Al）=5.43~7.89时,皂石的结晶度较好。实验表明,延长时间、提高合成温度有利于皂石晶体生长。在较低温度（160℃）下,样品中的杂相主要为水镁石和方沸石。水镁石相的存在主要归因于氧化镁在碱性条件下的快速水合及水镁石的慢速溶解,而方沸石则是由于Mg2＋释放缓慢,导致溶液中Si4＋及Al3＋相对过剩而形成。这两种杂相均会随着反应时间的延长而逐渐消失。在较高温度（300℃）下,皂石的结晶度明显升高,并由于Mg2＋的快速释放导致Mg2＋的局部过剩,因而形成了少量1∶1型的纤蛇纹石。Compared with homogeneous synthesis technology, heterogeneous synthesis can promote the nucleation and subsequently accelerate the growth of secondary minerals by providing a local environment with super-saturation of ion concentration and a relatively lower energy barrier. In the present study, a series of samples were synthesized by altering Si/Al ratio（fixing the Mg/（Si＋Al） =3∶4）, reaction temperature and time. Characteristic reflections of phyllosilicate were recorded in XRD patterns of the resulting products with d（060）≥0.153 nm, indicating a successful synthesis of saponite. The well-crystallized saponite was obtained in the initial Si/Al ratio range of 5.43–7.89, and their crystallinities increased with increasing reaction temperature and time. At a temperature of 160℃, brucite and analcime formed as impurities, resulting from the low dissolution ability of brucite and the excess of Si4＋ and Al3＋ in the solution. Both of them disappeared with extension of reaction time. At a temperature of 300℃, a small amount of chrysotile was formed, corresponding to the rapid release of Mg2＋.

关 键 词：皂石 异相水热合成 影响因素 纤蛇纹石 

分 类 号：P579[天文地球—矿物学]