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 the homogeneous hydrothermal reaction, the heterogeneous hydrothermal reaction can not only provide a modest supersaturated environment for the framework ions, but also lower the energy barrier required for the new phase nucleation, which is more conducive to the formation and growth of crystals. In this paper, the molar ratio of the addition amount of magnesia and the addition amount of silicon and aluminum in the soapstone, that is, the fixed initial material, is a certain value, and n (Mg) / n (Si + Al) = 3: 4], a series of samples with different Si / Al ratios were synthesized under different synthesis temperature and time conditions. The XRD patterns of all the samples showed characteristic diffraction peaks of layered silicate minerals, and d (060) ≥0.153 nm, indicating that saponite minerals were synthesized. Among them, when n (Si) / n (Al) = 5.43 to 7.89, the degree of crystallinity of the saponite is better. Experiments show that prolonging the time and increasing the synthesis temperature are favorable for the growth of saponite crystals. At lower temperatures (160 ° C), the heterogeneous phases in the sample are mainly brucite and analcime. The existence of brucite is mainly due to the rapid hydration of magnesia under alkaline conditions and the slow dissolution of brucite, whereas the analcierite is due to the slow release of Mg2 + resulting in the relative excess of Si4 + and Al3 + in the solution. Both of these heterozygosities gradually disappear as reaction time increases. At higher temperature (300 ℃), the degree of crystallinity of the saponite was significantly increased and a small amount of 1: 1 chrysotile was formed due to the local excess of Mg2 + due to the rapid release of Mg2 +.