水镁石的低温化学合成及其矿物学研究  

CHEMICAL SYNTHESIS OF BRUCITE AT LOW TEMPERATURES AND ITS MINERALOGICAL STUDIES

作　　者：徐宝龙[1] 郑永飞[1] 周根陶[1] 龚冰[1] 

机构地区：[1]中国科学技术大学地球和空间科学系,合肥230026

出　　处：《矿物学报》1998年第3期273-280,共8页Acta Mineralogica Sinica

基　　金：国家科学自然基金!49453003;中国科学院专项基金

摘　　要：在低温条件下应用氯化镁法、氧化铁法和氮化镁法三种不同化学方法合成了水镁石矿物，并对其进行了X射线衍射、扫描电镜和热分析研究。结果表明，三种不同方法合成的水镁石矿物的X射线衍射谱各有特点，对水镁石形貌的扫描电镜观察发现：氮化镁法合成产物呈六方板状；氧化镁法合成产物呈大的片状聚集体，但颗粒很小；氯化镁法合成产物多呈不规则粒状聚集体，粒度比较均匀。显然水镁石的形态受合成方法和条件的影响，特别氮化镁法合成的水镁石形状与温度有关，温度越高形状越复杂。差热和热重分析表明，氯化镁法合成水镁石的分解脱水特征温度比氧化镁法和氮化镁法合成水镁石的要低50℃左右，这可能与矿物颗粒的大小和形状有关。对这些合成水镁石的矿物学研究不仅具有材料科学意义，而且为研究天然水镁石成因和性质提供了实验室证据。Magnesium oxide, magnesium nitride and magnesium chloride were used as reactants,respectively, to synthesize brucite in aqueous solutions at low temperatures. All of the synthesis products were identified by XRD for crystal structure, by SEM for morphology and by thermoanalytical techniques(TGA and DTA) for thermo-parameter. The XRD resuIts show that there is a significant difference in crystallinity of the brucites synthesized by different methods. The morphological features of the synthetic brucites are as follows: the products synthesized by the magnesium-nitride method take the hexa-flaggy form; the products by the magnesium-oxide method are mass sheet assemblages having small particles; the products by the magnesium-chloride method are small irregularly granular aggregates with homogeneous grain size. Apparently, the synthetic methods and conditions have effects on the morphological features of brucite. Especially the shape of the synthetic products by the magnesium-nitride method is related to temperature, i. e., the higher the temperature, the more complicated the shape. The results of the DTA and TGA show that the dehydration temperature of the brucite synthesized by the magnesium-chloride method is about 50℃ less than that by the magnesium-nitride and magnesium-oxide methods. This is probably due to differences in size and shape of the brucites. The mineralogical studies of the synthetic brucites are not only of interest in material science, but also provide experimental evidence for studying the nature of natural brucite.

关 键 词：化学合成 水镁石 晶体形貌 矿物学 低温化学合成 

分 类 号：P578.74[天文地球—矿物学] P57[天文地球—地质学]