The beidellite-saponite series; an experimental approach
The beidellite-saponite series; an experimental approach
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DOI：
10.1127/ejm/5/4/0623
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发表时间：
1993-07
影响因子：
2.1
通讯作者：
O. Grauby;S. Petit;A. Decarreau;A. Baronnet
中科院分区：
文献类型：
--
作者：
O. Grauby;S. Petit;A. Decarreau;A. Baronnet
在200-250°C温度范围内，用合成方法对蒙脱石中的八面体Al-Mg系列进行了研究。所有合成的粘土四面体充电，从而导致固溶体之间的贝得石和皂石端员。TEM化学微区分析表明，在粘土颗粒尺度上（平均颗粒尺寸约1 μm，堆积近10层），Al-Mg系在这两个端元之间是连续的，没有化学间隙。通过X射线衍射（在50和150 A之间的晶格相干尺度）的研究表明三种不同类型的干涉相干畴：（1）基本上为铝的二八面体相干畴，（2）基本上为镁的三八面体相干畴和（3）中间相干畴。在大多数样本中，两种类型的域相关联。具有中间八面体化学性质的样品由具有恒定化学性质的堆叠层的颗粒组成，因此显示出明显的二三八面体晶格。然而，时间研究表明这种特殊的晶格是亚稳态的。沿着系列，根据IR数据，Al 3+和Mg 2+阳离子呈现出强烈的偏聚倾向。在粘土颗粒尺度上看起来连续的贝得石-皂石八面体系列，实际上是由相关的不同晶格或团簇组成的，如在更细尺度上的研究所示。因此，真正的固溶体呈现出很大的可溶解性差距
The study of the octahedral Al-Mg series in smectites was conducted using synthesis methods at 200-250°C. All synthesized clays were tetrahedrally charged thus leading to a solid-solution between beidellite and saponite end-members. The TEM chemical microanalyses indicated that the Al-Mg series was continuous between these two end-members without chemical gap, at the clay particle scale (mean particle dimension about 1 μm and stacking of almost ten layers). The investigations by X-ray diffraction (at the scale of lattice coherences between 50 and 150 A) indicated three different kinds of interferential coherence domains: (1) a dioctahedral essentially aluminous one, (2) a trioctahedral essentially magnesian one and (3) an intermediate one. In most samples, two kinds of domains are associated. A sample with an intermediate octahedral chemistry was made up of particles with stacked layers having a constant chemistry and, thus, showing an apparent ditrioctahedral lattice. However, time studies show this special lattice to be metastable. Along the series and according to IR data, Al 3+ and Mg 2+ cations present a strong segregation tendency. The beidellite-saponite octahedral series which appears continuous at the clay particle scale is, in fact, made up of associated different lattices or clusters, as shown by the study at a finer scale. So, the true solid-solution presents a wide miscibility gap