Nontronite: chemistry and x-ray diffraction
1977; Cambridge University Press; Volume: 12; Issue: 3 Linguagem: Inglês
10.1180/claymin.1977.012.3.01
ISSN1471-8030
Autores Tópico(s)X-ray Diffraction in Crystallography
ResumoAbstract Chemical and X-ray analysis of eight samples of nontronite are consistent with the Hofmann et al. montmorillonite structure. The finest fraction of some fully hydrated (15·3 Å) samples is composed of crystals all about 6 or 7 unit cells thick, and having 12 H 2 O per 8 Si, arranged at three levels in the interlayer, possibly as upright octahedra. During dehydration, non-integral 00 l sequences, and variations in d 001 result from a range of layer thickness in one crystal, caused by loss of water from the crystal periphery with consequent margin collapse. At about 50% relative humidity, the H 2 O content of nontronite is determined by the tetrahedral aluminium, probably because Al iv controls maximum crystal size.
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