Dioctahedral 2:1 layer silicates

Drits V A (1975) The stmctural and crystallochemical features of layer silicates. In Ciystallochemistiy of Minerals, and Geological Problems. AG Kossovskaya (ed), Nauka, Novosibirsk, p 35-51 (in Russian) Drits VA, Besson G, Muller F (1995) An improved model for stmctural transformations of heat-treated aluminous dioctahedral 2 1 layer silicates. Clays Clay Minerals 43 718-731 Drits VA, Lindgreen H, Saly n AL (1997) Determination of the content and distribution of fixed anunonium in illite-smectite by X-ray diffraction Apphcationto North Sea ilhte-smectite. Am Mineral 82 79-87 Drits VA, Lindgreen H, Salyn AL, Ylagan R, McCarty DK (1998) Semiquantitative determination of trans-vacant and cis-vacant 2 1 layers in ilhtes and ilhte-smectites by thermal analysis and X-ray diffraction. Am Mineral 83 1188-1198... 

Daynyak LG, Drits VA, Heffits LM (1992) Computer simulation of cation distribution in dioctahedral 2 1 layer silicates using IR-data application to Mossbauer spectroscopy of a glauconite sample. Clays Clay Minerals 40 470-479... 

Synthesis of Dioctahedral 2 1 Layer Silicates in an Acid and Huoride Medium... 

Hydrothermal synthesis of pure dioctahedral 2 1 layer silicates has been attempted to prt uce the starting material for pillared clays. Natural layer silicates have an unreliable quality, and a large variation in the nature and content of impurities. 

In all experiments, the synthesis of dioctahedral 2 1 layer silicates with various (Si/Al)iv ratios was performed in both acid and fluoride media. 

NMR spectra, and chemical analysis by X-ray fluorescence, the five samples El to E5 are dioctahedral 2 1 layer silicates, mainly constituted of Si and Al as framework-forming elements, containing Al for Si substitutions in tetrahedral layers and fluorine for hydroxyl groups substitutions. 29Si MAS NMR spectroscopy gives rise to their (Si/AI)iv tetrahedral ratio with a good reliability (Table 10-5). The well-controlled and well-known hydrogels composition indicates that only dioctahedral layer silicates, with two Al and one vacancy per... 

The development of synthesis in an acid and fluoride medium has been attempted in order to obtain dioctahedral 2 1 layer silicates, containing Si and A1 as fiamework-forming elements, under smooth synthesis conditions, industrially easy, and as near as possible to zeolites (low-temperature and low-pressure). 

Synthesis and characterization have been investigated in the case of M-dioctahedral 2 1 layer silicates with M = Li, Na, K, NH4 and (C2Hs)4N, and Si and A1 as structure elements. Syntheses were easily performed with Li+, Na+, and NH4+ they were more difficult with K+ and (C2H5)4N+. 

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