VALI, H and HESSE, R and KOHLER, EE (1991) COMBINED FREEZE-ETCH REPLICAS AND HRTEM IMAGES AS TOOLS TO STUDY FUNDAMENTAL PARTICLES AND THE MULTIPHASE NATURE OF 2-1 LAYER SILICATES. AMERICAN MINERALOGIST, 76 (11-12). pp. 1973-1984. ISSN 0003-004X,
Full text not available from this repository.Abstract
Comparative studies of illite and glauconite dispersions (< 1.0-mu-m fraction) using transmission electron microscopy on freeze-etch replicas and ultrathin sections provide detailed information on surface morphology and layer structure of these 2:1 layer silicates. Results show that the arrangement of layer packets observed in ultrathin section is both a clumping artifact caused by dehydration required for embedding and a primary structure. Adjacent packets (40-150 angstrom) of 2:1 layers usually do not split along joint interfaces even in dilute and Na-saturated dispersions. The thickness of these packets imaged on ultrathin sections is in agreement with the size of illite "fundamental particles." However, they do not usually occur as free particles in dispersion. The thickness of individual free particles observed in freeze-etch replicas varies between 50 and 500 angstrom. Thus most free particles of illite and glauconite are composed of several packets. Treatment of samples with octadecylammonium ions reveals three different types of interlayer spacings corresponding to (1) a high-charged nonexpandable component (10 angstrom in XRD and HRTEM), (2) a high-charged expandable component (29-30 angstrom in XRD; 24 angstrom in HRTEM), and (3) a low-charged expandable component as single interlayers between adjacent packets and as expandable components in the 1:1 ordered mixed layers (no XRD peak; 16-17 angstrom in HRTEM). It is concluded that the illitic materials contain at least three distinct phases: a nonexpandable illite phase, an expandable illite phase, and a 1:1 ordered mixed-layer phase. The IIIS or IIIIS structures identified in XRD are due to interparticle diffraction. The smectite-like interlayers in ordered mixed-layer clays do not represent a separate phase.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TRANSMISSION ELECTRON-MICROSCOPY; ILLITE SMECTITE; SILVERTON CALDERA; CLAY PARTICLES; INTERPARTICLE-DIFFRACTION; INTERSTRATIFIED CLAYS; STRUCTURAL DISORDER; MINERALS; CHARGE; SERICITE; |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:46 |
| URI: | https://pred.uni-regensburg.de/id/eprint/54796 |
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