ISSN:
1435-1536
Keywords:
Biotite
;
silicate layers
;
vermiculite structure
;
mica-vermiculite transformations
;
ultramicrotome sections
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Particle size fractions of biotite (0.5–2; 2–5; 5–20; 20–50 μ) were gradually transformed to vermiculite by exchanging the interlayer potassium with barium. In a subsequent exchange procedure, interlayer barium was removed by n-alkylammonium ions in order to preserve the expanded structure under the conditions in the electron microscope. Ultramicrotome sections cut perpendicular to the plane of silicate layers were prepared from samples representing different states of mica-vermiculite transformation. Inspection of lattice images in the HRTEM revealed two characteristic phenomena. During the initial phase of the transformation, mineral particles are dissected by a growing number of single expanded interlayers separating packets of contracted layers. In a later stage, a step-wise expansion of adjacent interlayers can be observed producing a wedge-shaped profile of the mica-vermiculite interface. A statistical treatment of these observations is necessary for relating the mechanism of lattice expansion quantitatively to cooperative phenomena frequently found in studying the kinetics of intercalation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01411506
Permalink
