Surface Microtopography of Lath-Shaped Hydrothermal Illite by Tapping-Mode™ and Contact-Mode AFM

Abstract

Abstract--Lath-shaped hydrothermal illite particles in Izumiyama pottery stone were examined by contact-mode atomic force microscopy (CMAFM) and tapping-mode AFM (TMAFM) in air. With CMAFM, the lath-shaped particles showed interlacing patterns on the (001) surface in deflection images, while in height images such patterns were unclear. Also, evidence of artifacts caused by frictional forces between the surface and tip and/or edge effects were found in the CMAFM height images of the particle and Si substrate surfaces. In contrast, TMAFM showed interlacing patterns clearly in both amplitude and height images, and artifacts were barely evident. The TMAFM height images permitted the accurate measurement of 1.0-or 2.0-nm height steps corresponding to single or double mica layers, as well.Many lath-shaped particles in the Izumiyama hydrothermal illite exhibit interlacing patterns on their (001) surface, as shown by these AFM observations. The interlacing patterns are characterized by polygonal spirals with comparatively wide spacings and steps having a height of 1.0 or 2.0 nm. Generally a single lath-shaped particle has a single spiral center on the (001) surface, and 2 mica layers rotated 120 ~ originate from the dislocation point. These support the view that lath-shaped illites belong to the 2M~ polytype. It is likely that these illite particles were formed by a uniform process of development that is characterized by very slow growth, spiral mechanisms in that growth and low supersaturation conditions.

Atomic Force Microscopy Study of Hydrothermal Illite in Izumiyama Pottery Stone from Arita, Saga Prefecture, Japan

“…Hydrothermal illite, sample IZ-2, (Hirasawa and Uehara, 1999) used in the experiment, was obtained from Izumiyama pottery stone from Arita, Saga prefecture, Japan, and is the same sample as described previously by Kuwahara et al (1998). Sample IZ-2 is a white clayey ore from illite veins of the inner illite zone (Nakagawa et al, 1995) and is nearly pure illite, for which the polytype is a mixture of 1M and 2M~, based on XRD (Hirasawa and Uehara, 1999).…”

“…We collected both parallel height ( Figure (Kuwahara et al, 1998). The amplitude image is essentially a record of the error in the height image under a constant force mode, and amplifies the stepped appearance on the surface.…”

“…1 M laths and 2M~ platelets (Inoue et al, 1987(Inoue et al, , 1988Baronnet, 1992). Kuwahara et al (1998), however, showed by AFM that many lathshaped hydrothermal illite particles in the Izumiyama pottery stone from Saga prefecture, Japan, exhibit interlaced spiral patterns on their (001) surfaces, supporting the existence of a 2M~ polytype. These results are inconsistent with the previous conclusion regarding the shapes of 1M laths and 2M~ platelets based on TEM and XRD studies.…”

“…For example, the crystal shapes and sizes of illite particles from sedimentary basins can provide information regarding the rate law for illite growth kinetics in sandstone reservoirs (Nagy, 1994). The morphology of the growth spirals of micas can potentially yield information on the solution saturation state during crystal growth (Blum, 1994;Kitagawa, 1998), and it is very important to obtain an understanding of growth mechanisms and polytypism (Baronnet, 1972;Kuwahara et al, 1998).…”

“…The use of AFM for clay particles permits morphological measurements of high accuracy, including particle dimensions, step heights, and step separations and the determination of many properties of individual particles, that cannot be obtained by other techniques ( Lindgreen et al, 1991Lindgreen et al, , 1992Blum, 1994;Nagy, 1994;Kuwahara et al, 1998). Polytype transformations from 1M to 2M~ in illite or muscovite is known to occur with increase in temperature and/or with decrease in the supersaturation of a solution (Velde, 1965;Mukhamit-Galeyev et al, 1985;Inoue et al, 1987Inoue et al, , 1988Baronnet, 1992).…”