Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Shang, C. Articles by Lin, J.-S. Search for Related Content GeoRef GeoRef Citation

MEASUREMENT OF ILLITE PARTICLE THICKNESS USING A DIRECT FOURIER TRANSFORM OF SMALL-ANGLE X-RAY SCATTERING DATA

Chao Shang^1,, James A. Rice^1,*, Dennis D. Eberl² and Jar-Shyong Lin³

¹ Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA
² US Geological Survey, Suite E-123, 215 Marine Street, Boulder, CO 80303, USA
³ Solid State Division, Ridge National Laboratory, Oak Ridge, TN 37831, USA

^* E-mail address of corresponding author: james_rice{at}sdstate.edu

It has been suggested that interstratified illite-smectite (I-S) minerals are composed of aggregates of fundamental particles. Many attempts have been made to measure the thickness of such fundamental particles, but each of the methods used suffers from its own limitations and uncertainties. Small-angle X-ray scattering (SAXS) can be used to measure the thickness of particles that scatter X-rays coherently. We used SAXS to study suspensions of Na-rectorite and other illites with varying proportions of smectite. The scattering intensity (I) was recorded as a function of the scattering vector, q = (4 /) sin(/2), where is the X-ray wavelength and is the scattering angle. The experimental data were treated with a direct Fourier transform to obtain the pair distance distribution function (PDDF) that was then used to determine the thickness of illite particles. The Guinier and Porod extrapolations were used to obtain the scattering intensity beyond the experimental q, and the effects of such extrapolations on the PDDF were examined. The thickness of independent rectorite particles (used as a reference mineral) is 18.3 Å. The SAXS results are compared with those obtained by X-ray diffraction peak broadening methods. It was found that the power-law exponent () obtained by fitting the data in the region of q = 0.1–0.6 nm^–1 to the power law (I = I₀q^–) is a linear function of illite particle thickness. Therefore, illite particle thickness could be predicted by the linear relationship as long as the thickness is within the limit where <4.0.

Key Words: Direct Fourier Transform • Illite • Fundamental Particle • Particle Thickness • SAXS