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GEOREF RECORD

Transmission electron microscopy of synthetic 2- and 6- line ferrihydrite

Dawn E. Janney, John M. Cowley and Peter R. Buseck
Transmission electron microscopy of synthetic 2- and 6- line ferrihydrite
Clays and Clay Minerals (February 2000) 48 (1): 111-119

Abstract

High-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), annular dark-field scanning transmission electron microscope (STEM) images, and electron nano-diffraction were used to examine structures of synthetic 2- and 6-line ferrihydrite specimens. HRTEM images of 2-line ferrihydrite (2LFh) show scattered small ( approximately 1-3 nm) areas with lattice fringes surrounded by areas free of fringes. All SAED patterns show two bright rings corresponding to d-values of approximately 0.15 and 0.25 nm; each ring has a conspicuous shoulder on each side. Faint rings corresponding to d-values of 0.08, 0.095, 0.100, 0.106-0.114 (very broad ring), and 0.122 nm are visible in strongly exposed SAED patterns. Nanodiffraction patterns show conspicuous streaks and a lack of superlattice formation. HRTEM images of 6-line ferrihydrite (6LFh) display larger crystallites (typically approximately 5-6 nm) with lattice fringes visible in many thin areas. SAED patterns show rings corresponding to d-values of 0.148, 0.156, 0.176, 0.202, 0.227, and 0.25-0.26 nm and a shoulder extending between d-values of approximately 0.25 and 0.32 nm. Faint rings corresponding to d-values of 0.086, 0.093, 0.107, 0.112, 0.119, 0.125, and 0.135 nm are visible in strongly exposed SAED patterns. Small quantities of hematite, magnetite or maghemite, and an acicular material tentatively identified as goethite were observed in the 6-line ferrihydrite, but these quantities do not contribute significantly to the overall diffracted intensity from the sample.


ISSN: 0009-8604
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 48
Serial Issue: 1
Title: Transmission electron microscopy of synthetic 2- and 6- line ferrihydrite
Affiliation: Arizona State University, Department of Geology, Tempe, AZ, United States
Pages: 111-119
Published: 200002
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 41
Accession Number: 2000-033937
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200011
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