TEM-assisted dynamic scanning force microscope imaging of (001) antigorite: Surfaces and steps on a modulated silicate
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Elisa Palacios-Lidon
Abstract
Ultra-high vacuum dynamic scanning force microscopy (dynamic SFM) has been performed on in situ cleaved and as-grown (001) surfaces of low-T, m = 18 and m = 20, antigorite from the Kovdor Mine, Russia. The internal microstructure of the same crystal before cleavage has been checked by conventional TEM on FIB-cut cross-sections. The structural wave is imaged by dynamic SFM with a ~0.25 nm topographic amplitude (outcropping tetrahedral sheet) on cleaved and as-grown surfaces, and with a ~0.5 nm topographic amplitude (outcropping tetrahedral + octahedral sheets) mostly found on cleaved surfaces. Atomic resolution imaging was successfully applied on the cleavage surface through imaging individual atomic features on the outer hexagonal net of the emerging (Mg, O, OH) octahedra of the half-wave. The antigorite cleavage crack undulates through a single octahedral sheet, thereby avoiding rupture of strong Si-O bonds. The two tetrahedral reversals, which form the edges of the modulation repeat, are found to be strongly non-equivalent in structure: across <010>, one reversal is sharp as expected from the standard models of the antigorite structure, whereas the other reversal is unexpectedly “extended.” The latter suggests some scheme of anti-polar positioning of silicate tetrahedra along <010> at the 6-membered ring reversal. High-resolution transmission electron microscopy (HRTEM) structure imaging of antigorite viewed down to <010> confirms spread out electron densities at this reversal. Numerous step height measurements on (001) surfaces show incremental results as integral multiples of 0.25 nm, the spacing between O,OH surfaces along c*. Many of them differ in height from integral multiples of the unit cell repeat along c* and could be explained from carving the bulk wave structure. For all surfaces and steps, local stoichiometry and global electro-neutrality of the surface are satisfied.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- TEM-assisted dynamic scanning force microscope imaging of (001) antigorite: Surfaces and steps on a modulated silicate
- PH₂O-dependent structural phase transitions in the zeolite mesolite: Real- and reciprocal-space crystal structure refinements
- The crystal structure of esperite, with a revised chemical formula, PbCa2(ZnSiO4)3, isostructural with beryllonite
- Dendritic zircon formation by deterministic volume-filling fractal growth: Implications for the mechanisms of branch formation in dendrites
- Enthalpies of formation of pyrrhotite Fe1–0.125xS (0 ≤ x ≤ 1) solid solutions
- Crystal chemistry of synthetic lawsonite solid-solution series CaAl2[(OH)2/Si2O7]·H2O– SrAl2[(OH)2/Si2O7]·H2O and the Cmcm–P21/m phase transition
- Coulsellite, CaNa3AlMg3F14, a rhombohedral pyrochlore with 1:3 ordering in both A and B sites, from the Cleveland Mine, Tasmania, Australia
- Synthesis and characterization of zeolite 4A-type desiccant from kaolin
- Effect of iron on the compressibility of hydrous ringwoodite
- Kapundaite, (Na,Ca)2Fe4 3+(PO4)4(OH)3·5H2O, a new phosphate species from Toms quarry, South Australia: Description and structural relationship to mélonjosephite
- Rate of antigorite dehydration at 2 GPa applied to subduction zones
- IR absorption coefficients for water in nominally anhydrous high-pressure minerals
- Experimental techniques for determining tin solubility in silicate melts using silica capsules in 1 atm furnaces and rhenium capsules in the piston cylinder
- Cassiterite-saturated minimum melting behavior within Sn-SnO2-SiO2 at 1 atm and 10 kbar
- Cr-bearing tourmaline associated with emerald deposits from Swat, NW Pakistan: Genesis and its exploration significance
- Mechanism and kinetics of reduction of a FeO-Fe2O3-CaO-MgO aluminosilicate melt in a high-CO-activity environment
- Biodurability of chrysotile and tremolite asbestos in simulated lung and gastric fluids
- High-pressure behavior of Ca/Na clinopyroxenes: The effect of divalent and trivalent 3d-transition elements
- Uvarovite from chromite-bearing ultramafic intrusives, Orissa, India, a crystal-chemical characterization using 57Fe Mössbauer spectroscopy
- An X-ray Rietveld and infrared spectral study of the Na2(Mn1–xM2+x )Fe2+Fe3+(PO4)3 (x = 0 to 1 and M2+ = Mg, Cd) alluaudite-type solid solutions
- Dissolution kinetics of anorthite in a supercritical CO2–water system
- Evaluation of the elasticity normal to the basal plane of non-expandable 2:1 phyllosilicate minerals by nanoindentation
- 57Fe Mössbauer spectroscopy and electrical resistivity studies on naturally occurring native iron under high pressures up to 9.1 GPa
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