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 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 HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Henriksen, R. B. Articles by Eggleston, C. M. Search for Related Content GeoRef GeoRef Citation

Atomic-scale observations of franckeite surface morphology

¹ Geological Institute, Copenhagen University, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
² Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming, 82071-3006, U.S.A.

Correspondence: ^* E-mail: stipp{at}geol.ku.dk

Franckeite, approximately Pb_4.6Ag_0.2Sn_2.5Fe_0.8Sb₂S_12.6, consists of alternating pseudohexagonal (H) and pseudotetragonal (Q) layers. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) of freshly cleaved franckeite, from San José, Bolivia, revealed the atomic structure of the pseudohexagonal component. On AFM images, the expected pattern with b = 3.2 Å was observed. STM revealed a 3 x 3 superstructure, with b’ = 6.3 Å, interpreted to be caused by tunneling effects. The pseudotetragonal layer was not identified in any images.

Layer modulation, which results from the non-commensurate fit of the alternating H and Q layers, was observed with both AFM and STM. Modulation waves are sinusoidal and regular and they are always parallel. The calibrated modulation wavelengths averaged to 3.77, 4.10, 4.45, and 4.74 nm (with uncertainty 0.10 nm) corresponding to pseudotetragonal/pseudohexagonal (Q/H) matches of 13/12, 14/13, 15/14, and 16/15, respectively. These correspond with observations made using bulk analytical methods on individual members from the franckeite-cylindrite family but scanning probe microscopy (SPM) was able to show that Q/H match varies on a local scale, with sharp domain boundaries. Domains can be on the order of 150 nm in width.

This article has been cited by other articles:

				E. Makovicky, V. Petricek, M. Dusek, and D. Topa Crystal structure of a synthetic tin-selenium representative of the cylindrite structure type American Mineralogist, November 1, 2008; 93(11-12): 1787 - 1798. [Abstract] [Full Text] [PDF]

				E. Makovicky Crystal Structures of Sulfides and Other Chalcogenides Reviews in Mineralogy and Geochemistry, January 1, 2006; 61(1): 7 - 125. [Full Text] [PDF]