Thermodynamic stability and atomic and electronic structure of reducedFe3O4(111) single-crystal surfaces

Abstract

Citation for published version (APA):Paul, M., Sing, M., Claessen, R., Schrupp, D., & Brabers, V. A. M. (2007). Thermodynamic stability and atomic and electronic structure of reduced Fe3 O4 (111) Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nl providing details and we will investigate your claim. Magnetite ͑111͒ single-crystal surfaces prepared in situ under different reducing conditions and-as a result-with varying stoichiometries have been studied by scanning tunneling microscopy, low-energy electron diffraction, and x-ray photoemission spectroscopy. The coexistence of several surface structures has been detected, indicating only small differences in their relative stabilities. In particular, an unusual previously unreported superstructure has been found for a strongly reduced surface. Its microscopic origin is discussed against the background of recent results from scanning tunneling microscopy of the oxidized magnetite ͑111͒ surface and from ab initio thermodynamics. Partly at variance with and partly complementary to these results, we regard as driving force elastic strain due to the lateral mismatch between Fe 3 O 4 substrate and Fe 1−x O-like overlayer.

Termination and Verwey transition of the (111) surface of magnetite studied by scanning tunneling microscopy and first-principles calculations

“…After undergoing this cleaning procedure, LEED exhibited the same patterns as those observed in previous studies. [11][12][13]25,26 The crystal gradually lost oxygen while under UHV for several months. Every time we found an oxygen deficient area in the STM images ͑see Sec.…”

“…The ͑111͒ surface of magnetite has been studied using various surface science techniques because of its importance in geochemistry, device application, and catalysis. 4 There are six atomic planes along the ͓111͔ direction, which can be written as, using notations used in previous studies, [11][12][13][14][15][16] Fe tet1 , O 1 , Fe oct1 , O 2 , Fe tet2 , and Fe oct2 . Adsorption and reaction of molecules on Fe 3 O 4 ͑111͒ have also been studied, but with the assumption of a certain type of termination.…”

“…4,12 RT STM on synthetic single crystals exhibited exactly the same surface structures as thin-film samples. 13,24 This surface is referred to as the "regular termination" in Refs. 13 and 24, and we hereinafter use the same terminology.…”

Determination of the surface electronic structure of Fe3O4(1 1 1) by soft X-ray spectroscopy

“…The variations in these observations are related to the oxygen partial pressure dependence and annealing temperatures in the preparation steps. For instance, FeO x (1 1 1)-like surface terminations have been reported as the samples were annealed at 870 K in 10 −6 Torr oxygen ambient [10,11]. It has also been shown that FeO x (1 1 1)-like reduced surface patches and regular surface regions can coexist on natural single crystals [12].…”

Adsorption of gold subnano-structures on a magnetite(111) surface and their interaction with CO

“…25 At room temperature, magnetite crystallizes in the inverse spinel structure with the tetrahedral positions occupied by ferric (Fe 3+ ) ions and an equal number of ferric and ferrous (Fe 2+ ) ions in the octahedral sites. [30][31][32][33][34] However, the results of more recent scanning tunneling microscopy (STM) experiments 35,36 and density functional theory (DFT) studies 29,[36][37][38][39][40][41] have shown unequivocally that the most stable (111) surface of magnetite corresponds to Fe tet1 termination (in the following referred to as Fe tet ). 26 The (111) surface is the predominant cleavage plane and is most commonly exposed on naturally grown magnetite crystals.…”