Electronic and Optical Properties of a Semiconducting Spinel (Fe2CrO4). (13th January 2017)

• Record Type: Journal Article
• Authors: Chambers, Scott A.; Droubay, Timothy C.; Kaspar, Tiffany C.; Nayyar, Iffat H.; McBriarty, Martin E.; Heald, Steve M.; Keavney, David J.; Bowden, Mark E.; Sushko, Peter V.
• Is Part Of: Advanced functional materials. Volume 27:Number 9(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-01-13
• Subjects: chromium ferrite -- epitaxial films -- photoelectronic properties; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201605040
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract : Epitaxial chromium ferrite (Fe2 CrO4 ), prepared by state‐of‐the‐art oxygen plasma assisted molecular beam epitaxy, is shown to exhibit unusual electronic transport properties driven by the crystallographic structure and composition of the material. Replacing 1/3 of the Fe cations with Cr converts the host ferrimagnet from a metal into a semiconductor by virtue of its fixed valence (3+); Cr substitutes for Fe at B sites in the spinel lattice. By contrast, replacing 2/3 of the Fe cations with Cr results in an insulator. Three candidate conductive paths, all involving electron hopping between Fe 2+ and Fe 3+, are identified in Fe2 CrO4 . Moreover, Fe2 CrO4 is shown to be photoconductive across the visible portion of the electromagnetic spectrum. As a result, this material is of potential interest for important photo‐electrochemical processes such as water splitting. Abstract : A qualitatively different mode of conductivity is activated in magnetite by doping one third of the Fe cation sites with Cr. Experimental data and ab initio modeling results establish the structure, and then point to different electron hopping paths becoming operative, as Cr 3+ replaces Fe 3+ in the octahedral sites of the spinel lattice.