The Effect of Synthetic Method and Annealing Temperature on Metal Site Preference in Al_1-xGa_xFeO₃

Journal Article · Thu Aug 15 00:00:00 EDT 2013 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic4007636· OSTI ID:1089572

Walker, James D.S.; Grosvenor, Andrew P. ^[1]

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1. Saskatchewan

Magnetoelectric materials couple both magnetic and electronic properties, making them attractive for use in multifunctional devices. The magnetoelectric AFeO₃ compounds (Pna2₁; A = Al, Ga) have received attention as the properties of the system depend on composition as well as the synthetic method used. Al_1–xGa_xFeO₃ (0 ≤ x ≤ 1) was synthesized by the sol–gel and coprecipitation methods and studied by X-ray absorption near-edge spectroscopy (XANES). Al L_2,3⁻, Ga K-, and Fe K-edge XANES spectra were collected to examine how the average metal coordination number (CN) changes with the synthetic method. Al and Fe were found to prefer octahedral sites, while Ga prefers the tetrahedral site. It was found that composition played a larger role in determining site occupancies than synthetic method. Samples made by the sol–gel or ceramic methods (reported previously; Walker, J. D. S.; Grosvenor, A. P. J. Solid State Chem. 2013, 197, 147–153) showed smaller spectral changes than samples made via the coprecipitation method. This is attributed to greater ion mobility in samples synthesized via coprecipitation as the reactants do not have a long-range polymeric or oxide network during synthesis like samples synthesized via the sol–gel or ceramic method. Increasing annealing temperature increases the average coordination number of Al, and to a lesser extent Ga, while the average coordination number of Fe decreases. This study indicates that greater disorder is observed when the Al_1–xGa_xFeO₃ compounds have high Al content, and when annealed at higher temperatures.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: FOREIGN
• OSTI ID: 1089572
• Journal Information: Inorganic Chemistry, Vol. 52, Issue (15) ; 08, 2013; ISSN 0020-1669
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: ENGLISH