Mössbauer evaluation of aerogel-prepared Fe2(MoO4)3

Fe-Mo-O binary oxides are among the catalysts for selective oxidation of, e.g., hydrogen sulfide and hydrocarbons. Their catalytic activities are composition- and structure-dependent. In this work Fe$_{2}$(MoO$_{4})_{3}$ was prepared first as aerogel in an autoclave, from starting materials of ferric acetylacetonate and dioxomolybdenum, then oxidized and annealed. M\"{o}ssbauer measurements were carried out to complement other techniques for structural and magnetic analysis. The data can be well fitted to two subspectra in the ratio of approximately 2:1. The major component remains as a singlet from 300 K down to 25 K, while a well-defined sextet representing a magnetic ordering gradually developed below 200 K for the other. Its hyperfine field, as well as the isomer shift and quadrupole splitting values for both subspectra were obtained.