Magnesium Doped Hercynite: Preparation and Formation Mechanism
We investigated the formation mechanism of magnesium doped hercynite during reaction sintering process at 1400 ºC. A two-step synthesis procedure based on combining of spinel and ferrous chloride was considered here. Firstly, magnesium aluminate spinel was prepared by sol-gel method, using Al and Mg chlorides as raw materials. Then, the powder particles were dispersed in an aqueous solution of ferrous chloride in 1.5:1 molar ratio and the solution was stirred at 60 °C. After solvents removal, the thermal properties of a sample of the dried specimens were studied, using simultaneous thermal analysis (STA) method. Afterwards, the specimens were calcined at 400, 800, 1100 and 1400 ºC for 1, 3 and 6 hrs, under air atmosphere. X-ray diffraction (XRD) analysis, field emission scanning electron microscope (FESEM) and X-ray fluorescence spectroscopy (XRF) were used for characterization of the specimens. Study of the obtained results leads us to conclude that hercynite was formed thorough a diffusion-based mechanism, when heated to high enough temperatures. After heating for a prolonged period (6 hrs.) at 1400 °C, hercynite decomposes into its constituent oxides and also a new crystal phase appears. This new phase was identified as FeAlO3. The modified Scherrer, Williamson-Hall and Rietveld methods are also used to estimate the crystallite size of the as-synthesized magnesium doped hercynite.
The copyrights for articles in this journal are retained by the author(s), with first publication rights granted to the journal. By virtue of their appearance in this open-access journal, articles are free to use with proper attribution in educational and other non-commercial settings.