H. M. I. Abdallah

Structural and M?ssbauer studies of Mn0.5Co0.5Fe2O4 ferrites prepared by high energy ball milling and glycolthermal methods

We have investigated the properties of three Mn0.5Co0.5Fe2O4 ferrites synthesized directly from high purity metal oxides (Sample A) and from MnFe2O4 and CoFe2O4 ferrites (Sample B) by mechanical milling and by glycolthermal process (Sample C). XRD results show essentially single phase spinel structure. Sample C is the best sample followed by Sample B based on the presence of minor impurity peaks near 2? ? 38? and 52?. More impurity peaks appear to grow after annealing above 400 ?C. Samples A and B have been found to have similar Fe-57 M?ssbauer spectra before and after annealing at 1050 ?C. The spectrum for each sample changes significantly after annealing. This is attributed to changes of both grain sizes and impurity phases with thermal annealing. At least two sextets and two doublets are used to fit the M?ssbauer spectra.

Tetracycline-ferrite nanocomposites formed via high-energy ball milling and the influence of milling conditions

High-energy ball milling was used to mediate the formation of nanocomposites containing tetracycline and magnetic nanoparticles. Tetracycline-HCl was ball milled for 1, 3, 5, 15, and 30 h under argon or air atmosphere with preformed Mg 0.5 Zn 0.5 Fe2O4 nanoferrites prepared by glycolthermal method. The structural, thermal, and magnetic properties of these novel materials and the effect of milling atmosphere on composition, crystallinity and cation distribution were then characterized by ICP-OES, DSC/TGA, XRPD, ATR-IR, UV-Vis and Mössbauer spectroscopy. Tetracycline underwent rapid and consecutive metal coordination events in the milling process to yield complexes characterized by bathochromic shifts in its electronic spectra and suppression of electronic absorbance at 365 nm. Changes in stretching vibrations due to the A-ring carbonyl (1616 cm(-1)), amide II nitrogen (1602 cm(-1)), and CO bond (1039 cm(-1)) indicate Mg-type interactions imposed on the metals. Exothermic oxidation of the drug at 235°C disappeared after 5h milling with the nanoferrites, and the composites formed remained thermostable up to 500°C. Tetracycline-nanoferrites (Tet-NF) are magnetic-ordered materials with a well-defined spinel-type structure. Analysis of the Mössbauer data suggests that the milling time and atmosphere have significant influence on cation distributions in Tet-NF composites.