Browsing by Author "Kaczmarek, W.A."

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    A Mössbauer effect study of barium ferrite ball-milled in air
    (Hyperfine Interactions, 1994) Jayasuriya, K.D.; Kaczmarek, W.A.; Wu, E.; Campbell, S.J.
    The effects of dry-milling BaFe12O19 in air for periods of 190, 360, 590, 690 and 1000 h have been investigated by X-ray diffraction and M�ssbauer effect measurements. The sizes of the BaFe12O19 particles decrease on milling, as expected, although a partial decomposition of BaFe12O19 to ?-Fe2O3 is found to take place on extended milling (1000 h). The room temperature M�ssbauer spectra are consistent with superparamagnetic relaxation associated with the fine BaFe12O19 and ?-Fe2O3 particles. The X-ray diffraction patterns of all the milled samples exhibit features indicative of a disordered structural state, consistent with the nanoscale particles and a nanostructured state.
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    Surfactant assisted ball-milling of barium ferrite
    (IEEE Transactions on Magnetics, 1994) Jayasuriya, K.D.; Wu, E.; Kaczmarek, W.A.; Campbell, S.J.
    The effects of wet-milling barium ferrite in the presence of cationic or anionic surface active substances have been investigated by X-ray diffraction and Mossbauer spectroscopy measurements. Evidence for superparamagnetic relaxation of fine particles, both in the surfactant assisted ball-milled samples and in samples dry-milled in air is obtained from the room temperature and 4.2 K Mossbauer spectra. The similarity between samples milled at pH 3 with the cationic or anionic surfactants is due to electrostatic interactions of the surfactants' hydrocarbon groups with the positively charged barium ferrite surface