Investigation of preliminary evidence that Ga, Sc, and In influence the bulk and dynamic magnetic properties of hexagonal ferrites by means other than those supported in existing models has been undertaken. In SrFe 12Ϫx M x O 19 ͑MϭGa, In͒ and BaFe 12Ϫx Sc x O 19 , the predominant 12k sublattice exhibits a remarkable splitting into two distinct subpatterns, 12k 1 and 12k 2 : At xϭ0.3, hyperfine fields, H eff for 12k 1 are 411, 408, and 405 kOe, respectively, and for 12k 2 are 358, 339, and 311 kOe, respectively. The 12k 1 hyperfine field values are virtually unchanged from that of the pure hexagonal ferrites and are independent of substitution level. Contrastingly, the abruptness of the drop in the 12k 2 hyperfine field and its dependence on the nature of the substituting cation are remarkable. The relative intensity of the 12k 2 component correlates with the concentration of nonmagnetic species on the 2b and 4 f 2 sites and with the magnetic anisotropy. Scandium seems to have a more profound influence on the magnetic structure and interactions than indium or gallium. Further, at technically significant substitution levels, H eff of the different sublattices exhibit broad and overlapping distributions of values far removed from their distinctiveness in the pure hexaferrites. Thus, the net magnetization of Ga, Sc, and In-doped hexaferrites results from a complex interplay of magnetic dilution on the 2b site, enhancement of the magnetization through substitutions on the 4 f 2 site, and a complex influence from the substitution-induced 12k 2 sublattice.
Confirmation of the suggestion of B site zn2+ in nanocrystalline ZnFe204 has heen sought through X-ray diffraction, 5 7~e Miissbauer spectroscopy, magnetic susceptibility and TEM measurements on bulk and nanocrystalline samples prepared by different techniques. Measurements on bulk samples are in agreement with previously reported ones. Samples prepared at low temperature from solutions of salts exhibit broadened XRD patterns, susceptibilities 4-5 times that of bulk samples, broadened Mossbauer spectra and particle sizes between 5-20nm. Low-impact, ball-milled bulk samples exhibited properties similar to the low temperature, nanocrystalline samples. At 298K, the Mossbauer spectra exhibit no magnetic hyperfine splitting and no evidence for a significant proportion of A site ~e~+ ions. The unusually high susceptibilities appear to result mainly from the decreased particle size and not from profound changes in the cation distribution of a well-defined, spinel structure.
Paecilomyces sp. TLi, a coal-solubilizing fungus, was shown to degrade organic sulfur-containing coal substructure compounds. Dibenzothiophene was degraded via a sulfur-oxidizing pathway to 2,2'-dihydroxybiphenyl. No further metabolism of that compound was observed. Ethyl phenyl sulfide and diphenyl sulfide were degraded to the corresponding sulfones. A variety of products were formed from dibenzyl sulfide, presumably via free radical intermediates. Diphenyl disulfide and dibenzyl disulfide were cleaved to the corresponding thiols and other single-ring products. It was concluded that degradation of organic sulfur compounds by Paecilomyces involves an oxidative attack localized at the sulfur atom.
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