富铁铁酸钴的室温合成和Mossbauer表征

Synthesis and Mossbauer Characteristic of Cobalt Bearing Ferrite Particles

采用氧化-沉淀法在室温下合成了不同钴含量的铁酸盐.不同反应时间样品的IR和XRD谱图分析表明,富铁铁酸钴是通过中间体绿锈形成的.通过调节初始溶液中Co/Fe比(Co/Fe分别为:1/20、1/15、1/10、1/7、1/5、1/3)合成了钴含量分别为Co/Fe=0.05、0.06、0.08、0.12、0.17、0.18的富铁铁酸钴,并通过XRD和化学测定分析了上述铁酸盐的化学计量和结构,并结合Mossbauer谱进一步分析了产物形成的过程.实验结果表明:在室温条件下,随初始溶液中钴含量的增加,钴在尖晶石结构中占据八面体空隙中Fe3+的位置,且钴含量的增加不利于尖晶石结构的形成,游离于绿锈结构以外的钴的化合物中包含了非磁性Fe(Ⅲ)的氧化物.

Cobalt bearing magnetite particles were synthesized by aerial oxidation of ferrous and cobalt ions at alkaline condition and room temperature. The samples obtained at different intervals during reaction were characterized by XRD and IR. The cobalt-bearing ferrites were produced through the green-rust intermediate phase. Different compounds were synthesized by using Co^2＋/Fe^3＋ starting ratios of 1/20, 1/15, 1/10, 1/7, 1/5 and 1/3, and Co-ferrites with Co/Fe ratios of 0.05,0.06,0.08, 0.12, 0.17, 0.18 were obtained. The chemical composition and microstructure of those precipitates were characterized by chemical analysis and XRD. Meanwhile, further information of the producing process was confirmed by Mossbauer analysis. The results reveal that in the conditions of room temperature Co^2＋ will replace Fe^3＋ at octahedral positions in the spinel structure, and the increase of Co in initial solution is disadvantageous to the formation of the spinel structure. The non-magnetic ferric oxide is included in the compound containing Co outside the green-rust system.