以乙二胺四乙酸柠檬酸+乙二醇为复合络合剂, 冷冻干燥去除溶胶中水分, 提高凝胶中金属离子与氧化剂的分布均匀性, 并利用微波辅助溶胶凝胶自燃烧一步合成了六角铁酸钡纳米晶. 所得纳米晶近于球形, 尺寸在50～100nm, 其饱和磁化强度为338.5kA/m, 矫顽场仅为20.7kA/m. 分析表明, 富氧条件有利于避免自燃烧过程中由于有机物还原引起的铁元素分布不均匀, 从而有利于铁酸钡的相形成.
Single phase barium hexaferrite nanocrystals were innovatively one-step synthesized via a microwave-assisted sol-gel auto-combustion method using citric acid and ethylene diamine tetraacetic acid as composite chelating agents, and freeze-drying technique was used to remove sols' moisture that effectively improve the spatial distribution homogeneity of metal ions and oxidant in the gels. The obtained barium hexaferrite nanocrystals is characterized by fluffy particle aggregates with the diameter ranging from 50nm to 100nm. The nanocrystals contain single magnetic domains with a low coercive field of 20.7kA/m and a high saturation magnetization of 338.5kA/m. The analysis shows that keeping rich oxidant in the auto-combustion process can prohibit the reduction of iron ions by the organic fragment from the decomposition of fuels and promote the phase formation of barium hexaferrite.
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