摘要
Fine nickel ferrite precursors NiFe2（C204）3·6H2O were obtained via co-precipitation method with low grade nickel matte as the raw material. Thermodynamic analysis of NiClz-FeC12-（NH4）2C204-H20 system for precipitation identified that the theoretical optimum co-precipitation pH value is 2, and C2O2 has strong complexation with Ni2＋ and Fe2＋ ions. Based on these theoretical considerations, the effects of parameters on the precipitation rates and precursors size were investigated systematically. The results show that the optimum co-precipitation conditions are pH=2, temperature 45 ℃, 1.2 times theoretical amount of （NH4）2C204 dosage and 3% PEG400 addition. Under these conditions, the precipitation rates of Ni2＋ and Fe2＋ are both over 99.8%, with the precursors size of 1-2 urn. Furthermore, X-ray diffraction （XRD） and thermogravimetry-differential thermal analysis （TG-DTA） demonstrate that the precursors are single-phase solid solution, wherein the nickel/iron atoms are replaced by the iron/nickel atoms reciprocally.
以低冰镍为原料,采用草酸盐共沉淀法合成颗粒细小的铁酸镍前躯体NiFe2(C2O4)3·6H2O。NiCl2-FeCl2-(NH4)2-C2O4-H2O体系的热力学研究表明:Ni2+和Fe2+的理论最佳共沉淀pH值为2,C2O2-4对Ni2+、Fe2+离子具有较强的络合作用。在理论研究的基础上,考察沉淀参数对沉淀率和前躯体粒度的影响。结果表明:最佳共沉淀条件为溶液pH=2,反应温度为45℃,(NH4)2C2O4加入量为理论值的1.2倍,PEG400加入量为3%。在此条件下,Ni2+和Fe2+的沉淀率达99.8%,所得前躯体的粒径为1～2 um。XRD和TG-DTA分析表明:所得前躯体为单相置换固溶体,反应过程中镍、铁原子相互取代。
基金
Project(2012BAB10B04) supported by National Key Technology R&D Program of China
Project supported by Hunan Provincial Innovation Foundation for Postgraduate,China
