并加共沉淀法合成钴钛取代M型钡铁氧体中的协同共沉淀效应和配位效应

Synergetic coprecipitation effect and coordination effect in the Co-dump coprecipitation process for synthesizing Co-Ti substituted barium M-type ferrite

采用金属腐蚀状态图(E pH图)、热力学计算和并加共沉淀实验研究了化学共沉淀过程中pH值对合成钴钛取代M型钡铁氧体BaCoTiFe10O19共沉淀反应的影响。结果发现,E pH图法和热力学计算方法得到的Fe3+、Ti4+、Co2+和Ba2+离子理想完全共沉淀的最小pH值分别为9和7.9,而并加共沉淀实验表明在900℃煅烧共沉淀物2h的条件下形成单相BaCoTiFe10O19需要的实际最小pH值为8.5。这3种不同结果的产生原因可用并加共沉淀法合成钴钛取代M型钡铁氧体的共沉淀反应中同时存在阳离子的协同共沉淀效应和阴离子的配位效应解释。

The chemical coprecipitation process for synthesizing BaCoTiFe10O19 ultrafine powders has been investigated by means of corrosion versus pH plot (E-pH plot) for metal element, thermodynamic calculation and co-dump coprecipitation experimentation. The results show that the theoretical pH values of complete coprecipitation of all Fe3+, Ti4+, Co2+ and Ba2+ cations were in 9&lepH&le12.2 obtained by E-pH plot and pH≥7.9 obtained by thermodynamic calculation, respectively. The co-dump coprecipitation experiments indicate that the minimum pH value necessary to the formation of single-phase BaCoTiFe10O19 under 900°C for 2 h was pH=8.5. It was suggested that three different results and their dependency originate from both synergetic coprecipitation effect of cations and coordination effect of Cl- anions.