化学共沉淀法制备NiCuZn铁氧体前驱体的热力学分析

THERMODYNAMIC ANALYSIS ON PREPARATION OF NiCuZn FERRITE PRECURSOR BY CO-PRECIPITATION METHOD

对于用化学共沉淀法制备NiCuZn铁氧体前躯体,确定反应体系的共沉淀区域是确保铁氧体组分准确且性能优良的关键。通过对Me-NaOH-H_2O(Me=Fe,Ni,Cu,Zn)以及Me-NH_4HCO_3-NH_3-H_2O体系的热力学分析,得到各金属离子浓度[Me^(2+)]与pH值的关系,确定了体系的完全共沉淀区域。热力学分析表明:在Me-NaOH-H_2O体系中.当pH=10～11时,各金属离子可完全共沉淀。在Me-NH_4HCO_3-NH_3-H_2O体系中,Ni^(2+),Cu^(2+),Zn^(2+)这3种离子和NH_3的络合能力很强,在含有NH_3的体系中很难实现共沉淀。以NaOH为沉淀剂。pH=10.5的条件下,用氢氧化物共沉淀法制备出了颗粒细小,粒度均匀的NiCuZn铁氧体前驱体微粉。

For NiCuZn ferrites prepared via chemical co-precipitation method,determination of the co-precipitation window for sev- eral Men^(n+)ions(Me^(n+)refers to Fe^(2+),Ni^(2+),Cu^(2+),Zn^(2+),etc.)is the key to ensure the desired composition and high magnetic performance. Through thermodynamic analysis for different Me^(n+)ions in NaOH-H_2O and NH_4HCO_3-NH_3-H_2O systems,the[Me^(n+)]concentration as a function of pH value was obtained,and hence the pH window of complete co-precipitation for various Me^(n+)ions ...