共沉淀制备MnZn铁氧体前驱体粉的热力学分析

摘要

针对Me(Me =Fe2+、Mn2+、Zn2+ )-NaOH-H2O体系、Me-NaOH-Na2CO3-H2O体系以及Me-NH4HCO3-NH3·H2O-H2O体系,根据最新的热力学数据及离子在水溶液中的存在形式,进行了最新的热力学计算,得到了各金属离子[Me]T与pH值之间的关系,并给出了不同条件下的log[Me]T-pH曲线,从而确定3种金属离子的共沉淀范围.结果表明,在Me-NaOH-H2O体系中,控制pH值在10.0～10.7之间,可以让3种金属离子共沉淀；在Me-NH1 HCO3-NH3·H2O-H2O体系中.决定3种离子共沉淀范围的是Zn2+的完全沉淀范围,当[C]T=0.5mo1/L、[N]T =0.75mol/L时,控制pH值在6.0～7.5之间,可满足三者的共沉淀要求；在Me-NaOH-Na2CO3-H2O体系中,当[C]T =0.5mol/L时,控制反应体系的pH值在6.3～10.6之间,就可以保证3种金属离子共沉淀,从而获得成分准确的前驱体粉料.%XIA JingbAccording to the latest thermodynamic data, the thermodynamic analysis of different Me ions(Me= Fe2+ ,Mn2+ ,Zn+) on the system of Me-NaOH-H2O,Me-NaOH-Na2CO3-H2O and Me-NH, HCO3-NH3 · H2O-H2O was carried out. The relationship between the total concentration of Me and pH value was obtained, and the field of co-precipitation of Me was got at a suitable pH value. It shows that Fe2+ , Mn2+ and Zn2+ can co-precipitate in Me-NaOH-H2O system at the pH value of 10. 0-10. 7. In Me-NH4HCO3-NH3 · H2O-H2O system, when the pH value is 6. 0-7. 5, the total carbon concentration [C]T=0. 5mol/L and the total nitrogen concentration [N]T=0. 75mol/L, the three metal ions Me can co-precipitate completely. In order to obtain the precursor with accurate composition by co-precipitation in Me-NaOH-Na2CO3-H2O system with the total carbon concentration [C]T =0. 5mol/L,the pH value must be dominated between 6. 3 and 10. 6.