添加硫酸铵的氢氧化物先驱体制备Y_2O_3纳米粉热分解动力学

Kinetics of thermal fecomposition of the hydrate precursor fispersed with (NH_4)_2SO_4 for synthesizing Y_2O_3 nanopowders

采用TG-DSC分析方法,研究了添加硫酸铵分散剂的氢氧化物先驱体制备Y2O3纳米粉热分解反应动力学。分别用Flynn-Wall-Ozawa法和Satava-Sestak法处理了不同升温速率下的TG-DSC曲线,两种方法得到的热分解反应动力学参数非常接近。先驱体的热分解过程为:Y2(OH)5NO3.nH2O→Y2(OH)5NO3→Y2O2(OH)NO3→Y2O3→脱出吸附的SO42-,计算所得的活化能分别为13.42、57.90、132.08和137.56kJ/mol,并推断了各阶段的反应动力学模型和最可机理函数。研究表明热分解各阶段分别符合Mampel Power法则,Avrami-Erofee方程,Avrami-Erofee方程和Mampel Power法则,相对应的机理为随机成核和随后生长。

Based on TG-DSC experiment, the kinetics of thermal decomposition of the hydrate precursor with （NH4）2SO4 dispersant for synthesizing Y2O3 nanopowders were investigated. The Flynn-Wall-Ozawa integral method and the Satava-Sestak integral method were used respectively to analyze the TG-DSC curves of the pre- cursor at different heating rates,and the two methods gave quite similar calculated results of kinetic parameters. The decomposition process of the precursor can be expressed as Y2 （OH）5 NO3 · nH2O→Y2 （OH）5 NO3→Y2O2 （OH）NO3→Y2O3→ release of absorbed SO4^2-. The calculated activation energies are 13.42, 57.90, 132.08 and 137.56kJ/mol, and the reaction mechanisms accords with mampel power principle, Avrami-Erofee function, Avrami-Erofee function and mampel power principle, respectively for the four stages. The corresponding reaction mechanisms are random nucleation and growth.