正、反向共沉淀法对Pr_2Zr_2O_7纳米粒子表观活化能的影响

以氨水作为沉淀剂,采用正、反向共沉淀法制备Pr2Zr2O7纳米粒子。利用XRD、SEM、TEM、TG-DTA等测试手段表征了样品物相及形貌;研究其制备过程中合成动力学和晶粒生长动力学,采用Doyle-Ozawa法和Kissinger法分别计算正、反向沉淀粒子在主要反应阶段的表观活化能。结果表明:反向沉淀的滴定速率为2 mL·min-1、母盐溶液初始浓度0.05 mol·L-1、反应体系温度273 K、pH值11、煅烧温度为1 173 K,保温2 h的条件下获得的样品形貌近球形、无团聚现象、一次粒径约60 nm。Pr2Zr2O7前驱体的分解过程分为3个阶段,正、反向粒子各阶段平均表观活化能分别为:71.2、97.8、183.2 kJ·mol-1和45.37、84.34、152.16kJ·mol-1;晶粒生长活化能分别为19.02和11.95 kJ·mol-1,后者比前者的晶粒生长活化能降低了7.07 kJ·mol-1;反向共沉淀制备工艺优于正向共沉淀法。

Effect of the NSC and RSC Co-precipitation Methods on Apparent Activation Energy of Pr2Zr2O7 Nanopowders

The Pr₂Zr₂O₇ nanoparticles were prepared by using NSC and RSC co-precipitation method with ammonia as precipitant agent. XRD, SEM, TEM and TG-DTA were applied to analysis the crystallization and morphology of the samples. Synthesis kinetics of the preparation process and dynamics of grain growth were studied, and the apparent activation energy was calculated respectively by using Doyle-Ozawa method and the Kissinger method. The results show that the samples topography near spherical, there are no agglomeration and the mean particle size is about 60nm. They were obtained under the conditions of titration rate, 2 mL·min^-1, initial concentration of resolution, 0.05 mol·L^-1, system temperature 273K and calcination at 1173 K for 2 h by RSC. The average apparent activation energy of the particles, obtained by NSC, were 71.2, 97.8 and 183.2 kJ·mol^-1 in each stage and the RSCs were 45.37, 84.34 and 152.16 kJ·mol^-1; the grain growth activation energy of them were 19.02 and 11.95 kJ·mol^-1 respectively, the latter decreases 7.07 kJ·mol^-1 than the former. Reverse co-precipitation preparation technology is better than that of positive co-precipitation method.