本研究以Ce(NO_3)_3·6H_2O和Sm_2O_3为主要原料,采用共沉淀-喷雾干燥法制备出Sm_2O_3掺杂CeO_2(SDC)的纳米粉末.通过对制得粉体进行DSC-TG、XRD、SEM等表征,研究了SDC纳米晶在煅烧过程中的晶体生长动力学.结果表明:400℃以下,煅烧时间对SDC晶粒尺寸的影响很小,随着温度的升高,其影响逐渐增大,800℃时,煅烧时间对晶粒尺寸的影响很大;但随着煅烧温度的提高,其影响又逐渐减小,在1000℃时,晶粒粒径随着煅烧时间的延长,不再发生变化.根据晶体生长动力学方程,SDC的晶体生长机制在不同温度条件下存在一定差异,在低温下(300-400℃),界面反应占主导;中温下(500℃左右),纳米效应、界面反应与扩散传质的共同作用;高温下(600-800℃),体现为扩散传质.
The Sm_2O_3-doped CeO_2 (SDC) nano-powders were prepared by co-precipitation and spray of the SDC powders were characterized by XRD, and the particle size and shape were observed by SEM. The influence of sintering process on the particle size was discussed, and the grain growth dynamics in sintering process was studied. The results showed that the size of crystallite kept steadily with increasing sintering time blew 400℃. Between 400 and 800℃, the size of crystallite increased rapidly with increasuing sintering time. But the influence of sintering time on the particle size diminishes gradually with further increasing the sintering time. That was constant at 1000℃. According to grain growth exponent, the main factors of the growth mechanism were interracial reaction, nanostructural effects and diffusion mass transfer, and diffusion mass transfer, respectively, at below 300-400℃, about 500℃ and 600-800℃.
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