摘要
采用超声波辅助溶胶–凝胶法合成了铁酸镧（LaFeO3）纳米粉体,研究了超声波辅助处理时间对LaFeO3干凝胶热行为的影响。结果表明：当最佳超声波辅助处理时间为40 min时,形成LaFeO3晶相的烧结温度可以降至500℃,且产物的平均晶粒尺寸最小为18.65 nm,原因是超声波产生的超声空化气泡的爆裂所产生的瞬时高温和高压有助于降低形成LaFeO3胶核的临界形核功以及临界胶核半径,获得更多致密细小的LaFeO3胶核,促使胶核中的硝酸根离子能在更低的温度下快速完全分解,进一步促进柠檬酸的氧化燃烧分解,有效提高了LaFeO3干凝胶室温到172℃的质量损失速率,加速了LaFeO3晶核的形成。光催化结果表明,超声波辅助处理可以将LaFeO3产物光催化降解甲基橙的速率提高1倍。
LaFeO3 composite oxide was prepared via an ultrasound-assisted sol-gel method. The influence of ultrasound treatment time on the thermal behavior of LaFeO3 xerogel was analyzed. After 40-min ultrasound treatment, the formation temperature of LaFeO3 can be decreased to 500 ℃ with an average crystalline size of 18.65 nm. The instantaneous high temperature and high pressure generated from the burst of ultrasonic cavitation bubble can decrease the critical nucleation work and critical radius of LaFeO3 colloidal nucleus. The formation of more compact and dense LaFeO3 nuclei can make the existing NO3^- decomposition rapidly and completely at lower temperature, further promoting citric acid oxidized, combustion and decomposition. Thus, the weight loss rate of LaFeO3 xerogel from room temperature to 172 ℃ is improved with the quick formation of LaFeO3 at a lower temperature. Ultrasonic assistance can prompt the photocatalytic activity of the as-prepared LaFeO3 with the photodegradation rate of methyl orange doubled.
作者
沈宏芳
李清明
王燕民
陆有军
严祥辉
张笑
SHEN Hongfang1,2, LI Qingming2, WANG Yanmin1, L U Youjun2, YAN Xianghui2, ZHANG Xiao2(1. School of Materials Science and Engineering, South China University of Technology, Guangzhou 5106401, China; 2. School of Materials Science and Engineering, North Minzu University, Yinchuan 750021, Chin)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2018年第3期402-412,共11页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金(21563001,21663001)
2017年北方民族大学重点科研项目(2017KJ03)
宁夏高等学校科研项目(NGY2015158)
宁夏自然科学基金(NZ16085)
关键词
超声波
溶胶–凝胶
铁酸镧
光催化
ultrasound
sol-gel method
lanthanum ferrite
visible-light excited photocatalysis
