微乳液法合成La_(2)Ce_(2)O_(7)纳米粉体及其烧结性能的研究  

Microemulsion Synthesis of La_(2)Ce_(2)O_(7) Nano-Powder and Its Sintering Behavior

作　　者：姚邦 徐鹏飞 刘畅 黎家瑞 吕娅欣 王青春[1] 郜建全[1] Yao Bang;Xu Pengfei;Liu Chang;Li Jiarui;LüYaxin;Wang Qingchun;Gao Jianquan(School of Materials and Metallurgy,Inner Mongolia University of Science and Technology,Advanced Ceramics and Devices Laboratory,Inner Mongolia University of Science and Technology,Baotou 014010,China)

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古科技大学先进陶瓷与器件实验室,内蒙古包头014010

出　　处：《中国稀土学报》2023年第5期912-920,I0002,共10页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金项目(51704172)资助。

摘　　要：La_(2)Ce_(2)O_(7)由于具有良好的高温稳定性与化学稳定性等特点,在固体电解质,热障涂层及催化等领域具有广阔的应用前景。本文开发了一种新的微乳体系,即以油酸和2-氨基-2-甲基-1-丙醇(AMP)/正辛醇/煤油/水溶液组成的反相微乳液体系为反应介质,以六水合硝酸铈、六水合硝酸镧和草酸铵为原料,成功合成La_(2)Ce_(2)O_(7)前驱体纳米粉体。利用X射线衍射(XRD)、拉曼光谱(Raman)、热重-差示扫描量热(TG/DSC)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等多种表征手段分别对产物的物相结构、微观组织及烧结特性进行了综合表征与分析。结果表明:La_(2)Ce_(2)O_(7)前驱体经过700℃低温焙烧,迅速转化为La2Ce2O7纳米粉体,其平均晶粒尺寸在8~10 nm之间。XRD和Raman分析证实,粉体在700~1400℃范围内焙烧,物相结构仍为缺陷萤石相,说明该纳米粉体具有良好的高温稳定性。通过不同温度焙烧得到的平均晶粒尺寸与温度的Arrhenius关系,计算出La_(2)Ce_(2)O_(7)纳米粉体在800~1100℃范围内晶粒生长表观活化能为35.53 k J·mol^(-1),表明该超细纳米粉体具有优异的烧结活性。为进一步研究该纳米粉体的烧结性能,将La_(2)Ce_(2)O_(7)纳米粉末压制成片,分别经1400和1600℃煅烧6 h后,其微观组织形貌随温度的变化规律如下:1400℃时,其结构中含有大量的孔,晶粒尺寸约2μm,相对密度仅为85.38%;1600℃时,在烧结体的晶界与晶粒内部几乎不存在孔,相对密度达到97.82%。Due to its good high temperature stability and chemical stability,La 2 Ce 2 O 7 has wide application in the field of solid electrolytes,thermal barrier coatings and catalysis.This paper developed a novel microemul⁃sion system composed of oleic acid and 2-amino-2-methyl-1-propanol(AMP)/n-octanol/kerosene/aqueous solu⁃tion as the reaction medium,in which La 2 Ce 2 O 7 nanopowder precursor was successfully systhesized by use of ce⁃rium nitrate hexahydrate,lanthanum nitrate hexahydrate and ammonium oxalate as raw materials.By combina⁃tion of X-ray diffraction(XRD),Raman spectroscopy,thermogravimetric-differential scanning calorimetry(TG/DSC),transmission electron microscopy(TEM)and scanning electron microscopy(SEM),phase structure,mi⁃crostructure and sintering behaviors were systematically characterized and analyzed in details.The results reveal that La_(2)Ce_(2)O_(7) nanopowder precursor is rapidly transformed to La_(2)Ce_(2)O_(7) nanopowder with the average size of 8~10 nm after calcinations at 700℃.The analysis of XRD and Raman spectra confirmes that phase structures maintain defective fluorite structures in rhe temperature range of 700-1400℃,which indicates that the obtained nanopowder possesses outstanding high temperature stability.Through the Arrhenius relationship between the av⁃erage grain size and temperature obtained by calcination at different temperatures,the apparent activation energy of the grain growth of La_(2)Ce_(2)O_(7) nanopowders in the range of 800-1100℃ was calculated to be 35.53 kJ·mol^(-1),indicating that the super the fine nanopowder has excellent sintering activity.For further investigaton of sintering property,La_(2)Ce_(2)O_(7) nanopowder was compacted and calcined at 1400℃ for 6 h and 1600℃ for 6 h,respective⁃ly.The change rules of microstructures with temperature are observed as follows:At 1400℃,the as-sintered body contains lots of pores,crystallite size is 2μm and relative density is only 85.38%.At 1600℃,the pores are absent at grain boundary and intra-gra

关 键 词：微乳液法 纳米粉体 陶瓷 烧结性 稀土 

分 类 号：TQ129[化学工程—无机化工]