Structure evolution and thermal stability of La_2O_3-doped mullite fibers via sol-gel method

作     者：王炜 翁端 吴晓东 

作者机构：State Key Laboratory of New Ceramics&Fine ProcessDepartment of Materials Science and EngineeringTsinghua University The Second Artillery NCO Academy of PLA 

出 版 物：《Journal of Rare Earths》 (稀土学报（英文版）)

年 卷 期：2012年第30卷第2期

页      面：175-180页

核心收录：

学科分类：08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 

基　　金：Project supported by the Ministry of Science and Technology of China (2009AA064801) 

主　　题：mullite fibers lanthana doping phase transformation grain growth rare earths 

摘      要：The lanthana-doped mullite fibers were prepared via a sol-gel method from the aluminum isopropoxide-aluminum nitrate-tetraethyl orthosilicate system. The structure evolution and thermal stability of the mullite fibers were investigated by means of X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectroscopy, differential scanning calorimetry （DSC）, scanning electron microscopy （SEM） and trans-mission electron microscopy （TEM）. The results showed that the fibers obtained after calcination at 1000℃ was in the form of Al2O3-rich mullite, which tended to transform to stoichiometric mullite with the lanthana content increasing. The lattice parameter a exhibited a decline trend with the lanthana content increasing, while b showed an upward tendency. Correspondingly, the redshift of Si-O-Si bond from 1255 to 1245 cm-1 was observed. The grain growth was inhibited for the doped fibers, among which the 5% La2O3-doped sample presented a mini-mum crystallite size （17.2 nm） after calcination at 1000 ℃ for 1 h.