稀土铝酸盐(RE4Al2O9)的研究现状与应用  

Progress and Prospective of Rare Earth Aluminates:RE4Al2O9

作　　者：孙亚男 赵小军[2] 周延春[1] SUN Yanan;ZHAO Xiaojun;ZHOU Yanchun(Advanced Functional Composite Laboratory,Aerospace Research Institute of Materials&Processing Technology,Beijing 100076,China;School of Materials Science and Engineering,Central South University,Changsha 410083,Hunan,China)

机构地区：[1]航天材料及工艺研究所先进功能复合材料技术重点实验室,北京100076 [2]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《陶瓷学报》2020年第3期317-333,共17页Journal of Ceramics

基　　金：国家自然科学基金(51672064,51972089)。

摘　　要：在RE2O3-Al2O3体系中,当RE2O3︰Al2O3=2︰1时,可生成分子式为RE4Al2O9的稀土铝酸盐(其中RE=La、Nd、Eu、Gd、Tb、Dy、Ho、Er、Yb、Lu和Y)。RE4Al2O9系列化合物具有相似的晶体结构,均属于单斜晶系,空间群为P21/c。在RE4Al2O9的结构中铝原子位于Al O4四面体中心,两个Al-O四面体共用顶角的一个氧原子构成Al2O7双四面体;四个稀土金属原子中有三个与O以七重配位的方式结合构成十面体,另外一个则与O以六重配位方式结合构成八面体。本文旨在总结RE4Al2O9的晶体结构、制备方法,并介绍其性能及在热障/环境障涂层、固态激光、生物荧光标记等领域的重要应用前景。RE4Al2O9的合成方法主要有固相反应法、溶胶凝胶法、共沉淀法、燃烧合成法等。通过X-射线衍射分析和Rietveld精修可获得其晶胞参数和原子位置等数据。采用第一性原理计算,可预测弹性模量、热导率、热膨胀系数等性能。在RE4Al2O9材料中,研究最为全面的是Y4Al2O9,计算和实验结果均表明,Y4Al2O9具有较低的热导率、良好的高温稳定性、低的杨氏模量和较高的损伤容限。对于Nd4Al2O9、Gd4Al2O9、Tb4Al2O9等的研究主要集中于热学性能,对Yb4Al2O9、La4Al2O9、Lu4Al2O9、Sm4Al2O9等的研究相对较少,它们的力学和热学性能有待探索。另外,RE4Al2O9在升降温过程中会出现相变引起的体积变化,且变化可逆,该可逆过程对应相的具体成分和相变过程仍然未知。With RE2O3︰Al2O3=2︰1,single phase RE4Al2O9(RE=La,Nd,Eu,Gd,Tb,Dy,Ho,Er,Yb,Lu and Y)can be formed in the RE2O3-Al2O3 system.These rare earth aluminates have isomorphous crystal structures.They all have monoclinic structure with the space group of P21/c.In RE4Al2O9,the Al atoms are coordinated by four O atoms,forming Al O4 tetrahedra,while two of them share an apical O atom to form the Al2O7 group.For RE,three of them are 7-coordinated by O,forming RE-O decahedra,whereas the other one is 6-coordinated by O,forming RE-O octahedra.This article is aimed to summarize the progress in synthesis,crystal structures,properties and applications of RE4Al2O9 in the areas of thermal/environmental barrier coatings,solid-state lasers,bioluminescence labeling and so on.The main methods to synthesize RE4Al2O9 powders include solid state reaction,sol-gel,co-precipitation and combustion.The lattice parameters and atomic positions can be obtained by using X-ray diffraction(XRD)and Rietveld refinement.Meanwhile,elastic modulus,thermal conductivity,thermal expansion coefficient can be predicted through first-principles calculations.Among various RE4Al2O9 aluminates,Y4Al2O9 has been studied most comprehensively.Both theoretical prediction and experimental results demonstrate that Y4Al2O9 has low thermal conductivity,high temperature stability,low Young’s modulus and strong damage tolerance.Nd4Al2O9,Gd4Al2O9 and Tb4Al2O9 are mainly studied in terms of their thermal and mechanical properties,while very few works have been carried out on Yb4Al2O9,La4Al2O9,Lu4Al2O9 and Sm4Al2O9.In addition,RE4Al2O9 usually experiences reversible phase transitions with volume shrinkages during heating and cooling.However,details of the phase transition process are still remained to be clarified.

关 键 词：稀土铝酸盐 单斜晶系 第一性原理计算 力学性能 热学性能 

分 类 号：TQ174.75[化学工程—陶瓷工业]