(La_(1-2x)Sm_(x)Nd_(x))_(2)AlTaO_(7)氧化物的热物理性能  

Thermophysical Performances of (La_(1-2x)Sm_(x)Nd_(x))_(2)AlTaO_(7) Oxides

作　　者：冉书明[1] RAN Shuming(School of Intelligent Manufacturing,Chongqing Water Resources and Electrical Engineering College,Chongqing 402160,China)

机构地区：[1]重庆水利电力职业技术学院,智能制造学院,重庆402160

出　　处：《中国陶瓷》2022年第1期43-48,共6页China Ceramics

基　　金：重庆市教科委科学技术研究项目(KJZD-K201903801)。

摘　　要：以高纯度La_(2)O_(3)、Sm_(2)O_(3)、Nd_(2)O_(3)、Al_(2)O_(3)和Ta_(2)O_(5)为原材料,采用多步高温固相烧结法制备了(La_(1-2x)Sm_(x)Nd_(x))_(2)AlTaO_(7)陶瓷材料。对其相组成、显微形貌、元素组成物理性能进行了研究。结果表明,试验合成的氧化物具有单一的氟铝镁钠石结构。其显微组织结构致密,晶界清晰,元素种类和摩尔比与各自的化学式基本一致。由于掺杂增加了声子的散射程度,该类氧化物的热导率明显低于La_(2)AlTaO_(7),但由于Sm^(3+)和Nd^(3+)的引入降低了氧化物的容许系数,使得(La_(0.6)Sm_(0.2)Nd_(0.2))_(2)AlTaO_(7)的热导率略大于(La_(0.6)Sm_(0.1)Nd_(0.1))_(2)AlTaO_(7)。由于掺杂离子较低的半径,其热膨胀系数相比La_(2)AlTaO_(7)明显降低,而掺杂离子较高的电负性,使得(La_(0.6)Sm_(0.2)Nd_(0.2))_(2)AlTaO_(7)的热膨胀系数略大于(La_(0.8)Sm_(0.1)Nd_(0.1))_(2)AlTaO_(7)。该类氧化物的热导率和热膨胀系数满足热障涂层的要求。Using La_(2)O_(3),Sm_(2)O_(3),Nd_(2)O_(3),Al_(2)O_(3) and Ta_(2)O_(5) with high purity as raw reactants,the (La_(1-2x)Sm_(x)Nd_(x))_(2)AlTaO_(7) ceramics were synthesized adopting multi-step sintering at high temperatures,and the phaselattice,microstructure,element composition and thermophysical properties are investigated.Results showed that the obtained oxides exhibit single weberite crystal structure.The microstructure is very dense,and the interfaces among grains are very clean.The element composition and the corresponding mole ratio are consistent with the chemical-formula.Owing to the enhanced phonon scattering caused by doping cations,thermal conductivities of the obtained oxides are lower than that of La_(2)AlTaO_(7).However,the tolerance factor is reduced by addition of Sm^(3+)and Nd^(3+),which leads to the higher thermal conductivity of (La_(0.6)Sm_(0.2)Nd_(0.2))_(2)AlTaO_(7)than that of (La_(0.8)Sm_(0.1)Nd_(0.1))_(2)AlTaO_(7).Due to the low ionic radii of the doped cations,the thermal expansion coefficients of the obtained oxides are lower than that of La_(2)AlTaO_(7).Because of the relative high electro-negativities of the doped cations,thermal expansion coefficient of(La_(0.6)Sm_(0.2)Nd_(0.2))_(2)AlTaO_(7)is lower than that of (La_(0.8)Sm_(0.1)Nd_(0.1))_(2)AlTaO_(7).Thermal conductivities and expansion coefficients satisfy the requirements for thermal barrier coatings.

关 键 词：稀土钽铝酸盐 热障涂层 热导率 热膨胀系数 

分 类 号：TQ174.758.16[化学工程—陶瓷工业]