添加稀土元素对热障涂层YSZ陶瓷层晶格畸变的影响

Influence of Rare Earth Elements Additions in YSZ Ceramic Coatings of Thermal Barrier Coatings on Lattice Distortion

采用第一原理赝势平面波方法对添加稀土元素的二氧化锆晶胞进行了几何优化计算,对计算后的X-O键键长、晶格常数变化及键集居数进行了分析,并将计算结果与实验数据进行对比讨论。结果表明,添加稀土元素后,二氧化锆晶胞将发生膨胀畸变,X-O键键长变大,键集居数变小。这些变化引起晶格振动频率降低,声子散射加剧,从而使材料热扩散系数降低。此外,在一定范围内,稀土元素的共价半径越大,所引起的膨胀畸变也越大,键集居数越小,材料的热扩散系数也会更小。

Geometry optimization of zirconia added with rare earth elements is carried out by means of the first principle method based on plane-wave pseudopotential theory. X-O bond length, lattice constant, and atomic bond populations are analyzed. The calculation results are analyzed by comparing with the experiment data. It is found that with the addition of rare earth elements, expansion distortion occurres in zirconia crystal cell, the X-O bond length becomes longer and the bond population becomes smaller, which will increase the phonon dispersion and reduce the lattice vibrating frequency and the thermal diffusion coefficient. Within the range of covalent radium used for the calculation, the larger the covalent radium of the rare earth element, the larger the expansion distortion, and the smaller the population, which will be benefit for reducing the thermal diffusion coefficient.