埋嵌在超薄Al_2O_3薄膜中的Ni纳米颗粒在生长过程中的应变场分布

对于埋嵌在介电材料中的纳米颗粒,在其生长过程中总是不可避免的伴随着应变场的产生,而这种应变场会的分布对纳米颗粒的物理性能产生重要的影响.在本文中用脉冲激光沉积技术和快速退火成功地制备了埋嵌在超薄Al2O3薄膜中的Ni纳米颗粒.利用高分辨透射电子显微镜观察到立方形Ni纳米颗粒埋嵌在超薄Al2O3薄膜中.用有限元算法系统地模拟了Ni纳米颗粒生长过程中的应变场分布,研究工作发现,随着Ni纳米颗粒的生长,Ni纳米颗粒受到了非均匀偏应变作用逐渐增强,而且变得越来越不均匀,这种非均匀的偏应变作用对于纳米颗粒的微观结构有很大的影响.可以通过调节Ni纳米颗粒生长过程中的应变场来实现对Ni纳米颗粒界面态的调控,从而进一步优化Ni纳米颗粒的物理性能.系统地研究磁性Ni纳米材料的应变场分布,对有效的调控其物理化学性能有着非常重大的意义.

Strain distribution of Ni nanoparticles embedded in Al2O3 ultrathin film

Nucleation and growth lead to substantial strain in nanoparticles embedded in a host dielectrics matrix. The distribution of strain field plays an important role in the physical properties of nanoparticles. Ni nanoparticles embedded in the amorphous AlcOa ultrathin films were fabricated by using pulsed laser deposition and rapid thermal annealing. The results from high-resolution transmission electron microscope also revealed that the complete isolation of Ni nanoparticles with cubic shape embedded in ultrathin amorphous A1203 matrix. The growth strain of Ni nanoparticle embedded in the A1203 matrix was investigated. Finite element calculations clearly indicate that the Ni nanoparticle incurs a net deviatoric strain. With the growth of Ni nanoparticle, the larger Ni nanoparticles incur stronger net deviatoric strain and the strain become more and more nonuniform, which will have much influence on the structure and morphology of Ni nanoparticles. Strain engineering is an effective tool for tailoring the properties of Ni nanoparticles.