基底材料对嵌入型Fe3O4纳米颗粒的应变场影响
The Effect of Substrate Material on the Strain Field of Embedded Fe3O4 Nanoparticles

埋嵌型纳米颗粒在生长的过程中会受到周围基质材料对其施加的应力作用,应力的大小不仅会对纳米颗粒的晶格结构和物理性能产生影响,还与纳米颗粒的尺寸大小息息相关.因此,研究埋嵌在不同薄膜材料中的纳米颗粒生长过程中的应变场分布对于调控纳米颗粒的物理性能有着重要的意义.该文利用脉冲激光沉积和快速退火技术成功地制备了分别镶嵌在非晶氧化铝薄膜、非晶氧化镥薄膜和非晶二氧化硅薄膜中的Fe3O4纳米颗粒,并利用透射电子显微镜观察这些球形纳米颗粒.为了研究纳米颗粒的尺寸与应力大小之间的关系,采用有限元算法分别模拟仿真了这些纳米颗粒的应变场分布,并对结果进行了系统的分析.研究发现:Fe3O4纳米颗粒在不同薄膜材料生长过程中均受到非均匀偏应变作用,而且纳米颗粒的尺寸及应变场分布与纳米颗粒周围基质材料的杨氏模量和泊松比密切相关.在不同基质材料中生长的纳米颗粒所受到的应变场分布也有所不同,这为调控纳米颗粒的晶格结构和形貌以及物理性能提供了一个新思路.
Embedded nanoparticles will be subjected to the stress imposed by surrounding matrix materials during their growth.The stress of nanoparticles is not only affect the lattice structure and physical properties of nanoparticles,but also closely related to the size of nanoparticles.So it is fundamentally nessary to study the strain distribution of nanoparticles embedded in different thin films.Fe3O4 nanoparticles embedded in the amorphous Al2O3,Lu2O3 and SiO2 matrix are fabricated by using pulsed laser deposition and rapid thermal annealing,respectively.The results from transmission electron microscope also reveal that the complete isolation of Fe3O4 nanoparticles embedded in amorphous these matrixs.In order to study the relationship between the size of nanoparticles and the size of stress,the strain field distribution of these nanoparticles is simulated by finite element method,and the results are analyzed systematically.Finite element calculations clearly indicate that the Fe3O4 nanoparticle incurs a net deviatoric strain.The size and strain field distribution of nanoparticles are closely related to Young's modulus and poisson's ratio of the materials around nanoparticles.The strain field distribution of nanoparticles grown in different matrix materials is also different,which provides a new idea for regulating the lattice structure,morphology and physical properties of nanoparticles