Au/Pt和Au/Ag两种合金系纳米颗粒合金化的热力学与动力学研究

项目名称： Au/Pt和Au/Ag两种合金系纳米颗粒合金化的热力学与动力学研究

项目编号： No.50801024

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 武器工业

项目作者： 肖时芳

作者单位： 湖南大学

项目金额： 22万元

中文摘要： 合金纳米颗粒以其优异的物理与化学性能而受到普遍关注。纳米颗粒的高比表面率为合金化过程提供了强的驱动力，纳米尺度下合金化行为的研究有助于对合金纳米颗粒的结构和性能进行调控。现有理论研究难以解释纳米颗粒合金化行为的多样性和复杂性。本项目拟以Au/Pt、Au/Ag 两个典型合金系为研究对象，通过计算合金纳米颗粒的形成焓随颗粒尺寸和组分的关系函数，从热力学的角度评估纳米体系的合金形成能力，应用嵌入原子模型结合分子动力学方法模拟"颗粒-颗粒"烧结过程中的合金化、原子沉积于颗粒表面之后的合金化、核-壳结构合金化三种情况下原子的运动规律和颗粒微观结构的演变，揭示颗粒结构、尺寸、成分和外界温度对纳米颗粒合金化行为的影响，可望探讨纳米颗粒合金化机制，为改进和优化合金纳米颗粒的制备工艺及开发新型合金提供理论指导。

中文关键词： 纳米颗粒；合金化；形成焓；分子动力学模拟

英文摘要： Alloy nanoparticles have attracted a lot of interest for their outstanding physical and chemical properties. As a result of high surface-to-volume ratio, the nanoparticles exhibit enhanced alloying ability. The recognition of alloying behavior on a nanosacle is help to control the structure and properties of alloy nanoparticles during material design. However, affected by the diversity and complexity of alloying process, the existing theoretic investigation is insufficient to well explain alloying behavior. The project aims to evaluate alloying ability from the viewpoint of thermodynamics by analyzing the variation of enthalpy of formation with the size and composition of two types of typical nanoparticles (Au/Pt and Au/Ag), and reveal the effect of the size and composition of particles and ambient temperature on alloying behavior from the viewpoint of kinetics by simulating the evolution of microstructure of nanoparticle and tracing the process of atomic movement in the course of sintering of heterogeneous nanoparticles, depositing of atoms on a nanoparticle matrix and heating up core-shell nanoparticles with molecular dynamics and embedded atom method. These studies are promising to interpret alloying mechanism and provide theoretic guidance for improving the synthesis technics of alloy nanoparticles and the development of new type of alloy.

英文关键词： nanoparticle; alloying; enthalpy of formation; molecular dynamics