In situ transmission electron microscopy and scanning transmission electron microscopy studies of sintering of Ag and Pt nanoparticles

被引：66

作者：

Asoro, M. A. ^{[1
]}

Ferreira, P. J. ^{[1
,2
]}

Kovar, D. ^{[1
,2
]}

机构：

[1] Univ Texas Austin, Mat Sci & Engn Program, Austin, TX 78712 USA

[2] Univ Texas Austin, Dept Mech Engn, Austin, TX 78712 USA

来源：

ACTA MATERIALIA | 2014年 / 81卷

基金：

美国国家科学基金会;

关键词：

Microscopy; Diffusion; Kinetics; Coarsening; Densification; SURFACE SELF-DIFFUSION; GROWTH-KINETICS; SILVER; CATALYST; TEMPERATURE; COALESCENCE; PLATINUM; MECHANISMS; PARTICLES; GRAPHITE;

D O I：

10.1016/j.actamat.2014.08.028

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Transmission electron microscopy and scanning transmission electron microscopy studies were conducted in situ on 2-5 nm Pt and 10-40 nm Ag nanoparticles to study mechanisms for sintering and to measure relevant sintering kinetics in nanoscale particles. Sintering between two separated particles was observed to initiate by either (1) diffusion of the particles on the sample support or (2) diffusion of atoms or small clusters of atoms to the neck region between the two particles. After particle contact, the rate of sintering was controlled by atomic surface diffusivity. The surface diffusivity was determined as a function of particle size and temperature from experimental measurements of the rate of neck growth of the particles. The surface diffusivities did not show a strong size effect for the range of particle sizes that were studied. The surface diffusivity for Pt nanoparticles exhibited the expected Arrhenius temperature dependence and did not appear to be sensitive to the presence of surface contaminants. In contrast, the surface diffusivity for Ag nanoparticles was affected by the presence of impurities such as carbon. The diffusivities for Ag nanoparticles were consistent with previous measurements of bulk surface diffusivities for Ag in the presence of C, but were significantly slower than those obtained from pristine Ag. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：173 / 183

页数：11

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