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Title: Size effect on order-disorder transition kinetics of FePt nanoparticles

The kinetics of order-disorder transition of FePt nanoparticles during high temperature annealing is theoretically investigated. A model is developed to address the influence of large surface to volume ratio of nanoparticles on both the thermodynamic and kinetic aspect of the ordering process; specifically, the nucleation and growth of L1{sub 0} ordered domain within disordered nanoparticles. The size- and shape-dependence of transition kinetics are quantitatively addressed by a revised Johnson-Mehl-Avrami equation that included corrections for deviations caused by the domination of surface nucleation in nanoscale systems and the non-negligible size of the ordered nuclei. Calculation results based on the model suggested that smaller nanoparticles are kinetically more active but thermodynamically less transformable. The major obstacle in obtaining completely ordered nanoparticles is the elimination of antiphase boundaries. The results also quantitatively confirmed the existence of a size-limit in ordering, beyond which, inducing order-disorder transitions through annealing is impossible. A good agreement is observed between theory, experiment, and computer simulation results.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3]
  1. School of Materials Science and Engineering, Central South University, Changsha 410083 (China)
  2. (China)
  3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)
Publication Date:
OSTI Identifier:
22255179
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANNEALING; COMPUTERIZED SIMULATION; KINETICS; NANOSTRUCTURES; NUCLEATION; ORDER-DISORDER TRANSFORMATIONS; PARTICLES