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Title: Role of nanocrystallinity on the chemical ordering of Co xPt 100-x nanocrystals synthesized by wet chemistry

Co xPt 100–x nanoalloys have been synthesized by two different chemical processes either at high or at low temperature. Their physical properties and the order/disorder phase transition induced by annealing have been investigated depending on the route of synthesis. It is demonstrated that the chemical synthesis at high temperature allows stabilization of the fcc structure of the native nanoalloys while the soft chemical approach yields mainly poly or non crystalline structure. As a result the approach of the order/disorder phase transition is strongly modified as observed by high-resolution transmission electron microscopy (HR-TEM) studies performed during in situ annealing of the different nanoalloys. The control of the nanocrystallinity leads to significant decrease in the chemical ordering temperature as the ordered structure is observed at temperatures as low as 420 °C. Furthermore, this in turn preserves the individual nanocrystals and prevents their coalescence usually observed during the annealing necessary for the transition to an ordered phase.
 [1] ;  [2] ;  [2] ;  [2] ;  [1] ;  [2]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Sorbonne Univ., Paris (France); CNRS, Paris (France)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1463-9076; PPCPFQ; KC0403020
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 17; Journal Issue: 42; Journal ID: ISSN 1463-9076
Royal Society of Chemistry
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; phase transitions; CoPt; in situ electron microscopy; Center for Functional Nanomaterials