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Title: Effects of Ag addition on FePt L1{sub 0} ordering transition: A direct observation of ordering transition and Ag segregation in FePtAg alloy films

FePt and (FePt){sub 91.2}Ag{sub 8.8} alloy films were deposited by magnetron sputtering. The average coercivity of (FePt){sub 91.2}Ag{sub 8.8} films reaches 8.51 × 10{sup 5} A/m, which is 0.63 × 10{sup 5} A/m higher than that of the corresponding FePt films. Ag addition effectively promotes the FePt L1{sub 0} ordering transition at a relatively low annealing temperature of 400 °C. The promotion mechanism was investigated by using in situ high-resolution transmission electron microscopy (HRTEM) and ex situ X-ray absorption fine structure (XAFS). The concurrence of ordering transition and Ag segregation in FePtAg alloy films was first observed by using in situ heating HRTEM. The time-resolved evolution reveals more details on the role of Ag addition in FePt low-temperature ordering. Ex situ XAFS results further confirm that Ag replaces Fe sites in the as-deposited films and segregates from FePt-Ag solid solution phase through annealing at elevated temperatures. The segregation of Ag atoms leaves vacancies in the grain. The vacancy formation is believed to accelerate the diffusion of Fe and Pt atoms, which is critical for the L1{sub 0} ordering transition.
Authors:
;  [1] ;  [2]
  1. School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)
  2. Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1, Oh-okayama, Meguro-ku, Tokyo 152-8552 (Japan)
Publication Date:
OSTI Identifier:
22493073
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; COERCIVE FORCE; FINE STRUCTURE; IRON ALLOYS; MAGNETRONS; PLATINUM ALLOYS; SEGREGATION; SILVER; SILVER ALLOYS; SOLID SOLUTIONS; SPUTTERING; TEMPERATURE RANGE 0065-0273 K; THIN FILMS; TIME RESOLUTION; TRANSMISSION ELECTRON MICROSCOPY; VACANCIES; X-RAY SPECTROSCOPY