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Title: High coercivity sized controlled cobalt–gold core–shell nano-crystals prepared by reverse microemulsion

Graphical abstract: - Highlights: • Calculating the crystallinity percentage and percentage of phases presented in Co–Au core–shell nanoparticles. • Magnetic properties of four groups nanogarin: 5, 10, 15, 20 nm. • Single domain ferromagnetic materials with high coercivity at room temperature. • Intrinsic blocking temperature measured in zero field cooled-warmed (ZFC-W). - Abstract: Size-controlled cobalt–gold core–shell nanoparticles were synthesized via the reverse-micelle microemulsion method. In order to control the size of the nanoparticles, the nucleation and growth process were performed within a confined space by adjusting the water to surfactant ratio of reverse micelles solution during synthesis. The crystallinity percentage and percentage of phases presented in Co–Au core–shell nanoparticles were calculated using X-ray diffraction data. The results from transmission electron microscopy provide direct evidence for core–shell structure nanomaterials. Magnetic properties of the samples were investigated using a vibrating sample magnetometer. The as-prepared samples showed significant coercivity at room temperature. The intrinsic blocking temperature was experimentally deduced from zero-field-cooled warmed (ZFC-W) curves by a simple method without employing an external magnetic field. The B-field dependence temperature data of Co–Au nanoparticles exhibited an intrinsic blocking temperature at 45 K. Annealing these samples at 400 °C caused an increase in particle size, crystallinitymore » percentage and further enhanced their magnetic properties.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ; ;  [2] ;  [1]
  1. Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)
  2. Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)
  3. Department of Medical Physics and Biomedical Engineering, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of)
Publication Date:
OSTI Identifier:
22285133
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 48; Journal Issue: 10; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; COERCIVE FORCE; CRYSTALS; FERROMAGNETIC MATERIALS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MICROEMULSIONS; NANOSTRUCTURES; PARTICLE SIZE; PARTICLES; SYNTHESIS; VIBRATING SAMPLE MAGNETOMETERS; X-RAY DIFFRACTION