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Title: Exchange-spring mechanism of soft and hard ferrite nanocomposites

Graphical abstract: - Highlights: • Exchange-spring behaviour of soft and hard ferrites was studied. • XRD patterns indicated soft and hard ferrites as fcc and hcp structure. • Hysteresis loops indicate wide difference in coercivity of soft and hard phases. • Nanocomposites produced convex hysteresis loop characteristic of single-phase. - Abstract: The paper reports exchange-spring soft and hard ferrite nanocomposites synthesized by chemical co-precipitation with or without the application of ultrasonic vibration. The composites contained BaFe{sub 12}O{sub 19} as the hard phase and CoFe{sub 2}O{sub 4}/MgFe{sub 2}O{sub 4} as the soft phase. X-ray diffraction patterns of the samples in the optimum calcined condition indicated the presence of soft ferrites as face-centred cubic (fcc) and hard ferrites as hexagonal close packed (hcp) structure respectively. Temperature dependence of magnetization in the range of 20–700 °C demonstrated distinct presence of soft and hard ferrites as magnetic phases which are characterized by wide difference in magnetic anisotropy and coercivity. Exchange-spring mechanism led these nanocomposite systems to exchange-coupled, which ultimately produced convex hysteresis loops characteristic of a single-phase permanent magnet. Fairly high value of coercivity and maximum energy product were observed for the samples in the optimum calcined conditions with a maximum applied field ofmore » 1600 kA/m (2 T)« less
Authors:
 [1] ;  [2] ; ; ;  [3] ; ;  [1] ;  [3]
  1. Materials Science Division, Atomic Energy Centre, Bangladesh Atomic Energy Commission (Bangladesh)
  2. (India)
  3. Department of Materials Engineering, Indian Institute of Science, Bangalore (India)
Publication Date:
OSTI Identifier:
22341727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 48; Journal Issue: 8; 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; 77 NANOSCIENCE AND NANOTECHNOLOGY; ANISOTROPY; COERCIVE FORCE; FCC LATTICES; FERRITE; FERRITES; HCP LATTICES; HYSTERESIS; MAGNETIC PROPERTIES; MAGNETIZATION; NANOCOMPOSITES; NANOSTRUCTURES; PERMANENT MAGNETS; SPRINGS; SYNTHESIS; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION