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Title: Synthesis of Fe/SiO{sub 2} and iron oxides/SiO{sub 2} nanocomposites by long-term ball milling

Graphical abstract: - Highlights: • Iron–iron oxides/silica composites are synthesized by long term dry ball-milling. • Bcc iron and α-quartz powders are used as precursors. • Surface effects enhance coercivity in iron/silica nanocomposites. • In spite of their small size, about 10 nm, iron particles are ferromagnetic. • Ferro and superparamagnetic particles are found in maghemite/silica composites. - Abstract: Iron oxide/SiO{sub 2} nanocomposites are synthesized by dry ball-milling a mixture of bcc Fe and α-quartz powders for prolonged times. A sequence of nanocomposites is obtained, with small magnetic particles dispersed in a non magnetic, amorphous matrix. The powders are characterized by X-ray diffraction and transmission electron microscopy. The magnetic hysteresis properties are investigated in the range 50–300 K. After 120 h milling, deformed, non-spherical, α-Fe nanocrystallites of about 10 nm in size and very few small (<10 nm) maghemite particles are found. At room temperature, iron particles are ferromagnetic and a large effective magnetic anisotropy is estimated, which is mainly attributed to surface effects. Between 160 and 200 h milling, maghemite nanoparticles are observed while after 220 h grinding, hematite phase appears; after 340 h milling, the sample consists of ferromagnetic hematite particles with a broad size distribution (5–50 nm)more » embedded in an amorphous matrix.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [1] ;  [2]
  1. Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina)
  2. (Argentina)
  3. Centro Atómico Bariloche, Comisión Nacional de Energía Atómica – Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina)
  4. (CONICET) (Argentina)
Publication Date:
OSTI Identifier:
22341834
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 49; 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; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; BCC LATTICES; COERCIVE FORCE; HEMATITE; IRON; MAGNETIC MATERIALS; NANOCOMPOSITES; NANOPARTICLES; NANOSTRUCTURES; POWDERS; SILICA; SILICON OXIDES; SUPERPARAMAGNETISM; SYNTHESIS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION