Title
Size dependence of the magnetic and hyperfine properties of nanostructured hematite (α-Fe<inf>2</inf>O<inf>3</inf>) powders prepared by the ball milling technique
Date Issued
01 January 2014
Access level
metadata only access
Resource Type
research article
Author(s)
André-Filho J.
Garg V.
Oliveira A.
Universidade de Brasília
Universidade de Brasília
Abstract
In this work we present the study of hematite (α-Fe2O3) nanostructures synthesized by the ball milling technique. The structural characterization and the crystallite size estimation have been carried out using the X-ray diffraction (XRD) technique. Data analyses indicate that the hematite phase (space group, R-3C) is preserved after the milling process. As the milling time is increased, a second phase (α-Fe) appears. The mean crystallite size shows a decreasing tendency as the milling time is increased. High-resolution transmission electron microscopy (HRTEM) images show the formation of grains composed of crystallites with irregular shapes. Mössbauer spectra of milled powders carried out at 297 and 77 K are well modeled with a histogram distribution of hyperfine fields. The presence of one additional sextet which corresponds to the ∝-Fe phase is also determined in agreement with XRD data analysis. Magnetic measurements suggest the suppression of the Morin transition in the milled samples and the absence of thermal relaxation effects in agreement with the Mössbauer spectroscopy results. © 2013 Springer Science+Business Media Dordrecht.
Start page
189
End page
196
Volume
224
Issue
March 1
Language
English
OCDE Knowledge area
Física nuclear
Scopus EID
2-s2.0-84889251277
Source
Hyperfine Interactions
ISSN of the container
03043843
Sponsor(s)
Acknowledgements The authors thank the Brazilian agencies CNPq and CAPES for the financial support. Thanks to the Dr. J. Dias for carrying out the X-ray diffraction experiments.
Sources of information: Directorio de Producción Científica Scopus