Authors: Kalengay Mbela T Moyo Nadir S E Osman N Akdoģan M Öztürk
Publish Date: 2016/05/11
Volume: 27, Issue: 9, Pages: 9172-9178
Abstract
Manganese–iron chromium oxides Mn02Cr18−x Fe x O3 with x varying from 03 to 13 have been produced by hydrothermal process in a stirred pressure reactor from pure metal chlorides Single phase corundum structure and nanophase structure of the assynthesized samples were confirmed by Xray diffraction and by transmission electron microscope The results show that the produced powders have an average size of 23 nm The Mössbauer spectra recorded at about 300 K show transition from paramagnetic to ordered magnetic spin state The shift in hysteresis loops observed along the magnetic field axis is associated with exchange bias effect The exchange bias field increases as the particle size decreases with increased Fe content x The loop shifts are different with different particle sizes suggesting that the materials at room temperature may be superparamagneticWe acknowledge the financial support from the DST/NRF South Africa and University of KwaZuluNatal UKZN We are also grateful to the Electron Microscopy Unit at UKZN WC for TEM measurements This work was was partially supported by DPT State Planning Organization Turkey through the Project nos 2009K120730 TṺBITAKRFBRand209T061
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