Nickel-induced magnetic behaviour of nano-structured α-Fe₂O₃, synthesised by facile wet chemical route

ABSTRACT

We report the synthesis of pristine and nickel containing iron oxide (α-Fe₂O₃) nanocrystallites by facile environmentally benign wet chemical process. The magnetic behaviour of the samples has been found to change progressively with nickel content. The Mössbauer spectra revealed the precipitation of secondary phase of nickel ferrite (NiFe₂O₄) at ∼2 wt% nickel contents. The transmission electron micrographs together with asymmetric magnetic hysteresis loop have confirmed the formation of core–shell structure. The Morin temperature of nanostructured α-Fe₂O₃ as estimated by superconducting quantum interference device has been found to be 257, 245, 247 and 242 K at nickel content of 0, 1, 2 and 4 wt%, respectively. The similar trends of increase/decrease in Morin temperature have been noticed by Mössbauer analysis. Furthermore, below Morin temperature, the temperature range of coexisted antiferromagnetic and ferromagnetic states has been found to increase with increase in nickel content.

KEYWORDS:

• α-Fe₂O₃
• NiFe₂O₄
• oxide nanomaterials
• inorganic materials

Acknowledgements

Ondrej Tomanec is acknowledged for TEM analysis of the samples and Petr Novak for the help with processing the Mössbauer spectra.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

One of the authors (SKA) wishes to thank Council of Scientific and Industrial Research (CSIR) for providing her fellowship to carry out this work. The authors acknowledge support from the Ministry of Education, Youth and Sports of the Czech Republic under Project No. LO1305.