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Solid-state ceramic technique route is used for synthesizing Cr-doped haematite α-Fe2-xCrxO3 (x = 0, 0.125, 0.50 and 1) samples. Single phase and corundum (Al2O3) type structure is revealed from the X-ray diffraction (XRD) patterns. The Raman spectra of α-Fe2-xCrxO3 illustrate seven phonon modes. On substitution of Cr (x = 0, 0.125, 0.50 and 1) at Fe site, all Raman active modes are shifted to higher wave numbers. The coercivity and remanence of Cr-doped haematites increase as x increases. The increased coercivity and remanence for Cr-doped samples can be attributed to their enhanced shape and magneto-crystalline anisotropy. The observed isomer shift δ values from room-temperature Mössbauer data clearly show the presence of ferric (Fe3+) and Cr3+ ions illustrating strong ferromagnetic ordering up to x = 0.125 in α-Fe2-xCrxO3 haematite and weak ferromagnetic ordering for α-Fe2-xCrxO3 (x > 0.125) haematites.


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Magnetic and structural properties of pure and Cr-doped haematite: α-Fe2-xCrxO3 (0 ≤ x ≤ 1)

Show Author's information Arvind YOGIa,bDinesh VARSHNEYa,*( )
Materials Science Laboratory, School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001, India
School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram 695016, India

Abstract

Solid-state ceramic technique route is used for synthesizing Cr-doped haematite α-Fe2-xCrxO3 (x = 0, 0.125, 0.50 and 1) samples. Single phase and corundum (Al2O3) type structure is revealed from the X-ray diffraction (XRD) patterns. The Raman spectra of α-Fe2-xCrxO3 illustrate seven phonon modes. On substitution of Cr (x = 0, 0.125, 0.50 and 1) at Fe site, all Raman active modes are shifted to higher wave numbers. The coercivity and remanence of Cr-doped haematites increase as x increases. The increased coercivity and remanence for Cr-doped samples can be attributed to their enhanced shape and magneto-crystalline anisotropy. The observed isomer shift δ values from room-temperature Mössbauer data clearly show the presence of ferric (Fe3+) and Cr3+ ions illustrating strong ferromagnetic ordering up to x = 0.125 in α-Fe2-xCrxO3 haematite and weak ferromagnetic ordering for α-Fe2-xCrxO3 (x > 0.125) haematites.

Keywords:

magnetic materials, X-ray diffraction (XRD), Raman spectra, Mössbauer spectroscopy
Received: 24 July 2013 Revised: 23 September 2013 Accepted: 13 October 2013 Published: 04 December 2013 Issue date: December 2013
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Publication history
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Publication history

Received: 24 July 2013
Revised: 23 September 2013
Accepted: 13 October 2013
Published: 04 December 2013
Issue date: December 2013

Copyright

© The author(s) 2013

Acknowledgements

Authors are thankful to UGC New Delhi for financial assistance and to UGC-DAE CSR, Indore for providing characterization facilities. Useful discussions with Dr. D. M. Phase, Dr. R. J. Choudhary, Dr. V. Sathe and Dr. V. R. Reddy are gratefully acknowledged.

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