Structural, vibrational and magnetic properties of Ti substituted bulk hematite: α-Fe2-xTixO3

doi:10.1007/s40145-014-0117-x

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Abstract

Ti doped hematite α-Fe_2-xTi_xO₃ (x = 0.0, 0.0206 and 0.0344) samples are synthesized using solid-state ceramic route technique. Single phase and corundum (Al₂O₃) type structure is revealed from the X-ray diffraction (XRD) pattern. On substitution of Ti at Fe site, all Raman active modes are shifted to higher wave numbers. An additional feature of E_u (LO) mode at about 660 cm^–1 is observed. The E_u mode frequency is decreased and pronounced systematically as a function of Ti doping, and it reaches a value of 658 cm^-1 for x = 0.0344. The coercivity H_c (remanence M_r) for x = 0.0, 0.0206 and 0.0344 are determined to be 995 Oe (0.44 emu/mg), 1404 Oe (0.00019 emu/mg) and 2023 Oe (0.00016 emu/mg), respectively. The larger coercivity for Ti doped samples can be attributed to their enhanced shape and magneto-crystalline anisotropy. The observed isomer shift (δ) from room temperature M?ssbauer data clearly shows the presence of ferric (Fe³⁺) and Ti⁴⁺ ions illustrating strong ferromagnetic ordering up to x = 0.0206 in α-Fe_2-xTi_xO₃ hematite and weak ferromagnetic ordering of α-Fe_2-xTi_xO₃ for x = 0.0344.

Key words： magnetic materials X-ray diffraction (XRD) Raman spectra M?ssbauer spectroscopy

Received: 10 May 2014 Published: 11 June 2015

Corresponding Authors: Dinesh VARSHNEY

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	Dinesh VARSHNEY
	Arvind YOGI

Cite this article:

Dinesh VARSHNEY,Arvind YOGI. Structural, vibrational and magnetic properties of Ti substituted bulk hematite: α-Fe_2-xTi_xO₃[J]. Journal of Advanced Ceramics, 2014, 3(4): 269-277.

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http://jac.tsinghuajournals.com/EN/10.1007/s40145-014-0117-x OR http://jac.tsinghuajournals.com/EN/Y2014/V3/I4/269

XRD patterns for α-Fe_2-xTi_xO₃ (x = 0.0, 0.0206 and 0.0344).

Raman shift (ν) and full width at half maximum (FWHM, Γ) for hematite at a laser power of 5 mW

Raman scattering intensities shown as a function of Raman shift (or wave number) for α-Fe_2-xTi_xO₃ (x = 0.0, 0.0206 and 0.0344) at 300 K. Inset showing the E_u mode for α-Fe₂O₃.

Remnant magnetization (M_r) and coercive force (H_c) for Ti doped α-Fe_2-xTi_xO₃

Hysteresis loop for parent α-Fe₂O₃ sample at room temperature (300 K).

Hysteresis loop for Ti doped hematite α-Fe_1.9794Ti_0.0206O₃ sample at room temperature (300 K).

Hysteresis loop for Ti doped hematite α-Fe_1.9656Ti_0.0344O₃ sample at room temperature (300 K).

⁵⁷Fe M?ssbauer parameters for Ti doped α-Fe_2-XTi_XO₃

Room temperature M?ssbauer spectra for α-Fe_2-xTi_xO₃ (x = 0.0, 0.0206 and 0.0344) hematite.

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