SAIP2015

Structural and magnetic properties of NiFe₂O₄/NiFe bi-magnet and NiFe nano-alloy synthesized from thermal reduction of NiFe₂O₄

30 Jun 2015, 11:50

20m

Oral Presentation Track A - Division for Physics of Condensed Matter and Materials DPCMM

Speaker

Mr ITEGBEYOGENE EZEKIEL (UKZN)

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD, N/A)?

PhD

Please indicate whether<br>this abstract may be<br>published online<br>(Yes / No)

YES

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

YES

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

Bi-magnetic NiFe₂O₄/NiFe nanocomposites and NiFe nano-alloy were synthesized by reduction of NiFe₂O₄ nano-ferrite with activated charcoal (nc) in flowing high purity Ar gas atmosphere at 900 °C for 3 hours. The parent NiFe₂O₄ nano-ferrite was synthesized by a glycol-thermal method at 200 °C. Partial and complete reduction yielded NiFe₂O₄/NiFe nanocomposites and NiFe nano-alloy respectively. NiFe was formed at an optimum amount of nc = 5. Phase identification, morphology and magnetic properties of the samples were performed by XRD, HRSEM, HRTEM, ⁵⁷Fe Mössbauer spectroscope and a mini cryogenic-free system. The parent sample has an average crystallite size of about 10 nm, an XRD density of about 5.3 g/cm³ and an average lattice parameter of (a) = 8·362±0·007Å. The NiFe nano-alloy exhibited the martensite bcc (α-Fe) and austenite fcc (γ-Fe) phases in coexistence. Fitted Mössbauer analysis for nc = 5 and 6 show high hyperfine magnetic fields associated with the bcc phase while the lower field component is associated with the fcc phase of NiFe nano-alloy. The saturation magnetization increased significantly from 57 emu/g to 141 emu/g at room temperature. The saturation magnetization is enhanced at low temperatures with a maximum of 161 emu/g at ≥ 30 K. However, the coercivity showed no significant increase at low temperatures.

Keywords: Nano-ferrite; Nano-alloy; Nanocomposites; Activated charcoal; martensite; austenite; Reduction reaction

Main supervisor (name and email)<br>and his / her institution

Dr Moyo, Moyo@ukznac.za, University of KwaZulu-Natal, Westville Campus, Durban

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

YES