Speaker
Abstract content <br> (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>
Spinel nickel chromite demonstrates ferrimagnetic ordering below TC = 74 K, and it undergoes several temperature dependent structural and magnetic phase transitions [1]. Recently, it has shown the exchange bias effect, attributed to an anisotropic exchange interaction between the ferrimagnetic and antiferromagnetic components of magnetic moment [2]. These results motivated a detailed investigation into the high temperature structural phase transitions of this material, as well as the effect of calcination on magnetic properties, that are reported here. In-situ high temperature XRD studies of the as synthesized nickel chromite samples measured in air and He atmospheres suggests the phase formation takes place around 800 to 900 °C. The cubic structure of nickel chromite is retained up to almost 1100 °C, contrary to the reported tetragonal phase observed at such elevated temperature [3]. Upon cooling no change in crystal structure is observed. Nickel chromite samples calcined at 900 °C and 1100 °C, respectively, have been used for microstructural and magnetic studies. The particles are found to have a broad size distribution. TC is obtained to be 86 K for the sample calcined at 900 °C, whereas it is reduced to 74 K for the other. The magnetic transition observed at TS = 31 K marking the onset of ordering of antiferromagnetic component, remain unchanged for both the samples. The spontaneous magnetization values for samples calcined at 900 °C and 1100 °C are found to be lesser than reported values [1,4] and they do not show exchange bias effect.
References
[1] Ishibashi H, Yasumi T 2007 J. Magn. Magn. Mater 310 e610
[2] Barman J et al. 2015 J. Magn. Magn. Mater. 385 93
[3] Ptak M et al. 2013 J. Sol. Stat. Chem. 201 270
[4] Mufti N et al. 2010 J. Phys.:Condens. Matter 22 075902
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
N/A
Apply to be<br> considered for a student <br> award (Yes / No)?
No
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
Main supervisor (name and email)<br>and his / her institution
Prof. A R E Prinsloo, alettap@uj.ac.za, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa
