Speaker
Mr
Itegbeyogene Ezekiel
(University of KwaZulu-Natal)
Description
Structural and magnetic properties of sintered and milled La0.67Sr0.33MnO3 was investigated in the temperature range of 300-2 K. The refined X-ray diffraction (XRD) data show that all samples are single phase and crystallize in rhombohedral symmetry with R-3C space group. The as-prepared samples (SK) where milled for 1, 3, 6 and 12 hours (SKM1, SKM3, SKM6 and SKM12). The crystallite size decreased from 46-11 nm as a function of milling except for SKM12 which increased slightly to 12 nm due to thermal effect of prolonged milling. The cell volume increased from 349-352 Å3 except for SKM12 which dropped to 349 Å3 due to peak shift to a higher 2θ as a result of strain. High-resolution transmission electron microscopy HRTEM and high-resolution scanning electron microscopy HRSEM of the samples show a variation in the morphology. The saturation magnetisation MS was estimated from the hysteresis loops using the law of approach to saturation magnetisation. MS for all samples increases as temperature decreases. At the maximum and minimum measuring temperature of 300 K and 2 K respectively, the MS for SK, SKM1, SKM3, SKM6 SKM12, are 52, 45, 22, 13, 7 emu/g and 80, 79, 64, 53, 40 emu/g respectively. The drop in MS has been explored based on a core-shell model. The coercivity at 2 K showed a significant increase from 0.17 kOe for SK to 0.87 kOe for SKM12. The hysteresis loops of all samples at 2 K exhibit a trend from superparamagnetism to ferromagnetism, while at 300 K, a trend of superparamagnetism to paramagnetism is observed.
Summary
Mechanical milling, superparamagnetism, paramagnetism, ferromagnetism
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
PhD
Main supervisor (name and email)<br>and his / her institution
Dr. Thomas Moyo, moyo@ukzn.ac.za
University of KwaZulu-Natal
Westville Campus, Durban, South Africa
Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?
Yes
Apply to be<br> considered for a student <br> award (Yes / No)?
Yes
Primary author
Mr
Itegbeyogene Ezekiel
(University of KwaZulu-Natal)
Co-author
Dr
Thomas Moyo
(University of KwaZulu-Natal)
