Abstract
This paper reports the particle size characterisation of mechanically alloyed La0,5Sr0,5Fe0,5Mn0,25Ti0,25O3 prepared with the assistance of a high-power ultrasonic treatment. After a solid-state reaction on quasi-crystalline powders at 1000°C for 3 hour, the presence of a single phase was confirmed by X-ray Diffraction (XRD). It was found that powder materials derived from mechanical alloying and successive sintering have several disadvantages, namely, that the particle morphology is seldom controllable and results in large variations in the particle size and distribution. A significant improvement in both particle size and distribution was obtained upon subjecting the mechanically milled powder materials to an ultrasonication treatment for a relatively short period of time. As determined by a particle size analyser, the mean particle size gradually decreased from the original size of 6.23 to 1.13mm. A narrow size variation was also observed by Scanning Electron Microscope (SEM). The line broadening analysis by XRD revealed that the particles consist of nanocrystallites with an average size of ~ 22-26 nm. These results indicate that the sintering of mechanically milled particles followed by a high-power ultrasonication treatment promotes the formation of particles containing nanocrystals.
Highlights
Perovskite lanthanum manganites, especially those doped LaMnO3 (LMO), have shown significant potential for application in the field of magnetic electronic functional materials (Zi et al, 2009)
Beginning with quasi-crystalline materials obtained from mechanical alloying and successive sintering to induce crystallisation, a further refinement of the particle size is afforded by the application of a high-power sonicator
The X-ray Diffraction (XRD) traces of sintered powders obtained using sintering temperatures in the range of 800-1200 oC exhibit a pattern similar to that of the LaMnO3 phase
Summary
Perovskite lanthanum manganites, especially those doped LaMnO3 (LMO), have shown significant potential for application in the field of magnetic electronic functional materials (Zi et al, 2009). Structural modification either through doping of La with Ca, Sr, and Ba (Pissas, Kallias, Hofmann, & Tobbens, 2002; Grossin & Noudem, 2004) or Mn with Fe, Cu, and Ti (Ahn, Wu, Liu, & Chien, 1997; Li et al, 2006; Kallel, Oumezzine, & Vincent, 2008) have been reported to induce electromagnetic properties such as giant magneto resistance (GMR) or colossal magneto resistance (CMR) (Haghiri-Gosnet & Renard, 2003; Ramirez, 1997) Another potential application is in the area of radar-absorbing materials (RAM) (Gama, Rezende, & Dantas, 2011). Beginning with quasi-crystalline materials obtained from mechanical alloying and successive sintering to induce crystallisation, a further refinement of the particle size is afforded by the application of a high-power sonicator
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