Abstract

This paper reports the particle size characterisation of mechanically alloyed La_0,5Sr_0,5Fe_0,5Mn_0,25Ti_0,25O₃ 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.

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