Bimodal Size Distribution and Shape Anisotropy in Ball-Milled Nano-Sized α-Al2O3 |
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Authors: | A. K. Deb P. Chatterjee S. P. Sen Gupta |
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Affiliation: | a Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, Indiab Department of Physics, Vivekananda Mahavidyalaya, Haripal, Hooghly, India |
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Abstract: | -Al2O3 prepared by combustion technique was ball-billed in a planetary mill in toluene medium at 300 rpm in ZrO2 pot with a ball to powder ratio 10:1 for 1, 5, 10, 15, and 20 hours. X-ray diffraction pattern from the milled materials showed super-Lorentzian peak shapes for -Al2O3 peak profiles. The super-Lorentzian peak shape has been attributed to the bimodal size distribution of the -Al2O3 particles. Rietveld analysis using two different phase fractions of -Al2O3 with different microstructural features yielded a low goodness-of-fit of the x-ray data indicating the suitability of the assumed model. The phase fraction of -Al2O3 particles with smaller size increases with the milling time. Further the particles shapes were observed to be cylindrical in this case with the cylinder axis along the crystallographic c-axis. The cylinder diameter and the length were obtained to be 86 and 140 respectively after 20 hrs of milling. The -Al2O3 particles of larger size are isotropic. It is, thus, proposed that milling induces bimodal size distribution in the initial hours of milling. |
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Keywords: | α-Al2O3 Ball-mill Bimodal distribution X-ray diffraction |
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