Application of statistical methodology for the evaluation of mechanically activated phase transformation in nanocrystalline TiO2
Response surface methodology was employed to study the effect of three factors, namely as milling time,milling speed and ball to powder weight ratio, on the mechanical activation of polymorphic phase transformationin nanocrystalline TiO2 powder and identify the probable interactions between these factors.The response was the rutile percentage after annealing the samples. Based on the statistical analysis, ballto powder weight ratio was found as the most effective factor and just one statistically significant interactionwas found between milling speed and ball to powder ratio. It was also shown that increasing themilling time has no significant effect on the phase transformation since the required activation energy forthe phase transformation is unattainable under these conditions. The rutile percentage was calculatedfrom X-ray diffraction patterns of the samples via Rietveld refinement method. Raman spectroscopy wasemployed to verify the phase composition analysis based on X-ray diffraction results.