engleski

Nanostructured TiO2 - mechanocemical preparation, characterisation and sintering

Nanostructured TiO2 was prepared by high-energy ball milling at different condition. The samples were sintered at high temperatures to investigate its behavior during sintering and properties of final product. Structural changes induced in the sample during the preparation were monitoring by Raman spectroscopy. The changes of the particle dimension were monitored by transmission electron microscopy (TEM) and electron diffraction. Starting material and prepared nanostructured material, achieved by prolonged ball-milling, were additionally studied by X-ray powder diffraction. The sintering processes were performed in argon and monitored at high temperature in situ by Raman spectroscopy. The cooled materials were also investigated by scanning electron microscopy. A different milling time induced sequence of phase transitions, from anatase through high-pressure TiO2 II phase to rutile and prolonged milling decreased the particle to nanometric sizes. The rate of phase transition and diminution, along with purity of nanoparticles TiO2, depended on powder-to-ball weight ratio. X-ray powder diffraction of TiO2, obtained for prolonged ball-milling, showed the same structure as Raman spectroscopy, but it was much accurate for determination of sample contamination due to wearing of milling media. The crystallite sizes, determined from bordering of diffraction lines, were in agreement with particles sizes obtained by TEM of milled TiO2. During sintering of nanosized TiO2 the amorphisation was noticed at lower temperature in relation to the sintering of micron-size TiO2. Sintered samples had smaller grain sizes. The ball-milling was shown to be a simple method for preparation of nanostructured TiO2. Such prepared TiO2 nanoparticles can be good candidate for preparation of nanoceramics.

TiO2 ; ball-milling ; sintering ; Raman ; XRD ; electron microscopy

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