engleski

X-Ray diffraction study of thermal properties of titanium dioxide

Temperature dependence of microstructure of titanium dioxide, TiO2, and the phase transition of anatase (A) to rutile (R) were studied by in situ X-ray powder diffraction. The as-synthesized TiO2 p.a. showed a gradual transition A!R during the temperature increase from 1200 K to 1570 K and during the temperature decrease to 600 K. High-energy ball milling at room temperature induced a par- tial transition A!R. The transition continued during the temperature increase to  1370 K and during the temperature decrease, and is accompanied by sharpening of diffraction lines. Anisotropy of thermal expansion was noticed for both A and R. In the transition A!R, the nuclei of R are formed either throughout the A crystallites (in the case of as-synthesized TiO2 p.a.) or mainly in the interior of the A crystallites (in the case of the milled TiO2 p.a.). These nuclei grow in number and size with a prolonged time of thermal agitation.

titanium dioxide ; rutile ; anatase ; phase transition ; thermal expansion ; X-ray

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