Structural Aspects of Anatase to Rutile Phase Transition in Titanium Dioxide Powders Elucidated by the Rietveld Method

Abstract

Titanium dioxide has attracted much attention since a long time ago due to its versatility as advanced material. However, its performance as semiconductor devices is very much dependent on the predominant crystalline phase and defect concentrations, which can be adjusted through the synthesis methods, thermal treatments and doping processes. In this work, an accurate structural characterization of titanium dioxide was used by X-ray diffractometry supported by rietveld refinement and thermal analysis. The insertion of 5 mol% of zirconium silicate was able to stabilize anatase up to 900 C, permitting the oxygen vacancies to be significantly eliminated. It was demonstrated also that the changes in the isotropic thermal parameters for oxygen are related to reconstructive transformation necessary to promote the anatase-to-rutile phase transition. Independently of doping process, the crystallization process of anatase phase as a function of temperature increasing occurs exclusively due the reduction of lattice microstrain up to 600 C. However, above 650 C, that crystallization process becomes dependent of the increasing in crystallite size. The anatase crystallite growth event was only possible when the titanium dioxide was doped with zirconium silicate. Otherwise, the rutile phase amount starts to rise continually. Thus, there are optimistic expectations for that new composition to be a new semiconductor matrix for additional doping processes.

Effect of Thermal Treatment on the Phase Composition and Surface Properties of WO3‐TiO2 Nanocomposites Synthesized via Hydro‐Thermal Method

“…Initially, all of the TiO 2 exists in anatase phase only due to its less constrained structure and lower surface free energy. Anatase phase to rutile phase transition (ART) begins at temperature above 500 °C and depends on many factors like calcination temperature and heating rate [48,49] . The presence of rutile phase peaks in the samples calcinated at 600 °C and 800 °C suggest that the transition of anatase phase into rutile occurs at temperature above 500 °C.…”

How Can the Introduction of Zr4+ Ions into TiO2 Nanomaterial Impact the DSSC Photoconversion Efficiency? A Comprehensive Theoretical and Experimental Consideration

“…Aside from nanoparticles’ size-changing during the time elongation of the calcination process, the phase structure of investigated samples has also changed. Dried TiO 2 matrices annealed at 450 °C for 1 h are single-phase products, whereas the rutile and brookite phases appeared in the titania nanoparticles calcinated for 2 h. However, introducing Zr 4+ ions into TiO 2 or annealing TiO 2 paste on FTO glass caused inhibition of the anatase to rutile phase transformation [ 46 , 47 , 48 ].…”

Crystallized TiO2 Nanosurfaces in Biomedical Applications

“…The crystallization of amorphous solid nanosurfaces can be explained as a process in which the atoms are organized into a crystal through nucleation (the appearance of a crystalline phase) and crystal growth (the appearance of a crystalline phase from either a supercooled liquid or a supersaturated solvent). The mechanism of the crystallization of amorphous TiO 2 nanosurfaces, as well as the kinetics and mechanisms of the solid state transformation from anatase to rutile, can be found elsewhere [ 28 , 29 , 30 ]. Briefly, the crystallization of TiO 2 nanosurfaces is governed by an increased temperature; the amorphous material is transformed to a lower temperature phase—anatase [ 28 ]—and upon further heating to 400–1200 °C [ 31 , 32 ], into a rutile phase.…”