Naslov
Structural investigations of nanocrystalline TiO2 samples

Autori
Djerdj, Igor ; Tonejc, Anđelka ; Tonejc, Antun

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Electron Crystallography: Novel Approaches for Structure Determination of Nanosized Materials / Labar, Janos ; Weirich Thomas ; Zou, Xiaodong - Erice : Ettore Majorama Foundation centre and Centre for Scienticic Culture, 2004, 1-1

Skup
International School of Crystallography

Mjesto i datum
Erice, Italija, 09.06.2004. - 20.06.2004

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
nanocrystalline materials; SAED; XRD

Sažetak
Two kinds of nanocrystalline TiO2 samples were synthesized by the sol-gel method: iron doped TiO2 (containing iron as a solid solution and poly(ethylene)glycol) and undoped TiO2. The structural parameters and the phase composition of the synthesized samples have been investigated using the Rietveld method of X-ray diffraction (XRD) in conjunction with the Rietveld method of selected area electron diffraction (SAED). Both methods gave the similar values of structural parameters, indicating the possibility of use of SAED in quantitative structural analysis. Significant differences of lattice parameters, bond lengths and angles were found between undoped and iron doped samples. The average grain size and lattice microstrain were determined through the line-broadening analyses using the Rietveld method based on the single-line approach and Warren-Averbach method. The grain-size dependencies of the lattice parameters of anatase, microstrain, and unit-cell volume were determined. The lattice parameter a was found to increase while the parameter c decreased with a decreasing of the grain size, keeping the unit-cell volume almost constant. The variations of the lattice parameter deviation from the ICDD values with the average grain size can be well correlated with the grain-size dependencies of the corresponding microstrains. Upon annealing at elevated temperature the grain growth occurred and lattice microstrain decreased, due to the annihilation of dislocations. The results from the exhaustive XRD analysis were confirmed with transmission electron microscopy (TEM). In addition, fine details in material characterization were observed. The most probable microstructural model of investigated nanocrystalline TiO2 is a model in which defects are uniformly distributed throughout individual grains, but whose concentration is proportional to the inverse grain size.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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