Nonlinear size dependence of anatase TiO2 lattice parameters

Abstract

We characterized the size dependence of anatase TiO2 lattice parameters using Rietveld analysis of angle-dispersive synchrotron x-ray diffraction data obtained on a suite of nanocrystalline samples. The refined crystal structure and microstructure data suggest that for crystallites with size less than ∼10nm, the lattice parameters vary nonlinearly. Small lattice expansion, associated with possible increased Ti vacancy and lattice strain, at reduced crystallite size observed in our samples is in contrast to the lattice contraction behavior reported for “pure” anatase nanocrystals. The nonlinear, composition-dependent variation of anatase unit cell volume contrasts with the linear expansion behavior of rutile lattice at finite sizes.

Use of Phonon Confinement Model in Simulation οf Raman Spectra of Nanostructured Materials

“…Let us note that use of asymmetrical Gaussian PSD with proper choice of parameters gives similar results as using PCM with log-normal distribution [11]. The experimental Raman spectra of anatase TiO 2 The change of lattice parameters (lattice volume) with nanoparticle size L decrease is registered in nanomaterials due to effect of microstrain [12,13]. To include the influence of strain on the Raman spectra, the dispersion function ω i (q) in Eq.…”

“…Opposite to CeO 2 , the lattice parameters of tetragonal anatase TiO 2 decrease with nanopartical size decreasing (Fig. 4b) due to compressive strain [12,15]. Therefore, the unit cell volume can be approximated by:…”

Ordered Titanium Dioxide Nanotubular Arrays as Photoanodes for Hydrogen Generation

“…In contrast to the results observed with rutile, lattice contraction is reported in pure anatase nanocrystals with sizes less than 15 nm. Depending on the purity and preparation method, nonlinear expansion is also observed in anatase with crystal sizes less than 10 nm [14]. The internal coordinate value of oxygen also increases from 0.208 to about 0.212 when the anatase crystallite size is 2 nm.…”

Thickness Effect on Fluctuation of Electron States in Thin Film and Implications for Lattice Constant Change Due to Size Reduction

“…In some cases, contraction of the lattice parameter when reducing the particle size has been observed [39][40][41][42][43], which is similar to the behavior of metals. In other cases the antithetical phenomenon was investigated, where expansion of the lattice parameter was observed when reducing the material size [44].…”