The influence of the precursor clusters on the structural and morphological evolution of nanostructured TiO₂under thermal annealing

Abstract

We have produced nanostructured titanium dioxide thin films by supersonic cluster beam deposition. The as-deposited films have a nanocrystalline or amorphous structure depending on the mass distribution of the precursor clusters. This can be controlled by aerodynamic separation effects typical of supersonic expansions. On thermal annealing at temperatures from 400 to 800 • C in ambient atmosphere, amorphous-to-anatase and anatase-to-rutile phase transitions have been observed. The nanostructure and microstructure evolution of the film upon annealing has been characterized by atomic force microscopy and transmission electron microscopy. The influence of the precursor clusters in the evolution of the film nanostructure at high temperatures has been demonstrated. This observation opens up new perspectives for batch fabrication of devices based on cluster-assembled materials.

Phase transformation of nanostructured titanium dioxide thin films grown by sol–gel method

“…Nanostructured titanium dioxide (n-TiO 2 ) materials have attracted great interest due to their potential applications, such as in photocatalysis, energy storage and transfer, photovoltaic solar cell production, sensor design, pigment production, optical coatings, ceramic manufacturing, wastewater purification, and self-cleaning coating [1][2][3][4][5][6][7][8][9][10][11][12]. However, the phase and morphology of n-TiO 2 have been found to be critical parameters in determining their stability for special applications [13][14][15][16][17].…”

Structural and Optical Properties of Annealed TiO2 Powder Synthesized by Hydrothermal Method

“…Figure-1(a) shows the diffraction patterns of Ti(OH) 4 at annealing temperature 200 • C. the diffraction peak for the plane (110) at 2θ= 27.60 refer to the tetragonal structure belonged to rutile phase, and diffraction peak for the plane (002) at 2θ= 28.53˚ refer to the orthorhombic structure belonged to brookite phase. All the XRD patterns correspond well to the structure of Ti(OH) 4 At the annealing temperature of 800˚C, brookite was totally transformed into rutile Figure-1(d). And based on that the grain size for that peak alone calculated, using the Debye-Scherer formula: D = kλ / βcosθ …………………………………………………………………………………….….…”

“…And based on that the grain size for that peak alone calculated, using the Debye-Scherer formula: D = kλ / βcosθ …………………………………………………………………………………….…. (1) Where k is the constant (0.9),  -ray (1.54nm), β is the full width half maximum (FWHM) of the peak and Ѳ is the reflection angle Table -1 shows the obtained details resulted from XRD for the prepared product (Ti(OH) 4 ) at different annealing temperature (200, 400, 600 and 800˚C) for 120 min.…”

“…The autoclave was sealed and placed in an oven at 200 °C for 6 h. Then, the autoclave was allowed to cool to room temperature naturally. The white precipitate (Ti(OH) 4 ) was washed with distilled water (about 3 times), and collected by centrifugation, washed with ethanol (2 times) and annealed at specify temperature (200-800°C 4 annealing …”

“…It is ntype semiconductor material with wide band gap (Eg= 3-3.3eV) [1]. TiO 2 has high absorption to be like high transparent stability in the visible area and low conductivity, have high refractive index, low cost, nontoxicity, mechanical hardness, novel optoelectronic properties and easy availability [2][3][4]. These properties make TiO 2 the in solar cells, fuel cell, chemical sensors for hydrogen gas evolution, a pigment, self-cleaning surfaces, resistance to photochemical, chemical erosion and environmental purification applications [5,6].…”