Characterization of nanophase titania particles synthesized using in situ steric stabilization

Abstract

Ultrafine titania particles were synthesized from titanium tetraethoxide (TEOT) dissolved in ethanol. The concentration of water and of the soluble polymer hydroxypropylcellulose (HPC) were varied to control particle size. The HPC adsorbed onto the titania particles during growth, providing a steric barrier to aggregation. Electron microscopy showed that particles smaller than 70 nm were formed at high water concentrations (R > 120 where R is the molar ratio [H2O]/[TEOT]) and in the presence of HPC. The annealing-induced, phase-transformation behavior of these particles (amorphous → anatase → rutile) from 100 to 1000 °C was characterized by x-ray, Raman, and infrared techniques. The conversion of anatase to rutile occurred more readily for particles made at high water concentrations and with HPC. For particles formed by premixing TEOT with HPC prior to hydrolysis at R = 155, an 800 °C anneal yielded a rutile fraction exceeding 95%; particles made at R = 5.5 with no HPC showed negligible conversion at this temperature.

Anodic preparation of porous TiO 2 in fluoride solution

“…The Raman spectra of the samples prepared in 0.2 M NH 4 F at pH 3 and 4 showed broad structures around 420 and 600 cm -1 . The Raman spectra of these samples are very similar to the Raman spectrum of amorphous TiO 2 nano-powder synthesised using in-situ steric stabilization [4]. The Raman spectra of the samples anodized in 0.2 M NH 4 F at pH 5 and 6.5 were nearly identical.…”

Antimicrobial properties of highly efficient photocatalytic TiO2 nanotubes

“…4b and c) measurements confirmed that the nanotubes were mostly amorphous. The XRD spectrum, typical for partially crystalline with amorphous titania nanostructures [10], exhibits only a very broad maximum around the main theoretical anatase peak (2Â = 25.3 • ). Previous XPS studies on the material [11] confirmed that the chemical bonds between Ti and O correspond to the TiO 2 molecule.…”

Plasma-Assisted Chemical Vapor Deposition of TiO<sub>2</sub> Thin Films for Highly Hydrophilic Performance

“…Typical peaks corresponding to anatase-TiO 2 were appeared at 144, 399, 514 and 639 cm −1 in the layers grown above 340˚C, where the peaks were attributed to E g , B 1g , B 2g and E g vibration modes respectively [19]. However, any peaks except a weak broadband around 450 cm −1 , which was recognized due to amorphous phase of TiO x [20], could not be observed for the layer grown at 250˚C.…”