Wyniki wyszukiwania - BazTech

1

Effect of titanium source and sol-gel TiO2 thin film formation parameters on its morphology and photocatalytic activity

Dulian Piotr, Zajic Jan, Żukowski Witold

Materials Science Poland

|

2020

|

Vol. 38, No. 3

424--433

EN

TiO2 thin films with different surface structure have been prepared from alkoxide solutions by the sol-gel method using different cationic precursors and heat treatment techniques. The effect of using titanium isopropoxide as well as titanium butoxide as a titanium source on the surface structure and photocatalytic activity of the resultant thin films was studied. Significant differences in the rate of hydrolysis and condensation reactions during the sol-gel synthesis were observed for these titanium precursors. This had a direct influence on the morphology of the as-prepared TiO2 films. Higher quality oxide coatings were obtained from titanium isopropoxide. They were characterized by a smaller grain size, improved surface roughness and uniform coverage of the glass substrate. A beneficial effect of calcination process after each sol application cycle in contrast to single step calcination after all dip-coating cycles was observed. Photocatalytic degradation tests showed that methyl orange was decolorized in the presence of all prepared TiO2 films by exposing their aqueous solutions to UV light (λ = 254 nm). The highest photocatalytic activity had the TiO2 layer produced using titanium isopropoxide.

2

Synthesis and characterization of TiO2 thin film on fly ash cenospheres

Szołdra Paulina, Pichór Waldemar, Cholewa-Kowalska Katarzyna, Adamczyk Anna, Szudek Wojciech

Composites Theory and Practice

|

2019

|

R. 19, nr 2

71--75

EN

Titanium dioxide (TiO2) thin films obtained on quartz glass and fly ash cenospheres were studied. Titanium(IV) butoxide (Ti(OBu)4), diethanoloamine (DEA), ethanol and deionized water were used as the starting materials. A layer of TiO2 nanoparticles was coated on the surface of the substrates using the sol-gel method. The thickness of the TiO2 coatings and the influence of the annealing temperature on the formation of TiO2 crystallites were studied. The dried gels were treated for 90 min in the temperature range of 400÷640°C to obtain crystallized anatase and rutile. Additional nanopowder TiO2 samples were prepared and their crystallinity was determined using X-ray diffraction (XRD). It was successfully shown that the anatase crystalline phase is formed when the TiO2 gel is heated to 480°C, while the rutile phase is obtained at 640°C. Changes in film thickness were studied using an atomic force microscope (AFM). The profound effect of gel viscosity on the thickness of the film was noticed. UV-Vis absorption spectroscopy, performed on the sample treated at 480°C (containing anatase phase only), showed strong ultraviolet light absorption below 400 nm. The estimated band-gap value was 3.2 eV. Transmission scanning microscopy (TEM) examination of the powders revealed agglomerated nanoparticles. A uniform, continuous layer on the surface of the treated microspheres was observed under a scanning electron microscope (SEM). The study shows that the annealing temperature has a profound effect on the phase composition and crystallite size of the sol-gel synthesized TiO2 nanopowders.

PL

Badaniom poddano warstwy z dwutlenku tytanu (TiO2), które zostały osadzone na powierzchni szkła kwarcowego i mikrosfer z popiołów lotnych. Wyjściowymi substratami były butanolan tytanu(IV) (Ti(OBu)4), dietanoloamina (DEA), etanol i woda dejonizowana. Warstwy z nanocząstkami TiO2 przygotowano, wykorzystując metodę zol-żel. Zbadano grubość otrzymanych warstw oraz wpływ temperatury wypalania na powstawanie krystalitów TiO2 syntetyzowanych w zol-żelu. Wysuszone żele poddano obróbce termicznej w zakresie temperatur 400÷640°C przez 90 minut w celu uzyskania krystalicznych form anatazu i rutylu. Za pomocą dyfrakcji rentgenowskiej (XRD) określono skład fazowy nanoproszków TiO2. Udało się wykazać, że krystaliczny anataz otrzymywany jest podczas ogrzewania żelu w temperaturze 480°C, natomiast krystaliczna faza rutylowa w 640°C. Zmianę grubości warstwy obserwowano z wykorzystaniem mikroskopu sił atomowych (AFM). Zaobserwowano duży wpływ lepkości zolu na grubość otrzymywanych powłok. Przeprowadzona przy użyciu spektroskopii absorpcyjnej UV-Vis analiza próbki poddanej obróbce termicznej w 480°C (w której jedyną występującą fazą był anataz) wykazała silną absorpcję promieniowania ultrafioletowego o długości fali poniżej 400 nm. Szacowana wartość energii pasma wzbronionego wynosiła 3,2 eV. Obrazy z transmisyjnego mikroskopu skaningowego (TEM) ukazały zaglomerowane nanocząstki, a obrazy ze skaningowego mikroskopu elektronowego (SEM) pokazały jednorodną warstwę na mikrosferach. Wykonane badania pokazują, że temperatura wypalania ma ogromny wpływ na skład fazowy i rozmiar krystalitów nanoproszków TiO2 syntetyzowanych metodą zol-żel.

3

Influence of calcination temperature on optical and structural properties of TiO2 thin films prepared by means of sol-gel and spin coating

Tański T., Matysiak W., Kosmalska D., Lubos A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2018

|

Vol. 66, nr 2

151--156

EN

In this study, ceramic TiO2 thin films were prepared on glass substrates using sol-gel and spin-coating methods from the TNBT/ AcOH/ EtOH/ H2O solution. The obtained coatings were subjected to drying at room temperature and were then calcined in the air at different temperatures in a range of 400–600°C in order to obtain clean TiO2 layers. The surface morphology and chemical composition were characterized with the use of a scanning electron microscope (SEM) and an energy dispersive spectrometer (EDX). Research has shown the presence of elements in the TiO2 and the influence of temperatures on layer thickness. Analysis of optical properties and energy gap width of the prepared coatings was determined by means of spectra analysis of absorbance as a function of radiation energy obtained with the use of the UV-VIS spectrophotometer. The obtained spectra of the layers are characterized by a shift of absorption lines towards the visible light wavelengths and the obtained values of band gaps decrease as the calcination temperature rises. The obtained and developed results of TiO2 thin films testify to the wide application possibilities of the layers in elements which use photocatalytic processes such as self-cleaning surfaces, solar cells, pollution removing membranes and optoelectronic components.

4

Optical properties and morphology of PECVD deposited titanium dioxide films

Kowalski J., Sobczyk-Guzenda A., Szymanowski H., Gazicki-Lipman M.

Journal of Achievements in Materials and Manufacturing Engineering

|

2009

|

Vol. 37, nr 2

298-303

EN

Purpose: The purpose of the present work is to compare the structure and optical properties, with respect to their potential optical applications, of titanium dioxide films synthesized with the PECVD method from two different precursor materials, namely titanium tetrachloride and titanium tetraethoxide (TEOT). Design/methodology/approach: Optical properties as well as thickness of the films were analyzed by means of Variable Angle Spectroscopic Ellipsometry (VASE). Morphology studies were carried out by Scanning Electron Microscopy (SEM) and chemical composition characterisation was performed with the help of Energy Dispersive Spectroscopy (EDS) unit coupled with the electron microscope. Findings: Optical parameters approaching those of titanium dioxide were achieved for both precursors. Studies of morphology show that the films produced from TEOT have favourable, smooth surface in contradiction to broccoli-like structure obtained for the chloride precursor. The type of substance used for titanium oxides synthesis determined chemical composition of the films resulting in their enrichment with either chlorine or carbon, depending on the precursor composition. Practical implications: The optical quality of the films is good enough to suggest their applications in stack multilayer interference filters. The refractive index values of these films advocate their use as high refractive index materials while their low extinction coefficients assure the devices transparency. Originality/value: The work presents deposition rates as well as the films optical properties, chemical composition and morphology in relation to operational parameters of their synthesis. It also provides a comparison of these characteristics for two competitive precursor compounds. Finally, it presents the capability of PECVD method for the deposition of optical coatings onto polymer substrates.

5

Bactericidal and hydrophilic plasma deposited thin TiO2 films on glass substrate

Sobczyk-Guzenda A., Szymanowski H., Gazicki-Lipman M., Kowalski J., Jakubowski W., Halamus T.

Engineering of Biomaterials

|

2009

|

Vol. 12, no. 85

8--12

EN

In recent years, titanium dioxide has attracted a great deal of attention as a material for photocatalytic applications. These applications include antibacterial effect as well as photocatalytic air and water purification. Another property of TiO2 concerns a substantial increase of its surface hydrophilicity upon irradiation. The aim of this work is to investigate thin TiO2films obtained by RF PECVD technique with respect to hydrophilic and long-term bactericidal activity. Structural studies, carried out by Raman spectroscopy show that all the investigated coatings are amorphous. The films exhibit agglomerates, with their amount depending on energetic conditions of deposition. Adhesion measured by a scratch test shows that films deposited at higher RF power adhere better than those synthesized at lower power values. UV irradiation causes death of nearly 100% of Escherichia coli population on TiO2films. The irradiated films are still active for about 30 min after the end of UV exposure. A substantial decrease of water contact angle is also observed upon the irradiation of the films with UV light.