Properties Of Titanium Dioxide Films Research Articles

Influence of carbon-ion irradiation and hydrogen-plasma treatment on photocatalytic properties of titanium dioxide films

Effects of carbon-ion irradiation and hydrogen-plasma treatment for anatase TiO 2 films were examined by decomposition of a dye, and the photoinduced transient charge separation (PITCS) method. For the TiO 2 films prepared by anodic oxidation, the photocatalytic activity decreased with increasing carbon-ion dose in a range of 10 13–10 16 ions/cm 2. In particular, the activity drastically decreased when the carbon-ion dose was about 10 15 ions/cm 2. From the PITCS measurements, it was found that the transport of holes toward the TiO 2 surface was retarded by carbon-ion dose. After hydrogen-plasma treatments, the activity was lower than that of as-prepared TiO 2. For TiO 2 films grown by pulsed laser deposition and carried out hydrogen-plasma treatment, on the contrary, the activity was higher than that of pristine TiO 2.

Dependence of Semiconductive Properties of Titanium Oxide Film on the Growth Rate and Formation Potential

Semiconductive properties of a titanium anodic oxide film are found to depend on the film formation rate and potential. Both donor density and flat-band potential obey a power dependence on the formation potential with the coefficients depending linearly on the logarithm of the growth rate. The donor density increases with the temperature following an Arrhenius-like equation.

Mechanical properties of titanium oxide film deposited on LTI-carbon by IBED

Titanium oxide films were deposited on low temperature isotropic pyrolytic carbon (LTI-carbon) by ion beam enhanced deposition, and its mechanical properties such as ultramicrohardness, adhesion strength and fatigue property were studied. The microhardness of titanium oxide films prepared at different experimental conditions is maintained between 900 and 1000 kg/mm 2, when measured by UMHT-3 ultramicrohardness tester installed in the scan electronic microscope. The adhesion strength measurement results show that the adhesion strength of titanium oxide films on LTI-carbon substrate is approximately 0.314–0.47 GPa. The deposition of Ti interlayer is beneficial to improve the adhesion strength of the film. Subsequently, the film with the highest adhesion strength was coated on mechanical heart valves, and the fatigue and wear resistance of the film was investigated in a simulated heart-valve-working environment. After 675 500 times of opening-and-closing cycles, a circular abrasion trail appeared, whereas titanium oxide was still present in this area. No peel of the film was observed. When the cycles increased to 1 617 000 times, a small part of the film located at the inboard boundary of the wear trail peeled off, however, Ti still could be detected in the wear trail region.

Properties of titanium dioxide films prepared by reactive electron-beam evaporation from various starting materials.

There is a wide choice of starting materials for the production of titanium dioxide films by reactive electron-beam evaporation. We have investigated the specific merits of these materials in terms of refractive index, stress, and abrasion resistance of the resultant titanium dioxide films. The suboxides TiO, Ti2O3, and Ti3O5 as well as titanium dioxide and titanium metal were reactively evaporated, and titanium dioxide films free of absorption were obtained on substrates at 25 and 250 degrees C. On unheated substrates the refractive index, which varies from 2.06 to 2.22, the stress, and the abrasion resistance all depend on the starting material used. On substrates heated to 250 degrees C the refractive indices of all films lie closely about 2.4, and all films show high tensile stress and good abrasion resistance.

Properties of titanium oxide films obtained by PECVD

Amorphous TiO 2 films containing carbon and excess oxygen were deposited from glow discharge plasmas of titanium tetraisopropoxide Ti(OC 3H 7) 4, helium, oxygen and argon mixtures. The discharge was generated in a stainless steel vacuum chamber by two parallel-plate electrodes connected to a 13.56 MHz power supply. A substrate holder, to which a d.c. bias voltage could be applied, was positioned outside the region between the two electrodes, i.e. in a region of lower plasma density. The substrate voltage bias, V B, and the ratio of the partial pressures of O 2 to Ti(OC 3H 7) 4 [oxygen to precursor (OTP) ratio] in the chamber were adopted as the principal deposition parameters. Details of the molecular structure of the films were investigated by infrared spectroscopy and X-ray photoelectron spectroscopy. The latter was also used to determine the O/Ti and C/Ti atomic ratios at the film surface. The total (surface and bulk) O/Ti and C/Ti atomic ratios were determined using Rutherford backscattering spectroscopy. While neither the surface nor the total O/Ti ratio varied significantly with V B and the OTP ratio, both the surface and total C/Ti ratios varied strongly with these parameters. The refractive index, determined by ultraviolet-visible spectroscopy, and the electrical conductivity, measured by a two-point probe, were influenced by the polarity and magnitude of V B.

Non-linear optical properties of titanium dioxide films containing dispersed gold particles

Rutile-type TiO 2 films containing dispersed Au particles and having a refractive index of 2.7 were prepared by a multitarget sputtering method at a substrate temperature of 600°C. In spite of the bombardment of Au particles during the TiO 2 sputtering process, | χ (3)|/ α was 3 × 10 −10 esu cm, which was 1.5 times larger than that calculated from the local field effect on Au particles in a TiO 2 matrix. This increase in | χ (3)|/ α indicates an increase in | χ m (3)| of the Au particles themselves. After laser irradiation, | χ (3)|/ α increased to a maximum of 2 × 10 −8 esu cm which was about 100 times larger than that of conventional materials containing dispersed metal particles.

Properties of titanium oxide film prepared by reactive cathodic vacuum arc deposition

TiO2 thin films were deposited on a soda-glass substrate as a function of gas pressure (0.1–2.0Pa) using conventional unfiltered vacuum arc deposition (UFA), and also deposited using a macroparticle-filtered arc deposition source (FAD). Crystalline structure, microhardness, elastic modulus, and optical properties (transmittance, reflectance, refractive index, extinction coefficient, absorption coefficient, and optical bandgap) were measured or evaluated. All films deposited on unheated substrates were amorphous, and post-annealed films as well as films deposited with in-situ heating were of the crystalline anatase phase. Similar mechanical and optical properties were obtained for the films deposited by UFA over a wide pressure range (0.1–1.0Pa). After the annealing process, the films became harder, and the extinction coefficient of the film increased. The transmittance and the extinction coefficients of films deposited by FAD were found to be slightly superior to those of films deposited by UFA. The optical bandgap was about 3.25eV for as-deposited amorphous material prepared by both UFA and FAD as well as for in-situ heated anatase film prepared by FAD.

Electrochromic behaviour of sputtered titanium oxide thin films

The electrochromic reaction of titanium oxide films prepared by r.f. sputtering was studied. Chronoamperometric experiments associated with transmittance spectra in LiClO4-propylene carbonate solutions were carried out and compared with the optical properties of titanium oxide films with different stoichiometries. It was verified that the colour changes produced by stoichiometry deviation and by electro-intercalation are similar, because the maximum absorption bands in both cases are centred at the same wavelength and the molar absorption coefficients are similar; these observations can be explained by the mixed valence theory deduced for non-stoichiometric metallic oxides.The analysis of the j vs. E and [d(OD)/dt]vs. E potentiodynamic profiles is an interesting method for studying the kinetic mechanisms of electrochromic reactions without interference from parallel reactions.

Influence of the anodizing procedure on the structure and the properties of titanium oxide films and its effect on copper nucleation

Thin oxide films are grown electrochemically on commercially pure titanium substrates. Constant potential (potentiostatic), constant current (galvanostatic) and initial constant current followed by constant potential (combined) growth modes are studied. The structure, the composition, the thickness, the electrochemical and the semiconducting properties of the oxide films are considerably influenced by the growth mode even if the final anodizing potential has a constant value.

Optical and electrical properties of titanium dioxide films with a high magnitude dielectric constant grown on p-Si by metalorganic chemical vapor deposition at low temperature

Metalorganic chemical vapor deposition of titanium dioxide (TiO2) on p-Si(100) using titanium isopropoxide and nitrous oxide via pyrolysis at relatively low (∼500 °C) temperature was performed to produce high quality TiO2/p-Si interfaces and to fabricate TiO2 insulator gates with a dielectric constant of high magnitude. Scanning electron microscopy shows that the surfaces of the TiO2 films have very smooth morphologies. From the x-ray diffraction analysis, the grown layer was found to be a polycrystalline film. Raman spectroscopy showed the optical phonon modes of a TiO2 thin film. The stoichiometry of the TiO2 film was investigated by Auger electron spectroscopy. Room-temperature current-voltage and capacitance-voltage measurements clearly revealed metal-insulator-semiconductor behavior for the samples of the Ag/TiO2/p-Si. The interface state density at the TiO2/p-Si interface was approximately high 1011 eV−1 cm−2 at the middle of the Si energy gap, and the dielectric constant determined from the capacitance-voltage measurements was as large as 73. These results indicate the TiO2 layers grown at relatively low temperature can be used for high density dynamic memory.

Photoelectrochemical Properties of Anatase and Rutile Films Prepared by the Sol‐Gel Method

Photoelectrochemical properties of titanium dioxide films in the anatase and rutile form which were prepared by the sol‐gel method were investigated. The effects of oxygen defects on photoelectrochemical properties were investigated by varying the reduction conditions such as atmosphere, temperature, and time. It is shown that (i) oxygen defects play a key role in photocurrent characteristics, (ii) oxygen defects drastically affect electroluminescence characteristics, and (iii) the electroluminescence intensity , infrared band, which peaked at 840 nm, is indicative of the degree of the reduction.

Structural properties of titanium dioxide films grown on p-Si by metal-organic chemical vapor deposition at low temperature

Abstract Metal-organic chemical vapor deposition of TiO 2 via pyrolysis using Ti (OC 3 H 7 ) 4 and N 2 O was investigated with the goal of producing TiO 2 epitaxial films on p-Si(100) substrates. X-ray diffraction analysis showed that the grown TiO 2 layer was a polycrystalline film. Auger depth profiles demonstrated that the TiO 2 /Si interface was relatively abrupt, and transmission electron microscopy verified the formation of an interfacial layer in the TiO 2 /Si interface and the formation of a polycrystalline TiO 2 thin film. These results indicate that the failure to form the TiO 2 epitaxial films originated from the formation of an interfacial amorphous layer at the initial growth stage.

The influence of oxygen partial pressure on the properties of DC reactive magnetron sputtered titanium oxide films

Titanium oxide thin films were grown on glass substrates by DC reactive magnetron sputtering at various oxygen partial pressures. The films were characterized using X-ray diffraction (XRD), X-ray photelectron spectroscopy (XPS), scanning electron microscopy (SEM) and optical transmittance spectra. The effects of the oxygen partial pressure on the structural and optical properties of titanium oxide films were investigated.

Comparison of the properties of titanium dioxide films prepared by various techniques

Fourteen university, government, and industrial laboratories prepared a total of twenty pairs of single-layer titanium dioxide films. Several laboratories analyzed the coatings to determine their optical properties, thickness, surface roughness, absorption, wetting contact angle, and crystalline structure. Wide variations were found in the optical and physical properties of the films, even among films produced by nominally the same deposition techniques.

Structural properties of titanium dioxide films deposited in an rf glow discharge

An rf glow discharge has been used to promote the reaction between titanium tetrachloride and oxygen in order to deposit thin films of titanium dioxide at low temperatures. Structural properties of the films have been studied as functions of deposition temperature (25 to 700 °C) and of substrate material (Si, sapphire, glass, NaCl, and Ti). Films deposited onto glass substrates were amorphous at temperatures less than 300 °C, anatase at 300 and 400 °C, a mixture of anatase and rutile at 500 °C, and only rutile at 600 °C and above. Films deposited on the other substrates showed similar behavior but the temperatures for specific crystalline forms differed for each substrate material. Deposition at low power densities and 400 °C resulted in large (∼5 μm) anatase crystallites in 1–2 μm films.

Preparation of suboxides in the Ti-O system by reactive sputtering

The preparation of non-stoichiometric TiO x films by reactive sputtering of titanium in an argon-oxygen plasma was studied in an r.f. diode sputtering system at 2 keV bias voltage. The properties of titanium oxide films deposited from oxidized and non-oxidized Ti targets were explored to determine the composition of the deposited phases. The mole fraction x of oxygen in the deposited films was determined from a combined analysis of deposition rate, substrate density and UV and IR spectra. The results indicate that phases with x = 0, x = 1.0 and x>1.6 (the Magneli phases and TiO 2) can be readily produced during reactive sputtering in argon plasmas containing an oxygen mole fraction in the range 0-0.15. The deposition of suboxide phases other than α-TiO δ, TiO 1±δ required stringent control of the processing variables.

A Method using T.E.M. and S.A.D. to Define the Structure of Anodized and Air Grown Oxide Films on Pure Titanium

We have determined the mechanical properties of aluminium oxide films by growing anodic films of known structure and thickness and relating these to natural oxide films. We are now investigating the mechanical properties of titanium oxide films, and to relate the stricture of anodic titania films to natural oxide films, we must, have more information than is contained in the literature.

Electrical and optical properties of titanium dioxide films

A method is described for producing insulating films of titanium dioxide by vacuum evaporation. Photomicrographs showing the growth of crystallites in the layer are presented, and X-ray and electron diffraction data are given. Sputtering regimes by means of which it is possible to produce compact layers of specific resistance 1013 ohm · · cm, dielectric strength 106V/cm, and dielectric constant of 30 are given. By investigating optical density spectra and temperature variation of electrical conductivity for these specimens values were obtained for the optical and thermal forbidden band widths in titanium dioxide; these were 4.2 and 3.9 eV respectively. It was found that insulating films of titanium dioxide were completely transparent over a wide range of wavelengths from 300 to 1000 mμ. Using the same investigations in layers with electrical conductivity greater than 10−13/ohm · · cm defects were discovered, which were connected with oxygen deficiency and gave three impurity energy levels in the forbidden band of titanium dioxide.

814. Electrical and optical properties of titanium dioxide films: T S Travina and Yu A Mukhin, Izv VUZ Fiz, 9 (6), 1966, 74–80 ( in Russian)

814. Electrical and optical properties of titanium dioxide films: T S Travina and Yu A Mukhin, Izv VUZ Fiz, 9 (6), 1966, 74–80 ( in Russian)