Rutile-type Titanium Research Articles

Rutile-type TiO 2 thin film for high- k gate insulator

We investigated rutile-type titanium dioxide (TiO 2) films for possible use as a high- k gate insulator. The TiO 2 thin films were directly deposited on Si substrates using a RF magnetron sputtering method with a sintered oxide target. A single phase of rutile-type TiO 2 whose dielectric constant of approximately 75 was obtained when the film was deposited in an inert gas atmosphere and annealed at 800 °C in an oxidizing gas atmosphere. The oxygen ions were deficient in the as-deposited film, and consequently, a sufficient oxygen supply was needed to crystallize the film to a single phase of rutile during the post-annealing. However, the interfacial SiO 2 layer between the TiO 2 and the Si substrate simultaneously grew thicker than 2 nm. As the interfacial SiO 2 grew, the leakage current was decreased and the equivalent oxide thickness was increased, in the Au/rutile-type TiO 2/Si capacitor. Therefore, we concluded that the growth of the interfacial SiO 2 layer thicker than 2 nm is inevitable to form the single phase of rutile-type TiO 2 and to decrease the leakage.

A Study on the Adsorption Characteristics of Orthophosphates on Rutile-Type Titanium Dioxide in Aqueous Solutions

Rutile-type titanium dioxide is widely used as a pigment for paint, coating ink, paper, plastic products, and cards because of its very whiteness and outstanding hiding property. It has two weak properties to be improved, however, one being its coagulation in compounding and the other its decreasing whiteness owing to poor heat resistance. To solve these problems, a study on the treatment of titanium dioxide surfaces by adsorption technology has been performed. Experiments have been carried out to establish the adsorption isotherms of orthophosphates on titanium dioxide and to investigate the effect of organic solvents on adsorption. It is shown that the adsorption isotherms vary with pH. A Freundlich adsorption isotherm is suitable for the acidic and basic regions, while a Langmuir adsorption isotherm is suitable for the region of pH 5–8 where a maximum adsorption has been achieved. In aqueous solutions containing organic solvents, the adsorption was strongest with aqueous solutions containing 1 wt% toluene and weakest with those containing 1 wt% ethanol. Among the alcohols used, the adsorption was strongest with the aqueous solution containing 1 wt% butanol and weakest with that containing 1 wt% ethanol, thus showing a correlation with the molecular weight of the alcohol.

Rutile-type titanium oxide films synthesized by filtered arc deposition

A filtered arc-deposition system was used to synthesize titanium oxide films by evaporating titanium ions in an oxygen environment. Fourier transform infrared spectroscopy and X-ray diffraction analysis show that the films exhibit the rutile-type structure. X-ray photoelectron spectroscopy reveals that a small amount of Ti2+ and Ti3+ still exists although Ti4+ is the main component in the films. The preferred orientation of the films is dependent on the substrate bias and oxygen pressure. Titanium oxide films with (101) and (002) preferred orientation were prepared by changing substrate bias and oxygen pressure. Ultraviolet–visible absorption spectroscopy was used to determine the optical band gap of the prepared films. The results show that the band gap of the films prepared under zero substrate bias is 2.39 eV. When the substrate bias is larger than −100 V, the optical band gap of the films is about 3.33 eV.

Synthesis and blood compatibility of rutile-type titanium oxide coated LTI-carbon

Titanium oxide films were synthesized by ion beam enhanced deposition, where the films were prepared by depositing titanium atoms and simultaneously bombarding with Xe(+) ions at an energy of 40 keV in an O(2) environment. The titanium oxide films exhibit rutile-type structure with (100) orientation and the O/Ti ratio is about 2:1. Ti(2+), Ti(3+) and Ti(4+) coexist in the films.In vitro andin vivo investigations were used to investigate the blood compatibility of titanium oxide films. The results show that the blood compatibility of rutile-type titanium oxide fi is better than that of low temperature isotropic pyrolytic carbon (LTI-carbon), which is widely used to fabricate artificial heart valve. It is thought that rutile-type titanium oxide coated LTI-carbon most probably becomes new biomaterial to fabricate artificial heart valves.

Study on the effect of ion beam bombardment during deposition on preferred orientation in rutile-type titanium dioxide films

Rutile-type titanium dioxide films, which exhibits tetragonal structure, were synthesized by ion beam assisted deposition with ion beam incidence inclined 45° to the substrate. The influence of ion bombardment during deposition on the texture of films was studied. A change of preferred orientation from (110) to (200) with increase of ion to deposited atom arrival ratio was observed in case Ne+ and Xe+ ion bombardment were used during film growth, respectively. It is found that in rutile type TiO2 films (110) plane exhibits the lowest surface free energy and crystallites with (100) orientation have the widest channel to ions when ion beam injects with direction 45° to the film. The preferred orientation of titanium oxide films from (110) to (200) is accounted for in terms of channeling of ions and surface free energy. When arrival ratio of ion to atom is low, crystallites with (110) orientation which has lowest surface free energy grow preferentially. As the increase of arrival ratio, the damage induced by ion bombardment compresses the growth of crystallites with shallow ion channeling. Then (200) preferred orientation is observed because of its deep ion channeling. Compared to the cases Ne+ is used, lower arrival ratio is required to change the orientation from (110) to (200) for Xe+ bombardment, because heavier ion leads to stronger radiation damage.

ルチル型TiO<SUB>2</SUB>/Al複合材料の強化材と母材との反応に及ぼす不純物元素の影響

ルチル型TiO<SUB>2</SUB>/Al複合材料の強化材と母材との反応に及ぼす不純物元素の影響

The Influence of Seed and SO<sub>3</sub> on the Formation of Rutile-type Titanium Dioxide from Sand-iron Slag

The residual slag after the refineing of sand iron has several and valuable components, such as SiO2, TiO2, Al2O3, Fe2O3, CaO, MgO, V2O3 etc.. When the slag is in glassy state, it easily dissolves in most mineral acids.In the present paper, the influence of seed on the formation of titanium oxide hydrates by the hydrolysis of titanium sulfate solution which is obtained by the sulfuric acid treatment of the slag and of SO3 on the formation of rutile-type titanium dioxide by heating of the hydrates are studied.The obtained results are as follow;(1) An effective seed in the hydrolysis of titanium sulfate solution in sulfuric acid solution is anatase-type hydrate.(2) The content of SO3 in the hydrates is reduced by the use of anatase-type seed in the hydrolysis.(3) Most of SO3 in the hydrates is removed by the washing with NaOH solution and Na-citrate solution (alkalic with NaOH).(4) In spite of the fact that the formation of oxygen vacancies in the oxygen structure of titanium dioxide accelerates the thermal transition of anatase to rutile, the hydrates containing SO3 convert more easily to rutile in O2 atmosphere than in air and N2 atmosphere. From this experimental result it is suggested that the rapid reduction of SO3 in titanium dioxide in O2 atmosphere promotes the thermal transition of anatase to rutile.(5) In the chromaticity coordinates, the whiteness of rutile-type titanium dioxide which was prepared from the slag in this study is approximately equal to that of a commercial rutile-type titanium dioxide.