Showing papers on "Rutile published in 1969"

On a new family of titanium oxides and the nature of slightly-reduced rutile

Abstract: An electron microscope investigation of slightly reduced rutile (TiOx x= 1·986, 1·94) suggests the existence of a new family of ordered phases, probably TinO 2n-1 (n=15,…∼36), derived from rutile by crystallographic shear on planes parallel to {132}. Still smaller degrees of reduction (x= 1·995) introduce disordered shear planes parallel to {132} and {101}. Some comments on the mechanism of reduction are also included.

Interpretation of the Infrared Absorption Spectra of Stannic Oxide and Titanium Dioxide (Rutile) Powders

Abstract: Correlation of the absorption frequencies of powders of noncubic crystals has been achieved with the substantially different bulk‐mode lattice frequencies. A general Frohlich equation is derived which relates the ir‐absorption frequencies of a powder (consisting of “small” spherical particles embedded in a matrix), to the bulk‐mode lattice frequencies obtained from single‐crystal reflection spectra. This equation is applied to stannic oxide and titanium dioxide (rutile). By means of electromagnetic scattering theory, the transmittance of powdered stannic oxide and rutile is computed with use of the complex refractive index obtained from bulk crystals. The absorption peaks obtained in the scattering calculations compare well with experimental results and are consistent with the generalized Frohlich equation.

The polymorphism of the oxide Ti3O5

Abstract: The oxide Ti 3 O 5 has been prepared by reduction of TiO 2 (as anatase and as rutile) using Ti metal as reductant and vacuum sintering, or by using CO or H 2 as reductant The oxides produced, and also their oxidation products at 650 °C, were examined by X-ray diffraction Three forms of Ti 3 O 5 were characterized: 1 (a) a form designated as D-type, produced by the hydrogen reduction of anatase, which yielded rutile only on oxidation; 2 (b) a form designated as D'-type, produced by the hydrogen reduction of rutile, which had an apparently similar X-ray diffraction pattern to that of the D-type, but which yielded a mixture of anatase and rutile on oxidation; 3 (c) a form designated as M-type, produced by the vacuum-sintering of TiO 2 with Ti metal, which had a different X-ray diffraction pattern but which also yielded a mixture of anatase and rutile on oxidation Forms (a) and (b) are similar to the previously-claimed high-temperature form of Magn Eli; form (c) is similar to his low-temperature form; the transition temperature is slightly in excess of 100 °C The D'-type could be derived from the M-type The D-type could easily be changed into the M-type by cooling from 1350 °C under vacuum By annealing experiments, the D-type was shown to be a meta-stable form Some crystallographic considerations concerning the oxidation behaviour of the various polymorphs of Ti 3 O 5 are proposed, also a possible correlation with the various types of compounds having the pseudobrookite structure

Dielectric properties of normal, reduced, and specially reduced rutile (TiO2) single crystals at room temperature

Abstract: The variation of the dielectric constant (e′) and the dielectric loss (e″) have been studied as a function of frequency (102 to 1010 c.p.s.) for normal (as grown), reduced (heated in vacuum), and s...

Anisotropy of Diffusion in Rutile

Abstract: DURING the determination of diffusion parameters in the system Fe2O3–TiO2, marked anisotropy was found in the diffusion of Fe (III) into a rutile single crystal. Single crystals of rutile and haematite were cut and polished to one micron on successive diamond laps. The polishing treatment did not result in perfectly plane surfaces but in convex surfaces which gave contact between the crystals over only a relatively small area when they were brought into contact to form diffusion couples (Fig. 1). Annealing was carried out in a flowing oxygen atmosphere at 1,100° C for 20 h.

Chemical vapor deposition of dielectric thin films of rutile

Abstract: Thin films of titanium dioxide in the rutile form are deposited by chemical vapor deposition technique on a heated surface of a substrate by reacting titanium tetrachloride with oxygen, in the range of temperatures from 700 DEG to 900 DEG C.

Process for the manufacture of pigments of titanium dioxide in the rutile form

Abstract: A TITANIUM DIOXIDE RUTILE PIGMENT OF GOOD BRIGHTNESS, COLOUR, AND OTHER FAVOURABLE PROPERTIES IS MADE BY ADDING A RUTILE SEED TO A TITANIUM SULPHATE SOLUTION, HYDROLYSING THE TITANIUM SULPHATE TO A HYDROUS TITANIUM DIOXIDE GEL, ADDING FURTHER RUTILE SEED (PREFERABLY PREPARED IN A DIFFERENT WAY), AN ALKALI METAL COMPOUND, A ZINC COMPOUND, AND AN UNUSUALLY HIGH PROPORTION OF PHOSPHORIC ACID OR A PHOSPHATE, DRYING THE GEL CONTAINING THE ADDITIVES, AND CALCINING IT, PREFERABLY AT ABOUT 1000*C.

The Photoconductivity of the Titanium Dioxide Crystal

Abstract: The photoconductivity of titanium dioxide (rutile type) synthesized by the flame-fusion method was studied. The photoconductivity spectra showed three peaks. The first is the maximum response around the edge of the fundamental absorption of rutile; the second is the peak at 630 mμ (1.98 eV), and the third is the broad-band spectra in the near infrared region of 1.0–1.9 μ. From the facts that Fe is found by chemical analysis to be a major impurity in rutile, that the peak at 630 mμ is enhanced by the increase in Fe concentration from 0.006 mol% to 0.02 mol%, and that the infrared quenching band of photoconductivity is observed at 1.23 μ (1.01 eV) in Fedoped rutile, it is concluded that this peak at 630 mμ results from the excitation of the electron from the Fe3+ level. The broad-band spectra at 1.0–1.9 μ are enhanced by the reduction and are decreased by the oxidation of the crystal, so these excitation spectra are ascribed to lattice defects originating from the non-stoichiometry of TiO2. These defects ha...

Catalytic properties of TiO2 (anatase and rutile) in the conversion of ethanol and isopropanol

Abstract: 1. The conditions of precipitation of samples of TiO2 greatly influence their surfaces (from 6 to 80 m2/g), while the specific activity, especially for anatase, changes little. The activation energy of the dehydration of i-C3H7OH (36–39 kcal/mole) also changes little. 2. TiO2 (anatase) catalyzes chiefly the dehydration of i-C3OH7OH (92–97% propylene at 295–340°C). 3. TiO2 (rutile) results in a selective conversion of alcohols; with decreasing lattice parameters the dehydrogenating ability of rutile increases. Highly active rutile contains an increased amount of structural water per unit surface.

Electrophotographic Properties of Titanium-Dioxide Resin Dispersion Layers

Abstract: The electrophotographic properties of titanium dioxide-polymer dispersion layers were studied. The titanium dioxide powder of the rutile type and three well-known polymers, polyvinyl acetate, polyvinyl chloride, and polystyrene, were used. The measurements were done on the corona-charging properties, e. g., the resistivity and the capacitance of the layer, the rising gradient of the surface potential, and the fatigue effect of pre-illumination. The results make it clear that the analysis of an equivalent circuit can be applied to the interpretation of the rising gradient of the surface potential and to that of the dark decay to some extent. Moreover, it is found that the logarithm of the potential of the dark decay decreases proportionally to the cube root of the time at the initial step, while, at the next following step, it decays proportionally to the square root of the time. The mechanism of the dark decay of the surface potential is also discussed.

Kinetics of Crystallization in TiO2-Opacified Porcelain Enamels

Abstract: Three reactions occur when a TiO2-opacified porcelain enamel frit is fired: crystallization of anatase, crystalllization of rutile, and inversion of anatase to rutile The concepts of nucleation and growth theory have been applied to these three reactions to develop an overall kinetic law of transformation which predicts the concentrations of anatase and of rutile as function of the firing conditions This theoretical development has been found to agree with the results of quantitative X-ray studies