Papers by Keyword: Rutile

Abstract: Short sulfate process was developed to produce rutile TiO₂ white pigment by using low concentration industrial TiOSO₄ solution as raw material via self-generated seeded thermal hydrolysis route. The concentration of TiOSO₄ solution had significantly influenced the structure and pigment properties of rutile TiO₂ white pigment. The samples were characterized by XRD, particle size distribution and pigment properties test. Appropriate concentration of TiOSO₄ was beneficial to promoting hydrolysis process in a proper way and obtaining favorable structure and high quality white pigment. The optimized concentration of TiOSO₄ solution was of 191.20 g/L.

Abstract: Rutile TiO₂ white pigment was prepared by self-seeded thermal hydrolysis route via short sulfate process from low concentration TiOSO₄ solution. Hydrolysis time had significantly influenced the structure and pigment properties of rutile TiO₂. The samples were characterized by XRD, particle size distribution and pigment properties test. The hydrolysis time had great influences on the hydrolysis rate, particle size distribution, crystal growth and particle aggregation of TiO₂, eventually determined the pigment structure and properties. The optimized hydrolysis time after second boiling point was of 2.5h. And the prepared rutile TiO₂ white pigment was with narrow particle size distribution and nice pigment properties.

Abstract: In this work, the effect of Pd addition on nanostructured TiO₂ powders is studied. The materials were obtained by the sol-gel method and characterized by XRD, Rietveld refinement, TEM, Raman and UV-vis spectroscopies. The crystal structure and the nature of the different TiO₂ phases were modified by varying the palladium/TiO₂ ratio: 0.01, 0.03, and 0.05. The XRD results revealed the presence of different combinations of TiO₂ (B), anatase, rutile and PdO phases as well as their coexistence in the different samples. The Rietveld analysis showed that the composition of the phases is rather affected by the amount of Pd added to the TiO₂ structure. The Raman spectroscopy confirmed the characteristic bands of the TiO₂ phases in the samples and their variation depending on the Pd/TiO₂ ratio. The TEM results indicated that the as-prepared samples displayed crystal sizes of nanometric order (˂ 80nm). The observed reduction of the band gap was also correlated with the combination of phases due to the palladium addition. All the Pd/TiO₂ samples showed a significant improvement in the elimination of 4-chlorophenol during the application of water treatment technology.

Abstract: The use of titanium and its alloys is currently considered very attractive for dental implants, with the improvement of physical properties, corrosion resistance and biocompatibility of them. These properties are attributed to the formation of titanium dioxide (TiO2) as a protective layer. The aim of this work is to understand the influence of time on heat treatment of CP-Ti Grade II at 850 oC. Heat treatments were performed for 5, 15, 30, 60 and 120 minutes. The response of titanium to oxidation at same temperatures and various timings has been investigated, in terms of wear resistance, surface morphology and oxide layer substrate adhesion. A variety of experimental and analytical techniques including scanning electron microscopy (SEM) and tribological testing have been used to characterize the resultant thermal oxidized surfaces. The results showed that oxygen diffused Ti structure can produce compact layer (TiO2), which exhibited good adhesion with the substrate at 30 minutes and 120 minutes of heat treatment.

Abstract: The objective of this work is to understand the influence of time on thermal oxidation of CP-Ti Grade II at 850 oC. Thermal treatments were performed for 5 minutes, 15 minutes, 30 minutes, 60 minutes and 120 minutes of isothermal stage. The response of titanium to oxidation at same temperatures and various timings has been investigated, in terms of layer thickness, phase evolution. A variety of experimental and analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM) and ball cratering test have been used to characterize the result of thermal oxidized surfaces. The results showed that oxygen diffused on Ti structure can produce a thick oxide layer with rutile (TiO2) between 3,50 and 10,34 microns, which exhibited good adhesion with the substrate.

Abstract: Nitrous oxide is generally emitted from industry through fossil fuel combustion thus giving adverse effect to human health and environments. Catalytic converter is the common method used to neutralize this hazardous gas but the high cost of precious metals had limited its application. Nanotitania could neutralize nitrous oxide by the photocatalytic phenomenon and the material is effective as it has small band gap energy and large surface area. In this study, we produced both anatase and rutile crystalline phase nanotitania from a local titanium mineral as the starting material. A significant improvement to the properties of our nanotitania is due to the present of naturally doped neodymium and zirconium ions that are present in the titanium mineral. This make the band gaps for both anatase and rutile to be smaller and effective in photocatalytic process. Three different nanotitania formulations, pure anatase, pure rutile and mixed rutile and anatase phases, were tried in the study and the results showed that all these three formulations were able to neutralize the nitrous oxide within a very short duration. Comparative study was then performed with a blank sample and the result shows there is still significant amount of nitrous oxide present after the 2 hours run.

Abstract: TiO₂ nanorods were successfully fabricated via hydrothermal method using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. The synthesized samples were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field-emission scanning electron microscope (FESEM). The study showed that as-prepared samples were the mixed crystalline phase of rutile and brookite. The weight fraction of rutile and brookite in the mixed-phase were accurately tuned by changing the concentration of CTAB. The morphology of prepared samples was TiO₂ nanorods with the diameter of 2530 nm and the length of 80150 nm. The samples for degradation of papermaking wastewater under ultraviolet light irradiation showed better photocatalytic activity than the commercial Degussa P25. HRT-3 prepared from CTAB: TBT molar ratio of 0.48 exhibited the highest photocatalytic activity, achieving 47.2% COD_cr removal rate and 89.5% chroma removal rate under irradiation 12 h.

Abstract: X-ray photoelectron spectra of TiO₂:Fe are measured. Electronic structure and magnetic properties of rutile doped by iron are calculated in frames of the coherent potential approximation. The main experimental spectral features of TiO₂:Fe such as heterovalent cation substitution (Fe³⁺→Ti⁴⁺), decreasing of the band gap value and appearance of additional features at the bottom and top of X-ray photoelectron spectra of valence band in comparison with those for undoped TiO₂ are described.

Abstract: The effects of sintering temperatures on phase behavior of products from rutile and quartz by aluminothermic reduction nitridation (ARN) were investigated in this study. The crystalline phase and morphology of the samples were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), respectively. As the temperature was 1200 oC, the phases were corundum, TiN, Si and a small amount of cristobalite. Mullite were initially observed when it reached 1300 oC. A small amount of Si₃Al₃O₃N₅ was detected when the temperature rose to 1400 oC. More corundum, TiN and Si₃Al₃O₃N₅ were obtained at 1500 oC. The quantities of TiN and corundum increased slightly at 1550 oC while Si₃Al₃O₃N₅ reduced. In addition, the microstructure of well-developed β-Sialon crystals was long columnar and the TiN particles distributed in the composites.

Abstract: This paper presents an investigation of the correlation between dielectric properties and microstructure and TiO2 crystalline-phase characteristics (rutile and anatase) in ZnO-TiO2-Nb2O5 system ceramics. Such ceramics were produced from powder mixtures of zinc oxide, niobium oxide and titanium oxide. Powder mixtures were compressed by pressing (100 MPa uniaxial and 300 MPa isostatic) and sintered at 1100, 1200 and 1250 °C. The sintered ceramics were characterized on the crystalline phases, density and microstructure and microwave frequencies. As for the microwave dielectric properties, dielectric constant, quality factor and thermal coefficient in the temperature range from-20 to 50 °C were measured. The results showed that the type of titanium oxide structure (rutile or anatase) causes influence on the type and quantity of crystalline phases in relative density of sintered ceramics and, consequently in their dielectric properties measurements.