Papers by Keyword: Anatase Phase

Abstract: TiO₂ and iron-doped TiO₂ were synthesized by sol-gel method. TiO₂ and 0.5 %mol Fe:TiO₂ were calcined at 500 and 800 °C for 3 h. The synthesized particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-VIS diffuse reflectance spectrophotometry (UV/DRS), scanning electron microscopy (SEM) and scanning electron microscope-energy dispersive X-Ray analysis (SEM-EDX). The XRD patterns of all samples that were calcined at 500 °C showed only anatase phase. On increasing temperature from 500 to 800 °C, the anatase phase transformed to rutile phase. For 0.5 %mol Fe:TiO₂, pseudobrookite (Fe₂TiO₅) phase was observed at 800 °C. The particles that contained rutile showed higher antibacterial activities against E. coli, B. subtilis, and S. aureus than anatase phase, under fluorescent irradiation.

Abstract: Dy₂O₃-TiO₂ nanocomposites with different weight percentage (0, 2, 4, 8 & 10)Dy were synthesized bysol-gel method and named as 0DT, 2DT, 4DT, 6DT, 8DT and 10DT. The structural properties of these nanocomposites are characterized by X-ray diffraction (XRD) and Raman spectroscopy. XRD results show that Dy₂O₃-TiO₂ nanocomposites have anatase phase with tetragonal structure. The average crystallite size of the Dy₂O₃-TiO₂ nanocomposites lies between 10 to 18 nm.Coupling of Dy with TiO₂ shifts the Raman band to higher wavenumber side indicating the creation of oxygen vacancies in the TiO₂ lattice.

Abstract: The major cause of surface and ground water contamination is due to effluent from dyeing industries. The discharged effluent chemicals inhibit light penetration into water bodies and some are considered to be carcinogenic. In this study, the photocatalytic decomposition of the synthetic dye, methylene blue was investigated in the presence of activated TiO2. The TiO2 sample was characterized by using XRD to analyze the presence of anatase and rutile phases. The dye degradation was monitored as a change in absorbance by UV-Visible spectrophotometer. The contributing factors towards dye degradation include both the dye concentration as well as the quantity of TiO2 used. Different quantities of TiO2 in anatase phase was taken and activated under UV radiation for 15 min. and subsequently coated on to TLC plates using 5% polyvinyl alcohol as a binding agent. This photocatalytic plate was kept in the methylene blue dye solution and exposed to sunlight. The results shows that 57% of the 30ppm methylene blue dye gets degraded within 75min., when exposed to UV activated TiO2 in presence of natural sunlight.

Abstract: Titanium dioxide powders were synthesized by ultrasonic-assisted hydrolysis reaction of titanium tetra-isopropoxide at the low-temperature. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD). The photocatalytic activity of samples were investigated by the degradation of methyl orange under UV light radiation (6W, λ= 352nm) at room temperature. The results indicated that the products were mainly composed of high homogeneity anatase phases, and the methyl orange degradation rate can reach more than 90% under ultraviolet irradiation 180min. The photocatalytic activity of the samples prepared by ultrasonic method is higher than that of the samples prepared by conventional hydrolysis method.

Abstract: TiO₂ thin films with good performance have been prepared by R.F. magnetron sputtering method on glass substrates. Surface morphology and UV absorption spectrum have been studied by XRD, SEM and UV-Vis scanning spectrophotometer. The influence of annealing temperature has also been discussed. The results show that, the films without annealing process present amorphous structure, the defects density of interior fiber is high and the structure is loose. With the rise of annealing temperature, the grain size increases, porosity decreases, and compactness is enhanced, at the same time, the film turns from anatase phase to rutile phase, quantum size effect is significant, surface energy reduces and absorb edge has red shift.

Abstract: The aim of the present study is to synthesize Fe3+-doped TiO2/3SnO2 powder and evaluate its antibacterial performance coated on polyvinylchloride films for fresh food packaging. Fe3+-doped TiO2/3SnO2 nanoparticles were prepared as a photocatalyst through the sol-gel method with concentrations of 0.3-1.2 mol% and a calcination temperature of 400°C. It was found that calcination temperatures strongly affect the phases and phase transformation of TiO2. According to XRD analysis, the anatase crystalline was formed at the calcination temperature of 400°C. In the present work, the photocatalytic performance was determined through methylene blue degradation. The antibacterial activity against Salmonella typhi was investigated with a vitro test, from which the mixture of conidial suspension and Fe3+-doped TiO2/3SnO2 powder was added to Nutrient agar (NA) plates under UV and visible light irradiation, respectively. It was found that Fe3+-doped TiO2/3SnO2 nanoparticles enhance photocatalytic activity and bacterial inactivation efficiency. In addition, Fe3+-doped TiO2/3SnO2 thin films can destroy the cell walls of bacteria within 240 min. Furthermore, the disinfection efficiency of TiO2/3SnO2/0.5 Fe3+ is greater under UV irradiation than it is under visible light.

Abstract: Dielectric ceramics have been widely investigated and used for microwave applications such as resonators and filters. The present study deals with the influence of sintering temperature on microwave dielectric properties of TiO2 ceramics with 10, 20, and 30 wt% ZrO2. Three compositions have been developed through mixing procedures and then tested for each sintering temperature: 1500 and 1400 °C. X-ray diffraction and scanning electron microscopy are carried out aiming to explain the ceramic behavior of each sample. The dielectric constants of different ceramics for both temperatures varied from 85.4 to 62.6, while their quality factor due to dielectric losses varied from 3110 to 1630. The Q decrease is attributed to the non uniform grain growth and to the obtained crystalline phases. The best microwave parameters were obtained for the ceramics sintered at 1400 °C, which can be applied in microwave circuits as dielectric resonators.

Abstract: Nanostructured titania coatings were prepared by atmospheric plasma spraying using commercial nano-powder. The effects of plasma forming gas H2 on microstructure and anatase content of coatings were examined by X-ray diffraction and field emission scanning electron microscopy. Photocatalytic properties of coatings were evaluated through a photo degradation of methylene blue in water solution under ultraviolet illumination. The results obtained indicated that the TiO2 coating was a mixture of anatase and rutile. The anatase content of coatings increased with increase in the flow rate of plasma forming gas H2. The content of anatase was as high as 60% in the as-sprayed coatings under optimal spray parameters. The photocatalystic property was improved by the content of anatase in coatings. It was found that all fabricated TiO2 coatings exhibited photocatalytic activity for the methylene blue test regardless of spraying parameters.