Papers by Keyword: Rutile

Abstract: A non-aqueous synthesis technique of room temperature curable titania ink, screen printed on flexible BoPET film for printed electronics applications is reported. The phase evolution of rutile titania powder, formulation of a fast curing titania ink, as well as the microstructure and dielectric properties of printed pattern are discussed. In terms of ease of synthesis, cost effectiveness and faster curing time, the developed ink is found to be advantageous over water based dielectric inks.

Abstract: Titanium oxide (Ti-O) films were prepared by low-voltage (i.e., 5-15 V) anodization of titanium plate in different hydrochloric acid (HCl) concentrations. Phase composition and surface microstructure of the anodized sample were investigated through XRD and SEM characterizations. Samples anodized at 15 V and in 0.6, 1.5 and 3.0 M HCl concentrations show higher amount of crystalline TiO₂ (i.e., anatase and rutile) phases as compared to other anodizing conditions. The three samples show open pores microstructure on the anodized surface. Samples anodized at lower voltages and in low to medium HCl concentrations also produce loosely bonded amorphous Ti-O granules on top of the crystalline TiO₂ phases. After annealing these samples at 400 or 600°C in air, further oxidation occurred on the anodized surface particularly at pores, contribution to slight increase in the crystalline phase. It suspected that the presence of amorphous Ti-O granules on top of crystalline TiO₂ phases at initial anodizing stage, hindered movement of OH^- and Cl^- anions onto the anodized surface, thus inhibited further growth of the crystalline TiO₂ phases.

Abstract: Phase transformation of TiO₂ (titanium dioxide) nanoparticles has been analyzed by observing the effect of NaCl addition to the anatase-to-rutile phase transformation. NaCl is one of key points in the transformation of rutile. Co-precipitation method was employed in which TiCl₃ as precursor was reacted with HCl 2M and subsequent NH₄OH. Three methods were studied, namely solution without NaCl addition (TiCl₃ + HCl + NH₄OH) as control solution subjected to route A (TiCl₃ + HCl – NaCl– NH₄OH – heated at 600°C for 5 hours) and route B (TiCl₃ + NaCl – heated 200°C for 5 hours – NH₄OH – heated 200°C for 6 hours). Route B was subjected to heating at 200°C. The results show that without NaCl it enhanced the crystal growth of the rutile embryos allowing the ease of rutile formation at 600°C, while route A promoted the transformation of brookite and hindered anatase-to-rutile transformation as indicated by the presence of anatase at 1000°C. On the other hand route B is potential for being further explored.

Abstract: Dye sensitized solar cells based on TiO₂ nanorod suffers from low dye loading and poor light scattering ability, both of which obstacle the improvement of energy conversion efficiency. In this paper, we have successfully synthesized TiO₂ rutile nanostructures with tunable morphology on FTO substrates with a one-step hydrothermal synthesis by changing the Ti concentration in the precursor solution. Three different photoanodes, namely, nanorod layer, nanorod layer with flower-like clusters and nanorod layer with densely packed spheres, are obtained without using any surfactants. The photoanode of nanorod layer with densely packed spheres exhibits improved dye loading and enhanced light reflection from 600-800 nm. DSSCs based on such a photoanode exhibits an energy conversion efficiency of 4.08%, achieving a nearly three-fold enhancement compared with dye sensitized solar cells based on TiO₂ nanorod array.

Abstract: The study was focused on the performance of rutile addition in the glaze for antibacterial application. Rutile powder in micro size (<5µm) (at different composition 5 wt%, 7 wt%, 9 wt%, 10 wt% and 15 wt%) were added in the glaze. Glazing was performed by dipping method for 10 seconds. Glazed tile was then sintered at 1200°C for 1 hour. Characterizations used to observe the properties of produced tiles were physical observation, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Optimum sample was undergone an antibacterial test towards E.coli.

Abstract: In this study, TiO₂ nanoparticles were successfully synthesized using sol-gel technique by employing different mixing routes. The nanoparticles were characterized for field emission scanning electron microscopy, energy dispersive X-Ray spectroscopy, Fourier transformed infrared, Raman spectroscopy, x-ray diffraction and ultraviolet visible spectroscopy. It is apparent that different mixing sol-gel route significantly influenced the morphology, crystallite structure, particle and crystal size and band gap of TiO₂, under similar molar ratio. The differences in physicochemical and optical properties of synthesized TiO₂ greatly influenced its photocatalytic activity in reactive black 5 dye degradation. In overall, mixed crystal structures of anatase and rutile showed better photocatalytic activity for the degradation of reactive black 5 dye due to a narrower band gap, as opposed to single phase TiO₂.

Abstract: Resin impregnated wooden furniture is one of the major sources of formaldehyde in homes from the use of urea-formaldehyde and phenol-formaldehyde resins as adhesives. Indoors, emission of formaldehyde is accelerated by heat and humidity. Dehumidifiers and air conditioners are recommended to improve indoor air quality but the maintenance is costly and relative humidity in some areas are difficult to control. Due to small band gap energy and large surface area, nanotitania could neutralize formaldehyde gas by photocatalytic phenomenon. A study was carried out to investigate the formulations of pure anatase, pure rutile and mixed rutile and anatase phases which can neutralize formaldehyde within a short time. Comparative study was then performed with a control and the result showed that for the control, there are still significant amount of formaldehyde present after running the sample for one hour.

Abstract: A chemical inducing process was developed to prepare titania-mica pearlescent pigment. MnO₂ was used as crystal inducing promoters, a transformation between antase and rutile titania-mica pearlescent pigment was found by calcining at 800°C for 0.5 h. The mass ratio of mica to MnO₂, pH value, temperature and dripping rate of MnO₂solution and TiOSO₄was studied. The crystalline form of titania-mica pearlescent pigment was measured by XRD.

Abstract: Using unconcentrated industrial TiOSO₄ solution as raw material, rutile TiO₂ white pigment was prepared via the self-seeded thermal hydrolysis sulfate process. The effects of pre-adding water volume ratio on the hydrolysis process and pigment properties of the TiO₂ white pigments were investigated. The samples were characterized by XRD, particle size distribution and pigment properties test. The pre-adding water volume ratio had great effects on the quantity and active of seed crystal, hydrolysis process, eventually determined particle size distribution and its pigment properties. The optimized pre-adding water volume ratio was of 0.22. The as-prepared rutile white pigment was with appropriate particle size, narrow particle size distribution and good pigment properties.

Abstract: Rutile surface has been modeled in order to study its electronic properties as well as to determine its surface chemical reactivity. There have been constructed 10 different rutile structures, from a 6 atoms cluster (for the smallest) to a 356 atoms cluster (for the biggest). It was calculated for each cluster some physical parameters which are related to the electronic properties, such as work function, band gap, and density of states (DOS), in order to analyze the tendency of the cluster properties with the increase of atoms. From the data obtained, it was determined the Electronic Unit Cell (EUC), which refers to the modeled structure for what the electronic and reactivity properties of the system does no change, from clusters with different number of atoms. From the rutile EUC cluster it was determined its band gap with a value of 3.28 eV, which agreed with the experimental value of 3.0-3.1 eV. Furthermore, it was performed a reactivity surface study, which comprised the analysis of reactivity descriptors such as ionization potential, electronic affinity, total hardness, electronic chemical potential, electrophilicity and electronegativity. All theoretical calculations were performed using the semiempirical PM7 included in the 2012 version of MOPAC and the surfaces were modeled from crystallographic data.