Abstract Nanocrystalline Titanium Research Articles

Evolution of Physical and Mechanical Properties of Nanostructured Titanium upon Annealing

Nanocrystalline and submicrocrystalline titanium are synthesized using the methods of severe plastic deformation by twisting and equal channel angular pressing with subsequent cold rolling. The microhardness, magnetic susceptibility, and electrical resistivity have maximum values in highly strained titanium. Annealing in the temperature range of 673–1123 K leads to restoration and recrystallization manifested in decreases in the microhardness by a factor of 2, in the magnetic susceptibility by 15%, and in the resistivity by 20%.

Synthesis and Characterization of Nanocrystalline TiO<sub>2</sub> Thin Films by Sol-Gel Dip Coating Method

Nanocrystalline titanium dioxide (TiO2) thin films have been prepared by dip coating method. The TiO2 thin films have been coated on glass substrate and annealed at 400, 450 and 500° C respectively. The X- ray diffraction pattern shows that TiO2 nanocrystalline thin films are of anatase structure and the grain size is found to be in the range of 20-35 nm. The annealed films have been observed to be nanocrystalline in nature and the crystallinity has been observed to improve on annealing. The surface topography of the films has been studied using atomic force microscope. The optical properties have been studied using transmittance spectra. The band gap has been found to lie in the range of 3.70 to 3.83 eV depending on the annealing temperature.

PHOTOCATALYTIC DEGRADATION OF AQUEOUS METHYL ORANGE USING NANOTITANIA LOADED Mo-MCM-41

Nanocrystalline titanium dioxide, TiO2 , is a well studied and commonly used material for photocatalytic applications. However, the control of particle size, monodispersity, large catalytic surface for sufficient adsorption of organic pollutants, recovery and recycle of TiO2 nanoparticles are challenging tasks. Hence in this work, titania has been introduced into the nanopores (2–10 nm size) of MCM-41 to produce stable nanoparticles of uniform size and shape. Further, the photocatalytic efficiency can be improved by lengthening the life time of the excited electrons/holes during photoreaction. This could be achieved by incorporating molybdenum in to the MCM-41 silica matrix in addition to titania loading. In the present study, the synthesis and the photocatlaytic efficiency of a new photocatalyst TiO2@Mo -MCM-41 (25 wt.% TiO2 loaded Mo incorporated MCM-41) are reported. Mo -MCM-41, with different ratios of Si to Mo ( Si/Mo = 25,50,75), is synthesized by hydrothermal method and loaded with 25 wt.% TiO2 using sol–gel method. The photocatalytic activity of the prepared samples was evaluated using methyl orange as a model organic compound. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and nitrogen adsorption–desorption isotherm (BET analysis) measurements were used to investigate the effects of the incorporated elements in the structure of MCM-41. It was found that the photodegradation ability of 25% TiO2 loaded Mo -MCM-41 was highly related to the amount of Mo atoms present in the sample with the optimum atomic ratio of Si to Mo being 50.

Microwave Hydrothermal Synthesis of Nanosize TiO<sub>2</sub>

Nanocrystalline titanium dioxide was synthesized by microwave hydrothermal (MH) using tetrabutyl titanate and normal butyl alcohol as start materials. The mixture solution of tetrabutyl titanate and normal butyl alcohol in 1:1.5 molar ratio was processed in a microwave hydrothermal digestion system at 200oC for 20 min to prepare nanosized TiO2 powders. The results showed that the microwave assisted reactions proceed at a faster rate than the traditional hydrothermal methods. The powder was heat treated at 500oC and the final products is ~20 nm in size and well dispersed.

Characterization and properties of anatase TiO2 film prepared via colloidal sol method under low temperature

Nanocrystalline titanium dioxide particles and films with anatase structures have been prepared via solvothermal method under low temperature. The products were characterized by X-ray diffraction and transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The optical properties were characterized in the ultraviolet-visible region by optical absorption measurement. The relationship between the optical band gaps and the structures was studied.

Facile Synthesis of Nanocrystalline Titanium Carbonitride via a Chemical Metathesis Route

Abstract Nanocrystalline titanium carbonitride (TiCN) was successfully synthesized at low temperature (450 °C) via a chemical metathesis route using the readily attainable TiCl4, CaC2 and NaN3 as source materials. X-ray powder diffraction indicated that the product was cubic TiCN with a lattice constant a = 4.252 Å. Transmission electron microscopy revealed that the crystals were composed of spherical particles with the diameter of 66 nm. X-ray photoemission spectra analysed that the atomic ratio was good agreement with the TiC0.4N0.6 stoichiometry. The possible formation mechanism was investigated.

Microstructural aspects of nanocrystalline titanium

Nanocrystalline titanium films were deposited over nickel substrate by physical vapor deposition process. Defect structures present in nanocrystalline Ti are discussed based on HRTEM observations. It has been suggested that nanocrystalline boundaries may relax by more than one process, leading to differences in atomic structure of boundaries. Structural vacancies appear to be the most predominant grain boundary relaxation mechanism in nanocrystalline Ti. Further, it is pointed out that solid state amorphization reaction can be strongly influenced by the high disclination content in nanocrystalline materials.