BITS Faculty Publications
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Item Synthesis of nanoscale oxide scaffold on Nitinol surface using hydrothermal treatment(Taylor & Francis, 2015-04) Roy, BanasriNanostructured scaffolds were synthesized on the surface of equiatomic NiTi alloy (Nitinol) via hydrothermal treatment at 120 ± 1°C and 250 kPa using alkali (NaOH) solution of different strength. The scaffolds were found to be composed of intermingled nanopetals with varying morphology and phase content depending on the treatment time and alkali concentration. Single or mixed Ni3Ti3O, NiTiO3, H2Ti3O7 and TiO2 (anatase and rutile) phases were observed in the scaffold by X-ray diffraction study. Standard hemolysis testing showed significant biocompatibility improvement of the scaffolds grown in low strength alkali. Measurement of Ni release in the simulated body fluid (SBF) revealed that Ni release can be decreased from ∼60 μg L− 1 for the mechanically polished bare NiTi surface to ∼2·7 μg L− 1 for the scaffolded surface (scaffolds grown in low strength alkali).Item Synthesis of Mixed-Phase TiO2 Powders in Salt Matrix and Their Photocatalytic Activity(Taylor & Francis, 2016-05) Roy, BanasriThree mixed-phase TiO2 powders, containing ∼80 volume % anatase and ∼20 volume % rutile, were prepared from amorphous titanium hydroxide and three different salt matrices—pure sodium chloride, pure Na2CO3, and pure disodium hydrogen phosphate (DSP). Amorphous titanium hydroxide and salt mixtures were heat treated at 875°C in a rapid thermal annealing system for different times, according to the time–temperature phase transformation graphs. Time-dependent UV degradation of aqueous solutions of methylene blue dye (15 ppm) in the presence of mixed-phase powders was used to monitor the activity of the catalysts. Microstructural study of the powders by scanning electron microscope and transmission electron microscope combined with phase analysis by XRD and optical absorbance by UV-absorption spectroscopy indicated that the higher photocatalytic activity of the powder obtained from pure DSP salt could be explained by its smaller rutile particle size and anatase–rutile interparticle bonding.Item Synthesis of Al-doped Nano Ti-O scaffolds using a hydrothermal route on Titanium foil for biomedical applications(Elsevier, 2016-09) Roy, BanasriAl-doped and undoped Ti-O nanowire scaffolds were fabricated on the surface of titanium foil via a one-step hydrothermal reaction in the presence of an alkali solution at 120±1 °C temperature and at 15 psi pressure. Grazing Incidence X-Ray and electron microscopy analyses confirmed that the phase composition, length and diameter of the nanowires depend on alkali concentration and reaction time, and the Al doping. Whereas, Al doping retarded the oxide phase formation and transformation rate and changed the morphology of the nanowires. Preliminary hemolysis test showed better biocompatibility of the Al-doped scaffolds compared to the undoped ones.Item Investigating the effect of dopant type and concentration on TiO2powder microstructure via rietveld analysis(Elsevier, 2018-02) Roy, Banasri; Rao, N.V.M.The influence of dopant types (anion: Cl and F; cation: Fe and Zn) on the phase transformation, crystallite size, lattice parameters, and lattice strain of TiO2 powder is investigated by Rietveld refinement of X-ray powder diffraction (XRD) data. Undoped and doped powders are synthesized by using a sol-gel route and heat treated for different times and temperatures. In general, dopants diminish the phase transformation rate and decrease particle size (FESEM data support), but F doping demonstrates the strongest effect. Cation doping induces defects and distortion in the lattice and increases strain both in anatase and rutile phases, but anion doping enhances strain in anatase only. The decreasing order of the dopants inducing strain in anatase and rutile phases is observed as F > Zn10% > Cl > Zn5%> Fe10% > Fe5% ≈Zn1%>Fe1%>UD, and Zn10% > Fe10% > Zn5%>Fe5%> Zn1%> Fe1%> UD > Cl > F, respectively. This could be explained from EDX study, which shows that the anion dopants, irrespective of the amount, abandon the material at a treatment temperature ≥400 °C. This may create high defect density in anatase, influence phase transformation, and particle size. But, the high temperature ion mobility annihilates the point defects and shows less strain in rutile. Whereas, the cations assimilate in structure and show similar effects in both the phases.