Tag Archives: Crystal Size

Dependence of Optical Band Gap on Crystallite Size of TiO2 Thin Films Prepared Using Sol Gel Process (Published)

We report on a simple and robust analysis of the energy band gap and crystal size of anatase TiO2 thin films on doped Fluorine Tin Oxide (SnO2:F) prepared using sol-gel Doctor-blade method. The films had been annealed at rates of 1oC/Min, 2oC/Min, 1-step and referenced with as-deposited film, and the optical and structural properties characterized using UV-VIS spectrophotometer and X-ray diffraction (XRD), respectively. The films had a refractive index which was noted to depend on the annealing rate consistent with Cauchy’s relation. An optical band gap of , , , and  was measured on the as-deposited, 1-Step, 2oC/Min and 1oC/Min annealing, respectively. Optical conductivity was highest in the UV region and diminished sharply in the visible region in all the annealed samples. The as-deposited film exhibited a diminished optical conductivity in the visible electromagnetic field due to high density of charge trapping sites resulting to negligible interaction of the film molecules with the applied electric field. The XRD spectra revealed thermal enhancement in crystallinity, with the crystallite sizes of ,  and ,  for 1-step annealed,  2oC/Min and 1oC/Min, respectively. The broadened XRD spectrum of the as-deposited film is attributed to the presence of dangling bonds that act as trapping sites. Comparison of the measured values of the optical band gap with simulation from SCOUT at low annealing rates (2oC/min and 1oC/min) was found to decrease with enhancement in crystallite size, indicating a reduction in porosity and improvement in both densification and crystallinity of the films.

 

Keywords: Crystal Size, TiO2, band gap, photon energy, refractive index

The Structural Characterizations of Polymethel(Methaacrylate) Doped Nanoparticle Metal (Cu,Co,Fe) Thin Film by Using Nd-Yag Laser Ablation (Published)

The structural properties of PMMA doped with ( Cu , Co , Fe ) nanoparticls prepared by laser ablation were studied . In  this  research  the  polymethyl mehtacrylate  (PMMA)  was  dissolved  in chloroform   with (5%) concentration  to  form  homogeneous  solution.  PMMA  doped  with  (Cu  ,Fe ,and Co ( nanoparticale (NPs) prepared by Nd-Yag(532nm) laser ablation. The X-ray diffraction shows  that  the  structure  of  pure  polymer  film  have  an  amorphous  nature,  but PMMA  doped  with  (Cu , Co , Fe)  nanoparticles  are  polycrystalline  structure.  The  results indicate that there are a shifting and reduction in positions of peak intensity as compared with the pure (Cu , Co ,Fe) nanoparticles and there are generated some new peaks appear. The AFM examination reveal to reduction in average nanoparticle diameter after doping with NPs metal (Cu , Co , Fe ) . The FT-IR  examination appear some transmittance band after doping with NPs metal (Cu , Co , Fe ) 

Keywords: Afm, Cobalt, Copper, Crystal Size, Doping, FTIR, Iron, Nanoparticle, Polymethyl Mehtacrylate (Pmma), Xrd