Micro-structural, linear and nonlinear optical properties of titania nanoparticles.

TiO(2) (titania) nanoparticles were prepared by sol-gel method using titanium tetrachloride as precursor and calcined at 500°C (SA1) and 800°C (SA2). X-ray diffraction pattern of SA1 has mixed phases of anatase (17%) and rutile (83%) whereas SA2 has pure rutile (100%) TiO(2). From the X-ray diffraction peak profile analysis, the crystallite size, lattice strain, deformation stress and energy density value of TiO(2)nanoparticles were determined more precisely by Williamson-Hall method, uniform deformation model, uniform stress deformation model, uniform deformation energy density model and size-strain plot method. The calculated average crystallite size from uniform stress deformation model is 21 and 53nm for SA1 and SA2 respectively. From the FTIR spectra Ti-O vibrational frequency is observed at ∼530cm(-1). Using Tauc's relation the direct bandgap of SA1 and SA2 is calculated from UV-vis spectra as 2.75 and 2.95eV respectively. The excitation wavelength dependent photoluminescence has been investigated for 290 and 330nm as excitation wavelengths. It was observed that the band edge emission is decreased with respect to excitation wavelengths. The second harmonic generation efficiency (SHG) observed for centrosymmetric rutile TiO(2) is more comparable with KDP crystal.