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

TiO2 (titania) nanoparticles were prepared by sol-gel method using titanium tetrachloride as precursor and calcined at 500 degrees C (SA1) and 800 degrees C (SA2). X-ray diffraction pattern of SA1 has mixed phases of anatase (17%) and rutile (83%) whereas SA2 has pure rutile (100%) TiO2. From the X-ray diffraction peak profile analysis, the crystallite size, lattice strain, deformation stress and energy density value of TiO2 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 53 nm for SA1 and SA2 respectively. From the FTIR spectra Ti-O vibrational frequency is observed at similar to 530 cm(-1). Using Tauc's relation the direct bandgap of SA1 and SA2 is calculated from UV-vis spectra as 2.75 and 2.95 eV respectively. The excitation wavelength dependent photoluminescence has been investigated for 290 and 330 nm 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 TiO2 is more comparable with KDP crystal. (C) 2014 Elsevier B.V. All rights reserved.