Synthesis and characterization of undoped and cobalt-doped TiO2 nanoparticles via sol–gel technique

TiO 2 nanoparticles doped with different concentrations of cobalt (4, 8, 12 and 16 %) were synthesized by sol–gel method at room temperature with appropriate reactants. In general, TiO 2 can exist in anatase, rutile, and brookite phases. In this present study, we used titanium tetra iso propoxide and 2-propanol as a common starting materials and the obtained products were calcined at 500 °C and 800 °C to get anatase and rutile phases, respectively. The crystalline sizes of the doped and undoped TiO 2 nanoparticles were observed with X-ray diffraction (XRD) analysis. The functional groups of the samples were identified by Fourier transform infrared spectroscopy (FTIR). From UV–VIS diffuse reflectance spectra (DRS), the band gap energy and excitation wavelength of doped and undoped TiO 2 nanoparticles were identified. The defect oriented emissions were seen from photoluminescence (PL) study. The spherical uniform size distribution of particles and elements present in the samples was determined using two different techniques viz., scanning electron microscopy (SEM) with energy-dispersive spectrometer (EDX) and transmission electron microscope (TEM) with selected area electron diffraction (SAED) pattern. The second harmonic generation (SHG) efficiency was also found and the obtained result was compared with potassium di hydrogen phosphate (KDP).