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Rutile and anatase microcrystalline composites TiO 2 –(Ti 0.98 Si 0.2 )O 2 were successfully synthesized by auto-combustion method using urea, citric acid/nitric acid=0.6 and citric acid/nitric acid=1.2 as fuel. The prepared powders were characterized using optical and surface analysis methods. From the results of X-ray diffraction (XRD) patterns the rutile phase of the composite formed by one-step calcination. Micro size distribution function, surface morphology and electrical properties of powders were studied by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Ultraviolet–visible spectroscopy (UV–vis). The particle size distributions of composites were measured by Dynamic Light Scattering (DLS). From UV–vis spectra the quantum confinement effect is observed because the optical band gap of powders has a blue shift.

TiO2-(Ti[Formula: see text]Si[Formula: see text]O2 nanopowders (TS-NPs) with average particle size around 90 nm were successfully synthesized by controlled auto-combustion method by using citric acid/nitric acid (AC:NA) and urea/metal cation (U:MC). The structure of powders was studied based on their X-ray diffraction (XRD) patterns. The XRD of TS-NPs shows that rutile and anatase are the main phases of TS-NPs for AC:NA and U:MC, respectively. Particle size and histogram of nanopowders were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Optical properties of TS-NPs were calculated by Fourier transform infrared spectroscopy (FTIR) and Kramers–Kroning (KK) relation. Plasma frequencies of TS-NPs obtained from energy loss functions depend on fuels as a result of changes in crystal structure, particle size distribution, and morphology.

Using strontium–titanium salts precursor, nanopowders (STO-based-NPs) were successfully synthesized by controlled gel-combustion method. Citric and nitric acids in an optimum ratio were used as the fuel and oxidizer agents, respectively. After heat treatment at 850[Formula: see text]C, the crystalline structure of the products was investigated by X-ray diffraction. The effects of Ba and Ag dopants on particle size distribution were discussed by transmission electron microscopy (TEM). The optical and dielectric parameters such as energy band gap [Formula: see text], real and imaginary parts of refractive index, dielectric function and energy loss function of nanopowders have been investigated by UV–Vis and FTIR spectra. The band gap of SrTiO3 increased with increasing Ba, Ag and Ba–Ag. Different atomic radii of dopants are responsible for changing optical and dielectric parameters due to the altered orbital configuration of the lattice structure.