Optoelectronic properties correlation to preparation of Au/La-oxide nanocomposite films

Gold nanoparticles were grown in La-oxide thin films deposited on quartz and silicon substrates. These films were annealed in pure hydrogen gas atmosphere at 300°C for different durations 15 min, 30 min, and 45 min and characterised by the X-ray fluorescence (XRF) and X-ray diffraction. The matrix La-oxide remained amorphous up to 400°C. The fraction of Au in La-oxide host material was 7 % molar with crystallite size of 6.8 nm. The Au NPs slightly grew by annealing in H2 gas at 300 K. The samples were investigated by UV-Vis-NIR absorption spectroscopy and dc-electrical measurements. They exhibit conducting properties and with H2 gas annealing, they showed red shifting of the bandgap with remarkable reduction of optical absorption coefficient by ~25 % and remarkable increase in electrical conductivity ~124 %. A global study of the influence of low-temperature post annealing in H2 gas on the electrical, structural, optical, and optoelectronic properties was conducted

Structure, microstructure and determination of optical constants from transmittance data of co-doped Zn0.90Co0.05M0.05O (M@Al, Cu, Cd, Na) films

ZnO, Zn0.95Co0.05O and Zn0.90Co0.05M0.05O (M@Al, Cd, Na, Cu) single phase films have been successfully synthesized by ultrasonic spray pyrolysis technique. Structural analysis by X-ray diffraction show that all the films have hexagonal wurtzite structure with an average crystallite size in the range of 19–25 nm. SEM analysis revealed that Cd and Na preserve the shape of nanopetals observed with ZnO or CoAZnO films, while the doping with Al or Cu promote the formation of dense films constituted of nanorods. By the application of Levenberg–Marquardt least square method, the experimental transmittance data were fitted perfectly with the transmittance data calculated via a combination of Wemple– DiDomenico model, absorption coefficient of an electronic transition and Tauc–Urbach model. The concentration of absorbing centres NCo and oscillator strength f of d–d transition of Co2+ ions are calculated from Smakula’s formula

Synthesis, characterization and photocatalytic behavior of Ag doped TiO2 thin film

Superlattices and Microstructures 85 (2015) 255–265In this study, structure, microstructure, optical properties and photocatalytic degradation of Rhodamine B (RhB) have been investigated in an aqueous heterogeneous media containing pure and Ag doped TiO2 nanostructures thin films which were prepared by a simple sol–gel route. Thermal analysis demonstrated that Ag content decreased the temperature of anatase-to-rutile phase transformation. X-ray diffraction analysis confirmed that the prepared nanostructures crystallize within anatase-type structure and that the dopant Ag ions were not fully incorporated within TiO2 host lattice, meanwhile both the refractive index and optical band gap were affected by Ag concentration. The photodegradation of Rhodamine B under UV-C radiation by using pure and Ag-doped TiO2 nanostructures showed that Ag played an important role in a significant improvement of the photodegradation efficiency and that the optimum content of Ag ions was found to be 0.5% molar rati