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[Display omitted] • Effects of metal dopants on the optical, microstructure and gas sensing properties of In 2 O 3 films is investigated. • Among metal dopants, including Sn, Zn, Mn and Ag, silver metal shows better sensing results. • The correlation between the physical characteristics and gas sensing properties is studied. • 3% doping of Ag is an effective method to improve the electro-optical and gas sensing properties of In 2 O 3 films. • The effects of crystallite size, dislocation density, lattice strain and roughness on sensitivity is determined. Thin films of pure and Sn, Zn, Mn, and Ag-doped indium oxide (In 2 O 3) with a thickness of 150 nm are grown by co-deposition using thermal evaporation technique and annealed at 500 °C. The crystal lattice strain, dislocation density, optical band gap, surface roughness, and gas sensitivity of the films are studied. Comparison of AFM results shows that the Ag-doped In 2 O 3 has the highest roughness. The ethanol vapor sensing results demonstrate that 3% Ag-doped In 2 O 3 films have higher sensitivity at the operating temperature of 325 °C to 1000 ppm of ethanol vapor , due to the presence of more roughness and defects than other films. The response and recovery times of this sample at 1000 ppm ethanol vapor were 32 and 51 s, respectively. Finally, it is shown how 3% of metal impurities in the In 2 O 3 layer can affect the optical, microstructural, and gas sensing parameters of the samples, and also investigated the correlation between them. [ABSTRACT FROM AUTHOR]

In this study, the composed nanocrystalline ZnCo 2 O 4 and graphene quantum dots (GQDs) were prepared using the facile hydrothermal method. Various microstructure characteristics were specified using X-ray diffraction analysis approaches, including Williamson-Hall and Williamson-Smallman methods. The analysis of scanning electron microscopy, Brunauer-Emmett-Teller, and atomic force microscope were used to morphological characteristics and the pore size distributions of samples. Besides, the optical band gap was decreased by the addition of graphene quantum dots to the ZnCo 2 O 4 nanostructure. The greater crystallite size (45.0 nm) was accompanied by the smaller band gap (3.60 eV). The gas sensing investigations exposed that the coral-like ZnCo 2 O 4 /GQD composite nanostructures gas sensor exhibited high response (6.97–100 ppm), selectivity, and low detection limit (0.43 ppm) towards triethylamine. Moreover, enhanced gas sensing properties of coral-like ZnCo 2 O 4 /GQD composite nanostructures were observed when compared with coral-like ZnCo 2 O 4 nanostructures. These results can be attributed to their higher pore volume and diameter than nanocrystalline ZnCo 2 O 4. [ABSTRACT FROM AUTHOR]

In this work, in order to study the correlation between the microstructure and optical properties of the low symmetry materials, two different nanopowders i.e. TiO 2 (tetragonal) and NaTaO 3 (orthorhombic) are synthesized by the sol-gel and hydrothermal methods, respectively. Based on the active slip systems in rutile crystals, the contrast factors of dislocations are calculated numerically for TiO 2 and then the microstructure behavior is investigated in terms of annealing temperature using the whole powder pattern modeling method. The NaTaO 3 is crystallized in perovskite structure with unknown slip systems, therefore the behavior of its microstructure is investigated by the Rietveld method. Furthermore, UV–Vis and photoluminescence spectra were measured for two series samples to find the relation between the optical and microstructure peculiarities. [ABSTRACT FROM AUTHOR]

Similar to the single layers, the electrical and optical parameters of bilayer systems strongly depend on the crystallite properties (size, shape and distribution function) and the lattice defects of each layer. Moreover, the interactions and processes between the particles at the interface of two layers can affect directly the physical properties of bilayer films. In order to study the above subject, in this study two famous metal oxide semiconductors i.e. zinc oxide and titanium oxide are selected. The bilayer films are annealed at temperature interval between 400 and 600°C. The phase fractions, microstructure parameters and surface morphology of the films are studied as a function of annealing temperature, using the X-ray diffraction patterns and scanning electron microscope images which confirm the presence of two various ZnO components with different crystallite size and lattice strain. The effective optical band gap in addition to the refractive index of films are estimated as a function of the annealing temperature, crystallite size and density of defects. The gas sensing properties of films in the presence of ethanol gas are also studied as a function of time interval, gas concentration and operating temperature. Finally, the effects of X-ray diffraction analysis and scanning electron microscope results are investigated on the gas sensitivity of our bilayer films. [ABSTRACT FROM AUTHOR]