Indium oxide: copper oxide nanoflakes deposited by spray pyrolysis using an aqueous solution of chloride powders at 1:1 indium to cupper ions ratio. XRD measurement shows polycrystalline structures of mixed In2O3 and CuO phases. The crystallinity enhanced with increasing annealing temperature and an additional ternary phase of In2Cu2O5 appeared at 623 K. AFM measurements illustrate an obvious variation in the morphology of the sample surface with the variation of annealing temperature. The SEM image shows Thin walls connected in the irregular direction created by cavities that gave the sample a high surface area. The sensing measurements against NO2 gas confirmed the best sample was that prepared at 673 K, where the sensitivity increased while the response and recovery times decreased. The optimum sensitivity appeared at 473 K operating temperature is 55%.

Heterostructure thin films of indium and zinc oxides (IZO) were prepared by spray pyrolysis from an aqueous solution of the precursors at different substrate temperatures (TS). The polycrystalline structure of bixbyite appeared at a low temperature. The crystallinity was enhanced with the emergence of the zinc oxide phase. By increasing the TS to 623 K, the crystallite size was increased. SEM images reveal that the deposited sample at 523 K is composed of irregularly shaped nanoparticles with a lack of links. Increasing the TS to 573 K increases the average particle diameters, and the particles appeared as polyhedrons well connected with cavities between them, which candidates for gas sensing applications. Increasing TS to 623 K resulted in the particles merging. NO2 gas sensor results confirmed the enhancement of IZO sensitivity performance at 573 K. Keywords: Gas sensor, thin film metal oxide, spray pyrolysis, In2O3– ZnO

Nickel-doped Tin dioxide (NSO) nanostructured thin films were deposited using chemical spray pyrolysis at 450°C at various spray rates. The structural, morphological, and optical properties of the prepared nanostructured thin films were investigated to determine the effect of these parameters on the sensing properties of NSO film. X-ray diffraction revealed a polycrystalline structure with an increasing crystallite size as the deposition rate increased, which resulted in a gradual decrease in the bandgap. The FE-SEM images demonstrate that the deposition rate significantly influences the surface morphology and gas sensitivity performance. The sensitivity of the NO2 gas sensor fabricated employing NSO thin films increased as the deposition rate, and NO2 concentration was increased. At an optimal sensing temperature of 373 K, the maximum sensitivity was 120%, with a response and recovery time of 17 and 19 seconds, respectively.

Hydroxyapatite nanoparticles (HAp-NPs) were prepared using a precipitation route from an aqueous solution at a 1.66 Ca/P ion ratio and sintered at different temperatures. X-ray diffraction (XRD) was used to investigate the structural properties of the prepared films. Using a Field Emission Scanning Electron Microscope, the morphology of the surfaces was analyzed. Using Fourier Transform Infrared (FTIR) Spectroscopy, the surface's chemical composition and chemical bonding information were identified. The structural analysis shows that heating treatment reduced the broadening of diffraction peaks, enhancing the Hydroxyapatite phase crystallinity. No phase transition was observed as the sintering temperature increased, revealing the HAp phase's high stability. SEM micrograph images revealed a nanostructured foam-like structure that changed into a flake-shaped structure with diameters between 300 nm and 600 nm after heat treatment. FTIR spectroscopy results revealed that the heat treatment improved the crystallization of the developed HAp-NPs samples. Barrett-Joyner-Halenda (BJH) was used to determine the pore size of HAp NPs, whereas Brunauer-Emmett-Teller (BET) analysis was employed to characterize the surface area of the samples.

No abstract