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[Display omitted] • The NiFe 2 O 4 nanoparticles are prepared in different annealing temperature using the facile hydrothermal method. • The microstructure parameters are determined by XRD and SEM images. • The BET and BJH analysis are used to determine the specific surface areas and the pore size distribution. • The optical band gaps of samples are investigated. • Correlation between optical, FTIR properties and microstructure parameters is studied. In this study, NiFe 2 O 4 spinel nanoparticles were prepared using the hydrothermal method and annealed at different temperatures of 550, 650, 750, and 850 °C. The crystallite size increased from 19.0 to 28.6 nm and the dislocation density decreased from 7.2 × 10 14 to 5.3 × 10 14 m - 2 . Also, the Fourier-transform infrared (FTIR) shifted absorption bands, ν 1 (594 to 616 cm−1) and ν 2 (400 to 422 cm−1), were observed. The FTIR-shifted absorbance bands have a good correlation with lattice microstructure parameters. Finally, the obtained results can provide useful information about the synthesis of spinel nanoparticles sensitive to lattice defects, using changes in physical properties. [ABSTRACT FROM AUTHOR]

Using black coatings and materials with high light absorbance that are capable of absorbing photons at visible and longer wavelengths is a very effective way to reduce unwanted stray light, also known as optical noise, within optical equipment. These lights can be greatly reduced to a reasonable level by functional and performable black coatings that are modified to absorb incident light as much as possible by their specific pigments. In the present work, several carbonaceous pigments were synthesized for the first time from wasteful materials and their optical properties in the visible and near‐infrared ranges studied. First, MCM‐48 and SBA‐15 were synthesized at different conditions and were then used as templates for carbonaceous products. SSS‐1 (the carbonic pigment synthesized by the mixture of sucrose and sodium silicate), SSS‐2 (the carbonic pigment synthesized by the mixture of sawdust and sodium silicate), and mesoporous carbon pigments (CMK‐3 and CMK‐1 with different levels of saturations) were synthesized. Finally, their structure, morphology, and optical properties were investigated by X‐ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE‐SEM), and Diffuse Reflectance Spectroscopy (DRS). The results indicated that the SSS‐1 pigment had a lower reflectance (below 1%) than carbon black (about 2.5%) in the visible region despite it being more cost‐effective than carbon black. The mesoporous pigments showed very high light absorbance in the visible region (about 2.5%). Compared with other black pigments, the CMK‐1 was the blackest synthesized material with a very low reflectance (about 0.05% in visible region), making it an ideal candidate as a super black pigment for reducing unwanted stray light within optical equipment. [ABSTRACT FROM AUTHOR]

Abstract: Indium tin oxide (ITO) thin films with composition of 9.42wt% SnO2 and 89.75wt% In2O3, and impurities balanced on glass substrates at room temperature were prepared by electron beam evaporation technique and then were annealed in air atmosphere at different temperatures from 350 to 550°C for 1h. XRD pattern showed that increasing annealing temperature increased the crystallinity of thin films and at 550°C, high-quality crystalline thin films with grain size of about 37nm were obtained. Increasing annealing temperature also increased conductivity of ITO thin films. Carrier densities (N D) and the flat-band potentials (E FB) were calculated by using electrochemical impedance spectroscopy (EIS). EIS results showed an enhancement in carrier densities and a shift of the flat-band potential to more positive values as the annealing temperature was increased. The UV–visible transmittance spectra were also confirmed that the annealing temperature has significant effect on the transparency of thin films. The highest transparency over the visible wavelength region of spectrum (93%) obtained at 550°C on annealing temperature. This result was equivalent with those values that have already been reported but with higher level (20wt%) tin-doped indium oxide thin films and also at 350°C substrate temperature. The allowed direct band gap at the annealing temperature range 350–550°C was estimated to be in the range 3.85–3.97eV. Band gap widening with an increase in annealing temperature was observed and is explained on the basis of Burstein–Moss shift. A comparison between the electron beam evaporation and other deposition techniques showed that the better figure of merit value can be obtained by the former technique. [Copyright &y& Elsevier]

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]