Amal Lafy Al-Otaibi

Microstructural and Thermal Properties of Porous Aluminum Filled with Nanocrystalline Silicon

In this work, the structural, thermal and optical properties of porous aluminum thin film carried out with various intensities of the anodization current in sulfuric acid. The obtained pores at the surface are filled by nanocrystalline silicon (nc-Si) thin films deposited by plasma enhancement chemical vapor deposition (PECVD), which the role is to improving its optical absorption and thermal properties. The prepared sample is an assembly of three different media such as Al sample/ Porous aluminum layer filled with silicon (PAS)/ nanocrystallite silicon layer (nc-Si). The effect of anodization current on the microstructure of porous aluminium and the effect of the deposited silicon layer were systematically studied by atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy. The thermal properties such as the thermal conductivity (K) and thermal diffusivity (D) were determined by the photo-thermal deflection (PTD) technique, which is a non-destructive technique. Based on this full characterization, it is demonstrated that the thermal and optical characteristics of this films are directly correlated to their microstructural properties.

Excess conductivity analysis in YBa2Cu3O7−d added with SiO2 nanoparticles and nanowires: Comparative study

The effect of nanosized silicon oxide nanoparticles (denoted NP-SiO2) and nanowires (denoted NW-SiO2) additions during the final processing stage on electrical fluctuation conductivity of polycrystalline YBa2Cu3Oy (Y-123 for brevity) in the mean field region has been reported. Series of samples were synthesized in air using a standard solid-state reaction technique by adding nanosized entities up to 0.5 wt.%. Phases, microstructure and superconductivity properties have been systematically investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrical measurements. TEM investigations show the presence of inhomogeneities embedded in the superconducting matrix along with the presence of columnar defects in the case of SiO2 nanoparticles added samples, however nanowires tend to agglomerate by entangling with each other in the intergrain regions. The fluctuation conductivity was analyzed as a function of reduced temperature using the Aslamazov–Larkin model. Using the Lawrence–Doniach equations, the Ginzburg–Landau (GL) number (NG) and equations, the coherence length, the effective layer thickness, the lower critical field Bc1(0), the upper critical field Bc2(0) and the critical current density Jc(0) were estimated. It was found that the addition of an optimum concentration of SiO2 nanomaterials, that depends on the shape, effectively controlled the microstructure, the grains coupling and hence improved the physical properties of Y-123 compound.

High Thermoelectric Figure of Merit of Ag 8 SnS 6 Component Prepared by Electrodeposition Technique

A new thermoelectric material Ag8SnS6, with ultra-low thermal conductivity in thin film shape, is prepared on indium tin oxide coated glass (ITO) substrates using a chemical process via the electrodeposition technique. The structural, thermal and electrical properties are studied and presented in detail, which demonstrate that the material is of semiconductor type, orthorhombic structure, with a band gap in the order of 1.56 eV and a free carrier concentration of 1.46 × 1017 cm−3. The thermal conductivity, thermal diffusivity, thermal conduction mode, Seebeck coefficient and electrical conductivity are determined using the photo-thermal deflection technique combined with the Boltzmann transport theory and Cahills model, showing that the Ag8SnS6 material has a low thermal conductivity of 3.8 Wm−1K−1, high electrical conductivity of 2.4 × 105 Sm−1, Seebeck coefficient of − 180 μVK−1 and a power factor of 6.9 mWK−2m−1, implying that it is more efficient than those obtained in recently experimental investigations for thermoelectric devices.