We have studied the influence of amorphous and crystalline substrate materials, such as a-Si and a-Si:H, as well as c-Si(111), (100), and hydrogen implanted c-Si(111) on the outdiffusion of Si through an evaporated Au thin film, and its subsequent oxidation in atmosphere. Using Auger electron spectroscopy depth profiling we observed that the SiO2 layer thickness d formed on top of the Au film strongly depends on the type of substrate material giving most enhanced Si outdiffusion from amorphous ones. The metastable phase AuxSi is detected on both interfaces between the Au/Si and the SiO2/Au layers. A temperature independent ratio, dH/d ≊ 2, is observed for the oxide layer thickness of substrates with and without hydrogen. This is a surprising result, which indicates the influence of nonthermodynamic effects, probably related to the surface structure of the semiconductor substrates and a strong influence of hydrogen. A model of the layer structure is developed, which permits the calculation of diffusion activation energies resulting in qHD ≂ qD ≂ 1.0 (eV) for the diffusing species on substrates with and without hydrogen, respectively.

Large amounts of solid wastes are discarded in the ornamental rocks industry. This work investigates the incorporation of ornamental rock-cutting waste as a raw material into an aluminous porcelain body, replacing natural feldspar material by up to 35 wt.%. Formulations containing rock-cutting waste were pressed and sintered at 1350 °C. The porcelain pieces were tested to determine their properties (linear shrinkage, water absorption, apparent density, mechanical strength, and electrical resistivity). Development of the microstructure was followed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The results showed that ornamental rock-cutting waste could be used in aluminous porcelains, in the range up to 10 wt.%, as a partial replacement for traditional flux material, resulting in a valid route for management of this abundant waste.

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The effect of copper doping on structural, electrical, and optical properties of zinc oxide films was evaluated. Copper-doped films (ZnO:Cu) were successfully deposited on a glass substrate by spray pyrolysis at doping levels of 0, 2.5, and 7.5 at% (ZnO, ZC2.5, ZC7.5). All films were polycrystalline, single-phase with ZnO hexagonal wurtzite structure. The films presented nanostructured crystallites, from 36.7 to 38.2 nm. Cu doping increased the electrical conductivity of the ZnO films; this change was proportional to the Cu concentration. The films presented high optical transmittance of 70-80% in the visible wavelength. The energy gap decreased upon Cu doping. The photoluminescence spectrum of all films displayed an intense ultraviolet emission and a weaker blue emission. The emissions shifted to lower wavelengths with increasing dopant concentrations. ZC7.5 presented the most promising properties for an application as transparent conducting oxide: intense optical transmittance and UV photoluminescence, also the lowest electrical resistivity.

Doped lanthanum chromite-based ceramics are the most widely used interconnector material in solid fuel cells (SOFC) since they exhibit significant electrical and thermal conductivity, substantial corrosion resistance and adequate mechanical strength at ambient and high temperatures. The disadvantage of this material is its high cost and poor ductility. The aim of this study is to determine the mechanical and oxidation behavior of a stainless steel (AISI 444) with a LaCrO 3 deposition on its surface obtained through spray pyrolisis. Coated and pure AISI 444 materials were characterized by mechanical properties, oxidation behavior, X-ray diffraction and scanning electronic microscopy. Results indicated that the coated material displays better oxidation behavior in comparison to pure stainless steel, but no improvement in mechanical strength. Both materials indicate that deformation behavior depends on testing temperatures.