Corrosion behaviors of thermally grown oxide films on Fe-based bulk metallic glasses

Oxide films formed on the surfaces of Fe-based bulk metallic glasses in the temperature range between 373 K and 573 K were characterized and their effects on the corrosion behaviors were investigated by microstructural and electrochemical analysis. The oxide film formed at 573 K is iron-rich oxide and it exhibits an n-type semiconductor at a higher potential than 0.35 V and a p-type semiconductor at a lower potential than 0.35 V. Capacitance measurements show that the donor density decreases with the increase in oxidation temperature, while the thickness of the space charge layer increases with the oxidation temperature rising. The result of immersion tests shows that the mass loss rate increases with the oxidation temperature rising. Therefore, the correlation between microstructure and corrosion resistance needs to be proposed because the corrosion resistance is deteriorated with the development of the oxide films.

Optical Transmission Spectra of Anodic Aluminum Oxide Membranes with a Dual Layer-by-Layer Structure

By adjusting the anodization voltage periodically in the process of electrochemical oxidation of Muminum and subsequent chemical etching, anodic aluminum oxide membranes with a dual periodic layer-by-layer structure are prepared. Optical transmission spectra analyses prove that the dip position is dependent on the thickness of the layer and can be easily adjusted by the anodization voltage according to the Bragg-Snell formula. This result implies that the position and width of the stop band and the pass band in the visible and near infrared wavelength region can be designed and prepared arbitrarily. It is expected that these kinds of anodic aluminum oxide membranes may find applications in the fabrication of various optical devices.

Energy band engineering of Bi_(2)O_(2.33)–CdS direct Z-scheme heterojunction for enhanced photocatalytic reduction of CO_(2)

In this work,a Bi_(2)O_(2.33)–CdS direct Z-scheme heterojunction was fabricated based on energy band engineering.The Bi_(2)O_(2.33)core nanoflakes were first synthesized by electrodeposition which was followed by an annealing process to fabricate this heterojunction.Then the Cd S shell was deposited on Bi_(2)O_(2.33)nanoflakes utilizing the solution method,during which a suitable concentration of Cd Clsolution was used for forming a homogeneous and continuous integrated CdS shell.A space charge region and an internal electric field from CdS(+)to Bi_(2)O_(2.33)(-),which drove a direct Z-scheme charge transfer process,were formed at the interface.The Bi_(2)O_(2.33)–CdS exhibited excellent photocatalytic performance for CO_(2)reduction mainly attributed to the satisfactory photoinduced charge separation and transport efficiency in the direct Z-scheme heterojunction.The photocatalytic CO_(2)reduction ability of Bi_(2)O_(2.33)–CdS was significantly enhanced compared with single Bi_(2)O_(2.33)or Cd S,with a CO_(2)yield rate of ca.2.9μmol/(cm^(2)h)under a 300 W Xe lamp.The reduction of CO_(2)to CO_(2)demonstrated 94.0%selectivity.

Fabrication and properties of anodic alumina humidity sensor with through-hole structure

Through-hole structural humidity sensor was fabricated by radio-frequency magnetron sputtering deposition of gold electrodes on two sides of anodic aluminum oxide (AAO) membranes which were prepared by two-step anodization procedure at 0―5℃ and 40 V in 0.5 mol/L oxalic acid electrolyte. The investigation on the impedance at various humid conditions showed a linear relationship between im- pedance and relative humidity over the range of 12%―97% RH. Other excellent properties such as rapid response and good reproducibility were also obtained.

Thick-Film Negative-Temperature-Coefficient Thermistors with a Linear Resistance-Temperature Relation

The effect of the resistance R of Mn1.85Co0.3Ni0.85O4(MCN)thick-film negative-temperature-coefficient(NTC)thermistors on temperature T is studied carefully.Interestingly,the R–T relation is found to be decided simultaneously by the characteristic of the MCN oxide and the electrode structure of the NTC thermistor.For plane end electrodes,the R–T relation is nonlinear.However,for plane fork electrodes,the R–T relation can be linear.To clarify the intrinsic mechanism of the linear R–T relation,the electric field distribution in the MCN thick film is simulated.The obtained results suggest that the non-uniform electric field distribution between the electrodes is responsible for the R–T relation linearization.

Fabrication of porous alumina templates with a large-scale tunable interpore distance in a H_2C_2O_4-C_2H_5OH-H_2O solution

Highly ordered porous alumina templates with a large-scale tunable interpore distance (100―445 nm) have been successfully fabricated under an electric field of 40―180 V by modifying oxalic acid solution with adequate alcohol. The results under our experimental conditions show that the phenomena of burning and breakdown during the high-field anodization process can be avoided by adding a proper amount of alcohol to the oxalic acid solution. An excellent linear relationship between interpore distance and anodization voltage is obtained under 40―170 V, and the maximum anodization voltage that could be used to avoid burning and breakdown is 180 V.