Ordered semiconductor In2O3 nanowire arrays are uniformly assembled into hexagonally ordered nanochannels of anodic alumina membranes (AAMs) by electrodeposition and oxidizing methods. Their microstructures were characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A blue-green photoluminescence (PL) band in the wavelength range of 300–650 nm was observed in the In2O3/AAM assembly system. The PL intensity and peak position depend on the annealing temperature, which is mainly attributed to the singly ionized oxygen vacancy in the In2O3 nanowire array system.

Large-scale single-crystalline CdO nanowires have been successfully fabricated from the electrochemical deposition mixture film of Cd and Te at 450°C, and characterized by x-ray diffraction (XRD) powder, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM images show that these nanowires are uniform with diameters of about 40–60 nm, length up to several tens micrometres. XRD and selected area electron diffraction analyses altogether indicate that these CdO nanowires crystallize in a NaCl cubic structure. The growth mechanism of these nanowires is also proposed as vapour–liquid–solid mechanism, in which Te serves as a liquid-forming agent.

The sound absorption behaviour of an open celled aluminium foam fabricated by investment casting method was examined and correlated with the pore size, sample thickness and backing air gap depth in the present study. The foam shows low sound absorption coefficients at relatively low frequencies or with relatively thin sample thickness due to its 90% or higher open porosity. As frequency or sample thickness increases, the sound absorption is significantly enhanced. Furthermore, if the sample is backed with an air gap, the approximate periodical resonant absorption peaks emerge from the background and shift towards low frequencies with increasing the gap depth. It is also found that the present aluminium foam has even better absorption performance than polyurethane foam, with almost the same pore parameters as the former. The observation on the pore surface and further experiments demonstrate that the difference is attributed to rougher pore surface of the aluminium foam that makes the sound wave loss increase through enhanced friction between the air and the surface.