Effects Of Post-thermal Treatment Research Articles

Structural and Morphological Properties of Silica Extracted from Wild Oat Straw: Effect of Post-Thermal Treatment

Structural and Morphological Properties of Silica Extracted from Wild Oat Straw: Effect of Post-Thermal Treatment

Effect of cerium content and post-thermal treatment on doped anisotropic TiO2 nanomaterials and kinetic study of the photodegradation of formic acid

In this work, the design of cerium doped TiO2 nanomaterials with tuned structural and textural properties is reported. The influence of the cerium content of doped TiO2 solids (x=1 to 5wt%) on the photocatalytic degradation of formic acid using UV-A light was evaluated.The best photocatalytic activity was reached for 1wt% of cerium.The effect of post-thermal treatments was also herein highlighted by varying the calcination temperature between 400°C and 700°C for simultaneously doped- and cerium-free TiO2 samples. Characterization was performed by means of nitrogen adsorption–desorption isotherms at 77K, X-ray diffraction, Raman spectroscopy, Photoluminescence (PL) spectroscopy, and diffuse reflectance UV–vis spectroscopy. The presence of Ce limits the growth of TiO2 crystallite sizes during the post-thermal treatment and favors stabilization of the TiO2 anatase phase. The presence of cerium also increases the number of surface defects and transforms them to non-radiative centers able to capture the photogenerated electrons as observed by PL spectroscopy. This would leave photogenerated holes available improving consequentlythe photocatalytic activity for the oxidation of formic acid. Finally, a possible pathway mechanism is proposed to confirm the obtained results.

Functional Response of NiTi Elements for Smart Micro-actuation Applications

Shape memory alloys (SMAs) can be considered a good candidate for actuation applications in the current micro-technology field. In the micro-scale, the temporal response of the SMA actuators can be improved, because of faster cooling during the austenite-martensite transformation. One of the most investigated geometries for this purpose has been the snake-like arrangement, which allows high strokes with considerable forces to be obtained. In this work, SMA elements for micro-actuators were patterned by laser machining in a snake-like shape. Subsequent surface chemical etching was adopted to improve the functional properties of the micro-elements. Calorimetric analysis and thermo-mechanical response of 90 μm thick SMA elements were reported for the evaluation of their functional performances. Moreover, the effect of post-thermal treatment and grain orientation were also evaluated on the final performances.

Engineering stop gaps of inorganic-organic polymeric 3D woodpile photonic crystals with post-thermal treatment

A method is reported for improving the spatial resolution and engineering the stop gaps of the inorganic-organic 3D woodpile photonic crystals (PhCs). The approach is based on the two-photon polymerization (2PP) of an inorganic-organic hybrid material and a post-thermal treatment (PTT) process. The effects of PTT on polymerized 1D, 2D and 3D structures have been characterized. Ultimately, the feature size of the suspended rods has been reduced to approximately 33 nm and the spatial resolution of inorganic-organic 3D woodpile PhCs has been improved from approximately 150 nm to approximately 86 nm. The approach is also demonstrated as a powerful tool to engineer the stop gaps of 3D PhCs. In particular, a combination of PTT and the threshold fabrication technique leads to the stop gap of a 3D woodpile PhC that can be tuned over a large wavelength range of approximately 318 nm from the near-infrared to visible region.

Thermal treatment under reverse bias: Effective tool for polymer/fullerene bulk heterojunction solar cells

The effect of post-thermal treatment under reverse bias on the performance of bulk heterojunction photovoltaic cells based on poly[2-methoxy-5-(20-ethylhexyloxy)- p-phenylene vinylene] (MEH-PPV) and fullerene (C60) composites is investigated. The experimental results show that treated devices deliver increased short-circuit current density ( J sc) and conversion efficiency ( η p) values. Especially, for the device annealed under the bias of −6 V, the short-circuit current density ( J sc) and the conversion efficiency ( η p) are enhanced by a factor of 6 and 5.4, respectively. It is concluded that the enhancement of charge mobility induced by polymer chains modified orientation along the direction of electric field leads to a significant increase in the photovoltaic parameters.

Effects of post-thermal treatment on the properties of rf reactive sputtered ITO films

Indium tin oxide (ITO) thin film prepared by rf sputtering at various Ar–O2 mixtures, were annealed at several temperatures. The electrical, optical and structural properties of the film were systematically investigated before and after post-thermal treatment. The influence of a reactive gas (O2) on the sputtering rate of a metallic (indium/tin) alloy target was also investigated. The films were characterized by X-ray diffraction (XRD) measurement, scanning electron microscopy, and transmittance as a function of wavelength. The resistivity of 8.3×10−4Ωcm has been achieved for the film thickness of 250nm, deposited in pure Ar at room temperature (RT).

Effects of postthermal treatment and UV irradiation on the structure of titania-polyacrylate nanocomposites

The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO 2/polyacrylate nanocomposites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization were investigated, and the hybrid films were characterized by thermal gravimetry analysis (TGA), X-ray photoelectron spectrum (XPS), and atomic force microscopy (AFM). XPS data suggested that the prolongation of irradiation time and the postthermal treatment promoted titania formation, with the former affecting more remarkably. TGA data showed that TiO 2-hybrid films could upgrade the decomposition onset temperature ( T onset) as well as the temperature at which there is a maximum mass loss rate ( T max). AFM data demonstrated that the inorganic titania particles with a mean diameter of 25.26–28.84 nm were homogeneously distributed in the organic matrix.

Field emission characteristics of ruthenium dioxide nanorods

The effects of post-thermal treatment and rod diameter on the field emission (FE) properties ofRuO2 nanorod films are reported. The FE properties ofRuO2 nanorods with pyramidal tips have been studied on samples of two averagerod diameters, 48 and 35 nm. Both of them exhibit a transient behaviour inemission current under a fixed electric field. Thermal annealing at 400 and500 °C generally improves the FE characteristics in lowering the emission barriers of nanorods, asmanifested by a decrease in the turn-on field, the threshold field, the slope of theFowler–Nordheim plot, and the time-span of the transient period. Reduction inemission barrier appears to be particularly evident for the 35 nm nanorods. Yet500 °C annealing also degrades the emission current stability of 35 nm nanorods.The standard deviation of emission current density of 35 nm nanorods after500 °C annealing is around 44%. On the other hand, both specimens after400 °C annealing display a much more stable emission current density, whosefluctuations are 26% of their average values. The transient period isregarded as a consequence of gas molecules being desorbed from theRuO2 tips during emission, resulting in a reduction of the emission barrier. Thermal annealingweakens the bonding between the adsorbed gas and the tip surface, and facilitates the gasdesorption and electron tunnelling processes.

Effects of post-thermal treatment on preparation of surface microstructures induced by polarized laser on polyimide film

This paper reports experiments on the influence of the post-thermal treatment temperature of the polyimide (PI) film on laser-induced periodic surface structures (LIPSS). PI films were thermally treated at different temperatures ranging from 100 to 270 °C. The degree of imidization, the glass transition temperature and the surface roughness of polyimide films increased with the increase of the thermal treatment temperature. LIPSS were obtained on PI films under the irradiation of a linearly polarized UV laser with a wavelength of 355 nm. The formation process and the configuration of LIPSS varied with thermal treatment temperature. The formation of LIPSS consisted of an incubation stage, a rapidly developing stage and a stable stage. The incubation stage prolonged when the sample was treated at a higher temperature. The periodicity of the ripples on films treated at a temperature above 150 °C displayed an obvious decrease as the laser fluence increased.

Effect of Post Thermal Treatment on the Impurity Charge Distribution of Selenium Cadmium Diode

The paper discusses the effect of post thermal treatment on impurity charge distribution of Selenium Cadmium diode. It is reported that the thermal treatment affects the impurity distribution profile near the junction. Abrupt, graded and hyperabrupt profiles are developed by thermal treatment at 35° C, 130° C and 215°C respectively.