Solid State Phenomena Vols. 121-123

Abstract: Mg and Mg-Ni-based hydrides were mechanically milled with TiO2 nanoparticles to prepare Mg-20 wt.% Mg2Ni0.8Cr0.2-1.5 wt.% TiO2 composite. XRD results showed that the hydrides decomposed partly during ball milling. Under the combined effects of the catalyst of TiO2 nanoparticles, Mg2Ni0.8Cr0.2 alloy and Ni particles precipitated, and the mechanical driving force, the composite showed rapid hydrogen absorption/desorption kinetics. The absorption temperatures of the composite were greatly decreased and the rates of hydriding were increased. The composite can absorb 4.6 wt.% H at 373 K within 3 min and desorb 4.33 wt.% H at 573 K within 20 min.

Abstract: Well-crystallized nanopolycrystalline thin films of cubic strontium titanate, SrTiO3, have been prepared on the TiNi-deposited Ni substrate in Sr(OH)2 aqueous solutions at temperatures between 130 and 200°C under saturated vapor pressures. The microstructure and morphology of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photoelectrochemical properties of SrTiO3 thin films on TiNi-deposited Ni substrate were investigated on a three-electrode assembly. The grain sizes increased from 30 nm to 300 nm and the relative crystal intensity in XRD pattern increased with the reaction temperature. Its photocurrent increasesdfirst with the grain size, then decreased. When the grain size of the film is about 200 nm, the photocurrent is highest.

Abstract: A novel kind of ester has been synthesized as the ligand to prepare the PbS nanocrystals (NCs). When Pb(acac)2 (lead acetylacetonate) was used as the lead source, the (200) crystal plane of the ester capped PbS NCs became preponderant during the coarsening process along with the reduce of the contents of sulfide source. The ester ligand was stable and led to the formation of high quality PbS NCs. The broad XRD diffraction peaks are typical of nanosized particles. The HRTEM images showed well-defined, near monodispersed cubic particles.

Abstract: Mesoporous silica particles doped with iron was prepared with a novel method. Nitrogen adsorption-desorption test indicated that the BET surface area decreased with the increasing of iron doping amount. Small-angle X-ray diffractometry (SAXD) analysis showed that more iron dopant gave rise to less orderly structured product. FITRanalysis were all carried out to study the iron valent and distribution state in the as-made mesoporous silica particles.

Abstract: A unified model is developed for the finite size effect on the glass transition temperature of polymers Tg(D) where D denotes diameter of particles or thickness of films. In terms of this model, Tg(D) depends on both the size and interface conditions. The predicated results are consistent with the experimental evidences of polystyrene (PS) and poly (methyl methacrylate) (PMMA) films and nanoparticles with different interface situations.

Abstract: Nanocrystalline ZnO powders, whose crystalline sizes were 14.3, 21.2, 24.1, and 35.3 nm, respectively, were prepared by homogeneous precipitation process. Nanocrystalline ZnO powders were characterized with powder X-ray diffractometer (XRD), transmission electron microscopy (TEM) and X ray photoelectron spectroscopy (XPS). The performance of desulfurization of H2S at room temperature was investigated. Results demonstrated that the smaller the size of nanocrystalline ZnO, the darker the color of desulfurization products would be, which was more similar to the characteristics of multi-sulfide results, indicating that the mechanism of desulfurization of nanocrystalline ZnO was not the same as that of the analytical pure ZnO. Nanocrystalline ZnO improved the performance of desulfurization of H2S at room temperature, and the activity time of nanocrystalline ZnO (14.3 nm) for the desulfurization was 34 times that of analytical pure ZnO at absence of oxygen. When the oxygen was present in reaction, the accuracy of desulfurization was improved, in which H2S was prone to be oxidized into element S, and SO2 was not detected at outlet of the reactor.