Advanced Materials Research Vols. 998-999

Abstract: The corrosion behavior of AZ81 magnesium alloy with the LPC addition has been investigated in this paper. The results show that with the addition of 1-5% LPC, the microstructure of AZ81 magnesium alloy is remarkably refined, and the spotted, high-melting point phase Al-RE intermetallic compounds is found in the alloy. The corrosion behavior of AZ81 alloy decreases firstly and then increases sharply with the increase of LPC addition. When the content of LPC is 2.5%, AZ81 magnesium alloy shows the lowest corrosion rate. The corrosion rates in 3.5%NaCl solution are always higher than those in 0.5%NaCl solution. The corrosion products from the surface are mainly composed of Mg (OH) ₂ compositions.

Abstract: Copper chalcogenide nanoparticles (NPs) represent a promising material for solar energy conversion and electrical charge storage. We showed that aqueous synthesis of high quality monodispersed high-chalcocite Cu₂S NPs is possible. Here, different thioglycolic acid (TGA) concentrations were employed in studies made to investigate the effects of stabilities ratio on particle morphology. It was found that the stabilizes concentration plays a key role in the synthesis of Cu2S NPs, the reaction rate is fast at low concentrations of TGA, and the size range is lager, while flower-like cluster with sizes of 30 nm were formed at high concentrations of TGA. Rapid availability of our results will provide valuable insight into the controlled growth of aqueous dispersions of ternary copper chalcogenide NPs, stimulating further studies of these materials in green energy conversion technologies and drug delivery applications.

Abstract: The enhanced dispersion strengthening of Sm in Mg-10Y-0.5Sm has been investigated by means of microstructure analysis and tensile tests. The results show that Sm addition improves the image of Mg₂₄Y₅ phase and causes the formation of fine and dispersed Mg₂₄Y₅ phase. Meanwhile, the dissolved Sm increases the thermal stability of Mg₂₄Y₅ phase and enhances its dispersion strengthening in the alloy. It leads to the increased tensile strength of the alloy at elevated temperatures.

Abstract: Well-dispersed, uniform Gd₂O₃:Eu³⁺ hollow microspheres have been successfully fabricated via a urea-based homogeneous precipitation method in the presence of colloidal carbon spheres as template, followed by subsequent heat treatment. The main process was carried out under aqueous conditions without any organic solvents, surfactants, or etching agents. The as-obtained Gd₂O₃:Eu³⁺ spheres with a spherical shape and hollow structure are uniform in size and distribution, and the diameters of the spheres and thickness of the shell are about 500 nm and 50 nm, respectively. The Gd_2O3:Eu³⁺ hollow spheres exhibit strong red emission corresponding to the ⁵D₀-⁷F₂ transition of the Eu³⁺ ions under ultraviolet excitation, which might find potential applications in the fields such as light-emitting phosphors, advanced flat panel displays, or biological labeling.

Abstract: With the aid of scanning electron microscope and energy spectrum analysis, the present thesis made a research on the fatigue fracture surface of AA 6A02 with corrosion damage as well as the effect of alloy element Si, Mg and the corrosion damage on the fracture process. Results indicate that the fatigue fracture surface is tough fracture with multiple fatigue sources. Pits introduced by corrosion damage will weaken the material property, which serve as crack nucleation sites. Proper hardening constituent element introduced during alloying process such as Si, Mg, who are in proper ratio of component to form strengthening phase Mg2Si without the excess phase of single crystal Si, will make strength and plasticity match, thus improve fatigue performance of materials.

Abstract: In this paper, the graphene-polyaniline (PANI) nanocomposite thin film was prepared by the in situ self-assembly method for the ammonia (NH3) gas sensor application, which was characterized by scanning electron microscopy (SEM) and UV-vis spectroscopy. The NH3 sensing performance and mechanism of the nanocomposite film were investigated. The results revealed that the sensor based on graphene-polyaniline nanocomposite film exhibited better sensing properties and restorability than those of single graphene film.

Abstract: In this paper, we proposed a measure method of the passive rubidium frequency standard system in residual field bubble chamber volume. A new method is employed. We assess the impact of size on the amount of remaining field frequency stability by changing the ambient temperature.

Abstract: A novel flocculus-like CuO microstructure exhibiting excellent electrochemical hydrogen capacity of 210 mAh/g were fabricated using Cu (OH)₂ as precursor. By altering the initial concentration of NaOH, novel butter-like and flower-like CuO microstructures without electrochemical hydrogen capacity were also obtained. Field emission scanning microscopy (FESEM) and X-ray power diffraction (XRD) were characterized the as-obtained products. The dosage of NaOH plays a vital role in controlling the morphology, which affects electrochemical hydrogen capacity of final products.

Abstract: A novel pH sensitive cadmium sulfide quantum dot (CdS QD) was prepared by a coprecipitation method in the presence of pH sensitive poly (2-(dimethylamino) ethyl methacrylate)-co-poly (2-(dibutylamino) ethyl methacrylate)(PDMA-PDBA) copolymer. CdCl₂ and Na₂S were mixed in aqueous media in the presence of PDMA-PDBA. The amine groups of PDMA were anchored on the surface of the formed CdS nanoparticles, whereas the PDBA segment was anchored on the surface to form a hydrophilic palisade at low pH environment, thus turn on the fluorescence CdS QD probe; at high pH value, PDBA segments precipitate and turn off fluorescence because of the phase separation. This novel pH sensitive fluorescene CdS QDs probe have great application potential for target imaging of cancer.

Abstract: The different mixing ratios of TiO₂ nanoparticles were synthesized using sol–gel process by changing the temperature of calcinations. The crystal structures were characterized by X-ray diffraction (XRD). The photocatalytic action of TiO₂ nanoparticles was investigated through the photooxidation of Rhodamine B in aqueous solution. The XRD results indicated that the rutile ratios of different calcination temperatures (500°C, 600°C, 700°C and 800°C, respectively) TiO₂ nanoparticles were 0%, 20.87%, 92.41% and 100%, respectively. The TiO₂ nanoparticles which calcinated at 600 °C had the highest photocatalytic action; under UV irradiation of 4 h, initial Rhodamine B concentration of 15 mg/L, TiO₂ nanoparticles (calcinated at 600 °C) dosage of 1g/L, the degradation rate of Rhodamine B could achieve to 97.87%. The addition of rutile to anatase could particularly improve the photooxidation activity of TiO₂ nanoparticles.