Advanced Materials Research Vol. 716

Abstract: In this paper, CdTe thin films were deposited on soda-lime glass substrates using CdTe powder as a source by close-spaced sublimation at higher source temperature of 700°C. The influence of the deposition time and the source-substrate distance on the chemical composition, crystal phase, surface morphology and optical band gap of CdTe thin films was systemically investigated by energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscope and the ultraviolet-visible-near infrared absorption spectra, respectively. At the deposition time of 60 min and the source-substrate distance of 5 mm, the CdTe thin films had pyramid appearance with the grain size of 15 μm.

Abstract: Cu₂ZnSnS₄ (CZTS) thin film was successfully prepared by pulsed laser deposition using CZTS nanocrystal as a source and the thin film solar cell with the novel structure of FTO/CdS/CZTS/Mo was assembled. At the laser incident energy of 6 J·cm^-2, the chemical composition of the CZTS thin film was Cu_1.74Zn_0.80Sn_1.00S_4.04, near to stoichiometric ratio. The thin film solar cell with the novel structure of FTO/CdS/CZTS/Mo gave short circuit photocurrent density of 1.01 mA·cm^-2, open circuit voltage of 0.39 V, and fill factor of 0.485, corresponding to the photoelectric conversion efficiency of 0.19% at the illumination (Air Mass 1.5, 100 mW·cm^-2).

Abstract: Room-temperature photoluminescence (PL) properties of the Tb³⁺ ion implanted non-stoichiometric silicon nitride (SiN_x:Tb³⁺) and silicon dioxide (SiO_x:Tb³⁺) were studied. The films were deposited by plasma-enhanced chemical vapor deposition (PECVD) and then annealed at different temperatures for 1 hour in flowing N₂ after the Tb ion-implantation. Results show that there are four intense PL peaks due to the intra-4f transitions of Tb³⁺ in the wavelength from 470 nm to 625 nm for both kinds of films. Moreover, the PL intensity of Tb³⁺:SiN_x is much higher than that of Tb³⁺:SiO_x. The less oxygen content of the SiN_x film and, more importantly, the faster recombination lifetime of Tb³⁺ ion in SiN_x film are the main reasons. This result shows that SiN_x:Tb³⁺ can be used for silicon-based light emission materials.

Abstract: Linear polyvinyl alcohol ( PVA ) as the matrix, Glutaraldehyde as crosslinking agent, the crosslinked polyvinyl alcohol microspheres ( CPVA ) was prepared by inverse microemulsion polymerization. Influence factors for forms and particle size of crosslinking spheres such as the ratio of oil and water, reaction temperature and time, crosslinking agent and catalyst use level, stirring speed. When reaction conditions changed, the particle size would change accordingly.

Abstract: Flame resistance is an important item for filter medium on some baghouse application with fire accident easy to occur. In order to choose the filter correctly to reduce the occurence of fire, based on the vertical flame method and the limit oxygen index method, some flame expriments are done for domestic polyphenylene sulfide filter, polyester fliter, Polyimide filter, PTFE fliter, foreign and domestic Polyphenylene sulfide and PTFE blended filter, foreign polyphenylene sulfide processed by PTFE latex ,domestic and foreign polyphenylene sulfide each accounted for 50% processed by PTFE.The results show that the flame resistance of Polyester filter is bad, and don't conform to the flame retardant standard. PTFE is good. The flame resistance of filter can be improved by filter blended with PTFE or post-processing of dipping with PTFE liquid.

Abstract: Using Thermo-calc software, transformation points as well as bainite starting temperature of the CP steel studied in the present work were calculated. Based on the measured CCT curve, the steels were treated at different conditions using Gleeble-3500 thermal simulation tester. To study the effects of cooling conditions on mechanical properties and microstructure of the steels after austenization, a combination of tensile tests at room temperature, SEM and TEM techniques was applied. Results showed that effective design of chemical composition and heat treatments can be achieved using Thermo-Calc software. The CP steel with carbon equivalent of 0.43% achieved B/M complex microstructure when austenized at 975 °C and followed by isothermal holding at bainitic transformation temperature of 450 °C. The tensile strength is 843.29 MPa and the elongation is 14.28%.

Abstract: Primary loop recirculation (PLR) piping weld joints in light water reactor (LWR) environments are more susceptible to stress corrosion cracking (SCC). Limited experimental work also suggested the complicated material and mechanical property of the fusion zone and the heat affected zone (HAZ) especially in dissimilar weld joints might play an important role in promoting SCC growth. In our study, different from the former sandwich like weld joint, a model of continuous heterogeneity mechanical property was established, the effect of welded mechanical heterogeneity on the stress-strain field and J-integral along the crack fronts at different locations were simulated in an Alloy 182-A533B dissimilar weld joint by the elastic-plastic finite element method (EPFEM). The results indicate that the crack near the dividing line of base metal (BM) and HAZ has higher resistance to SCC. At the dividing line of HAZ and weld metal (WM), the crack is prone to propagate into the WM, and will present more complex crack morphology and behaviors.

Abstract: Several type of gold precursors including pre-synthesized Au (en)₂Cl₃ and gold colloid were tried to intercalate into the layer space of Na-Montmorillonite (Na-MMT). In the preparation, DDA and PAA were employed to cap the pre-synthesized gold colloidal particles and then intercalated into Na-MMT, and the Au (en)₂Cl₃ was directly intercalated to Na-MMT through cation exchange. X-ray diffraction (XRD), fluorescence analysis (XRF) and transmission electron microscopy (TEM) were used to characterize the prepared samples. The results showed that the gold colloid modified by dodecylamine (DDA) and polyallylamine hydrochloride (PAA) respectively were successfully intercalated into the layer gallery of Na-MMT based on the mechanism of covalent capture. However, thermal treatment at 773K for 2h resulted in migration of gold nanoparticles from layer space to the out surface of the Na-MMT.

Abstract: La_0.6Sr_0.4MnO₃ and hollow glass microspheres with different weight ratio have been prepared by sol-gel method. The structure, morphology and microwave absorption properties have been investigated. The results shown that the ratio of La_0.6Sr_0.4MnO₃ to hollow glass microspheres has great influence on reflection loss. The optimal absorption property can be obtained when the ratio is 6:1, which is attributed to the proper magnetic loss of La_0.6Sr_0.4MnO₃ coating layers.

Abstract: Polyaniline (PANI)/zinc oxide (ZnO) nanocomposites have been synthesized by in-situ polymerization of aniline monomer with ZnO nanomaterials. The PANI/ZnO nanocomposites were used as photocatalyst in the photodegradation of methylene blue dye (MB) molecules in aqueous solution. The results showed that PANI/ZnO nanocomposite greatly enhanced photocatalytic activities compared with pristine polyaniline might due to high photoexcited electronhole pairs charge separation. The photocatalytic activities of PANI/ZnO nanocomposites increased with increasing ZnO content, however, further increasing ZnO content over 50% induced the formation of more agglomerates, which could act as recombination centers of photoexcited electronhole pairs, leading to decreased photocatalytic activity. The kinetics of photodegradation of MB dye using PANI/ZnO(ZnO content 50 % ) nanocomposites photocatalyst was found to be of the first order.