Advanced Materials Research Vols. 1120-1121

Abstract: The La_0.8Sr_xCa_0.2-xMnO₃ (x=0, 0.05 and 0.15) compounds were synthesized by combining sol-gel method and high temperature sintering. The effects of Sr doping content on the microstructure, metal-insulator transition and magnetoresistance (MR) of the La_0.8Sr_xCa_0.2-xMnO₃ were investigated. The results show that the La_0.8Sr_xCa_0.2-xMnO₃ exhibit single perovskite phase and the change of Sr doping content can result in phase structure transition. The La_0.8Sr_0.15Ca_0.05MnO₃ is rhombohedra structure and the La_0.8Sr_xCa_0.2-xMnO₃ shows distorted cubic structure when x is no more than 0.05. Increasing Sr doping content causes the degeneration of microstructure homogeneity and density and the decrease of average grain size of the La_0.8Sr_xCa_0.2-xMnO₃, which can be attributed to the weakening of atomic diffusion during the sintering process. The metal-insulator transition temperature (T_MI) of the compounds increases with the decrease of Sr doping content due to the improvement of microstructure. The La_0.8Sr_0.15Ca_0.05MnO₃ has the highest MR peak value, which is about 95%. The La_0.8Ca_0.2MnO₃ has the highest room temperature MR, which is about 28%. Moreover, the magnetoresistance of the La_0.8Ca_0.2MnO₃ is very stable between 125~300K.

Abstract: The wettability of Sn-0.3Ag-0.7Cu-xPr solders on Cu substrate was determined by the wetting balance method， and the mechanical properties of Sn-0.3Ag-0.7Cu-xPr joints were investigated. The result showed that the wetting force of Sn-0.3Ag-0.7Cu-xPr is increased and the wetting time is decreased with the Pr content addition. Good wettability of Sn-Ag-Cu-Pr is obtained with around 0·05%-0·1% (mass fraction) Pr. When measured at 260°C， the wetting force of of SnAgCu solder was increased by 5.0% with 0.1%Pr and the wetting time of SnAgCu solder was descreased by 16.9%.The mechanical properties of soldered joints are enhanced with the addition of Pr， and the soldered joints possess the peak values of shear stress when the Pr addition is about 0.05% in Sn-Ag-Cu-Pr solder joint.

Abstract: This paper provides a new lead-free alloys with Sn, Ni, P and Mg. The liquidus of Sn-Ni alloys, Sn-P alloys, and Sn-Mg alloys was tested. And each of element affection was analyzed. The wettablity of Sn-Ni alloys ,Sn-P alloys, and Sn-Mg alloys was tested. And each of element affection was analyzed. In addition, the comparison of the liquidus and wettablity of different alloys was gave.

Abstract: In this study the effects of small amounts of nickel addition (0-2000 ppm) on the microstructure, on Cu6Sn5 intermetallic compound formation and the mechanical properties of a Sn-0.5Cu lead-free solder were investigated. It is known that even ppm level additions of Ni have significant effects on the microstructure of Sn-Cu solder alloys. Ni suppresses the growth of β-Sn dendrites in favour of eutectic formation. As the nickel content increases, the microstructure undergoes a morphology evolution from hypoeutectic through fully eutectic to hypereutectic. Furthermore, the presence of Ni in the Cu6Sn5 intermetallic compound phase stabilises its high-temperature allotrope η-Cu6Sn5.

Abstract: In order to investigate the effect of annealing temperature on oxygen clusters’ evolution in silicon wafer during low temperature annealing, a phase-field model and it’s algorithm were established, and the changes of the oxygen clusters’ structure, amount (concentration) and sizes were simulated at different annealing temperature. The results show that when the temperature varies from 923 to 1023K, the oxygen clusters with reasonable amount and average size can be gained; when the temperature is too higher or lower, the suitable oxygen clusters cannot be found; it is verified that the established model and its algorithm have credible thermodynamics and experimental basis.

Abstract: A kind of nonwoven containing ferulic acid is prepared by electrospinning method. It was observed that the diameter of the fiber was about 200 nm by SEM. The antibacterial activities against Escherichia coli and S. aureus were also investigated. The result showed the nonwoven prepared was effective against Escherichia coli, and S. aureus. Furthermore, Fabric UV transmittance test and air permeability were taken. It was found that the nonwoven achieved good UV protection and air permeability.

Abstract: In this paper, the radome materials suitable for mid-infrared /millimeter wave multimode were introduced, as well as the properties. In comparison with the difference of the radome materials, the polycrystalline magnesium fluoride was promising for the radome of mid-infrared /millimeter wave multimode. Furthermore, the millimeter wave transparent properties of polycrystalline magnesium fluoride were studied by the simulation based on moment method and multilevel fast multipole method.

Abstract: Thermoelectric materials are of interest for applications as heat pumps and power generators. Thermoelectric properties of Sn_xGa_1−xN alloys have been investigated. It was found that as Sn concentration increases, the thermal conductivity decreases and power factor increases, which leads to an increase in the TE figure of ZT. The valuge of ZT was found to be 0.07 at 300 K for Sn_0.38Ga_0.64N alloy. The results indicate that SnGaN alloys could be potentially important TE materials for many applications, especially for prolonged TE device operation at high temperatures, such as for recovery of waste heat from automobile, aircrafts, and power plants due to their superior physical properties, including the ability of operating at high temperature/high power conditions, high mechanical strength and stability, and radiation hardness.

Abstract: Using Orange Peels as Raw Material, a Stacking Structured Carbon Material has been Synthesized through Carbonizing and Activating Process. an Orange Peel Carbon/sulfur (OPC/S) Composite as a Cathode for Rechargeable Lithium/sulfur (Li/S) Batteries is Designed by Loading Sulfur into the Orange Peel Carbon (OPC) via Simple Impregnation and Heat Treatments. the OPC/S Composite Exhibits a High Discharge Capacity of 1100 mAh g⁻¹ at 0.1 C, which is 23% Higher than that of Pristine Sulfur. Moreover, OPC/S Shows much Better Rate Capability and Excellent Cyclability. this Enhanced Electrochemical Performance could Be Attributed to the Thin Sheets and Irregular Wrinkled Surface of the OPC, which Act as a Conductor to Provide a Highly Conductivity and Short Li⁺ Diffusion Distance, as well as Absorbs Polysulfides.

Abstract: In order to develop a new way for utilizing Polyacrylonitril (PAN) fiber wastes, a super-absorbent resin was prepared using the waste of PAN fibers at alkaline hydrolysis condition with Al³⁺ as cross-linker. The molecular structure of the super-absorbent resin was confirmed by FTIR. The thermal degradation of super-absorbent resin consisted of one main weight loss step. Factors that can influence absorbencies of the super-absorbent resin were investigated, such as the amount of cross-linker. The super-absorbent resin has the water absorbency of 131g/g in distilled water. The super-absorbent resin can be used as a new material to water retention from the soil in agriculture.