Surface plasmon enhanced GaAs thin film solar cells

As a new method to improve the light trapping in solar cells, surface plasmon resonance (SPR) has attracted considerable attention because of its unique characteristics. Several studies have been reported on the photocurrent improvement of Si solar cells by surface plasmons, while little research has been done on III-V solar cells. In this work, we performed a systematic study of SPR on GaAs thin film solar cells with different sizes of Ag nanoparticles on the surface. The nanoparticles were fabricated by annealing E-beam evaporated Ag films in a N₂ atmosphere. It was found that the surface plasmon resonance wavelength does not undergo a simple red-shift with increasing metal thickness. It depends on the shape of the metal nanoparticles and the interparticle spacing. It is necessary to optimize the particle size to obtain an optimum enhancement throughout the visible spectrum for solar cells. We found that the optimum thickness of the Ag film was 6 nm under our experimental conditions. Furthermore, from the calculation based on the external quantum efficiency data, the short circuit current density of a GaAs solar cell with 6 nm Ag film after annealing was increased by 14.2% over that of the untreated solar cell.     

IrFeOx/SiO2—A highly active catalyst for preferential CO oxidation in H2

A novel bifunctional catalyst IrFeO_x/SiO₂, which was very active and selective for preferential oxidation of CO under H₂-rich atmosphere, was developed in this study. XRD, H₂-TPR, and chemisorption were applied to characterize three kinds of IrFeO_x/SiO₂ catalysts prepared by different impregnation sequences. The results indicated that both FeO_x and Ir species were highly dispersed on the SiO₂ support; the reduction of Ir species in the Fe-promoted Ir/SiO₂ catalyst became easier than those in the Ir/SiO₂, together with the partial reduction of Fe₂O₃; the saturation uptake of O₂ adsorption was greatly enhanced. In-situ DRIFTS, XPS, and Mössbauer techniques were further applied to detect the structural information on the selected Ir-FeO_x/SiO₂ catalyst prepared by co-impregnation method. A non-competitive adsorption catalytic mechanism was proposed where CO adsorbed on Ir sites and O₂ adsorbed on FeO_x sites; the reaction probably took place at the interface of Ir and FeO_x or via a spill-over process.     

联合法制钛小型试验中镁利用率与还原主控条件的线性回归

根据镁法炼钛还原过程的理论与实践,选取镁利用率(M%)与还原期三个主控参数(四氯化钛加料速度W、还原反应温度T及反应器内压强p)的影响关系为模型,对联合法制钛小型试验中的试验数据,用数理方法进行了线性相关和回归分析,建立了近似反映镁利用率与还原参数的数学模型.     

Electromechanical stability of semi-crystalline polymer

Semi-crystalline polymers are widely used in manufacturing drivers and capacitors. The two opposite surfaces of semi-crystalline polymer are coated with flexible electrodes and are applied with voltage. Because of static electricity field, semi-crystalline polymer film thins down along the thickness direction while extends along the horizontal direction. Reduction of thickness will lead to a higher electric field, and the positive feedback system has been sustained. When the electric field reaches the critical breakdown of electric field of semi-crystalline polymers, electromechanical coupling system of semi-crystalline polymers becomes unstable. Based on the method on electromechanical instability of semi-crystalline polymers under non-linear field, we use exponential model with two material constants to analyze the electromechanical stability of semi-crystalline polymers. Then, we obtain the relationship among the true critical stress, the true critical electric field of different semi-crystalline polymers and stretching rate. The numerical results show that, when the material ratio C (K₂ = CK₁,K₁ and K₂ are the parameters determined by the experimental stress-strain relationship) of the two material constants increases, the true critical electric field and electromechanical stability of semi-crystalline polymers will decrease. In addition, when C = 0, our result coincides with previous results. It is proved that pre-stretching load can increase the critical breakdown voltage of the polymer. Our conclusions may provide the guidance in designing material and manufacturing semi-crystalline polymer.     

蛭石在膨胀阻燃聚乙烯中的协效作用

研究了蛭石对膨胀阻燃聚乙烯体系的协效作用。氧指数和力学性能测试结果表明:阻燃剂用量超过15份时,蛭石协同膨胀阻燃聚乙烯体系的氧指数超过23.4%,离火后很快自熄,而添加相同量阻燃剂聚乙烯的氧指数仅为21.3%;添加适量改性蛭石可以提高膨胀阻燃聚乙烯体系的拉伸强度,而聚乙烯的缺口冲击强度在添加阻燃剂后,均有不同程度的下降。