Highly active lanthanum doped nickel anode for solid oxide fuel cells directly fuelled with methane

Lanthanum doped nickel and YSZ composite anode (LaNi–YSZ) exhibited a greatly reduced polarization resistance and high performance for electrochemical oxidation of hydrogen and methane, which resulted from a fine anode structure with a high dispersion of nickel catalyst and a high catalytic activity towards methane.     

B2O3/TiO2-ZrO2催化剂上环己酮肟的气相Beckmann重排反应

用共沉淀法制备了TiO2-ZrO2复合氧化物载体，BET，DTA，XRD表征结果表明，该复合载体具有较大的比表面和较好的热稳定性，对于环己酮肟气相Beckmann重排反应制己内酰胺，用复合载体制备的B2O3／TiO2-ZrO2催化剂，比分别以TiO2,ZrO2为载体所制备的B2O3/TiO2和B2O3／ZrO2催化剂具有更高的活性和选择性，实验表明，催化剂表面中等强度的酸位是环己酮肟气相Beckmann重排反应的有效活性中心。     

中国软磁铁氧体用氧化铁

介绍了中国软磁铁氧体用氧化铁的发展历史和现状，预测了未来的市场需求，并探讨了氧化铁的应用技术问题。     

Oxidation behavior of silicide coating on Ti3SiC2-based ceramic

A silicide coating was prepared on Ti₃SiC₂-based ceramic by pack cementation to improve the oxidation resistance of Ti₃SiC₂, which is a technologically important material for high temperature applications. The microstructure, phase composition and oxidation resistance of the coated sample were investigated. The results demonstrated that the silicide coating was mainly composed of TiSi₂ and SiC. A single layer of a mixture of SiO₂ and TiO₂ was formed on the surface of the coated sample during isothermal oxidation at 1100 °C and 1200 °C for 20h. Compared to Ti₃SiC₂, the parabolic rate constant of silicide coated Ti₃SiC₂ decreased by 2~3 orders of magnitude. Furthermore, the coated sample showed much better cyclic oxidation resistance than Ti₃SiC₂ during the cyclic oxidation at 1100 °C for 400 times. However, during the preparation of the coating, a number of fine cracks formed in the outer layer of the coating. When these cracks penetrated the whole coating during the cyclic oxidation, the oxidation rate was accelerated, which degraded the oxidation resistance. Electronic Publication     

Comparative hall measurements on wet- and dry-oxidized 4H-SiC MOSFETs

Hall measurements have been used to compare the properties of 4H-SiC inversion-mode MOSFETs with “wet” and “dry” gate oxides. While the field-effect mobilities were approximately 3–5 cm²/Vs, the Hall mobilities in 4H-SiC MOSFETs in the wet and dry oxide samples were approximately 70–80 cm²/Vs. The dry-oxidized metal oxide semiconductor field effect transistors (MOSFETs) had a higher transconductance, improved threshold voltage, improved subthreshold slope, and a higher inversion carrier concentration compared to the wet-oxidized MOSFETs. The difference in characteristics between the wet- and the dry-oxidized MOSFETs is attributed to the larger fixed oxide charge in the dry oxide sample and a higher interface trap density in the wet oxide sample.     

Influence of heat transfer on anodic oxidation of aluminium

The influence of convective heat transfer on constant current density anodizing of aluminium in sulfuric acid has been examined in a wall-jet electrode reactor. The uniformity of the anodic film thickness is related to the local electrode temperature distribution, which is dependent on the convection. The higher the local temperature, the greater the local oxide thickness. An increased local temperature enhances local field assisted oxide dissolution at the pore bases, and consequently acts to increase the local current density. At relatively high current densities, local features develop on the electrode surface, accompanied by high initial, local temperature rises. The relevance of such local features, limiting useful oxide growth, is considered further.     

Origin of visible photoluminescence from porous silicon as studied by Raman spectroscopy

In this paper we discuss the different models proposed to explain the visible luminescence in porous silicon (PS). We review our recent photoluminescence and Raman studies on PS as a function of different preparation conditions and isochronal thermal annealing. Our results can be explained by a hybrid model which incorporates both nanostructures for quantum confinement and silicon complexes (such as SiH _x and siloxene) and defects at Si/SiO₂ interfaces as luminescent centres.     

氢化非晶硅磷掺杂工艺条件的研究

本文对氧化非晶硅磷掺杂的工艺条件进行了研究，得出掺磷氢化非晶硅的电导率随衬底温度、气体流量、气体压力、射频功率、淀积时间的变化关系，为非晶硅的有效掺杂和器件研究提供了依据。     

Microstructure-related fracture toughness and fatigue crack growth behaviour in toughened, anhydride-cured epoxy resins

Fracture toughness and fatigue crack propagation (FCP) of plain and modified anhydride-cured epoxy resin (EP) were studied at ambient temperature. Liquid carboxyl-terminated acrylonitrile-butadiene (CTBN) and silicon (SI) rubber dispersions were used as tougheners for the EP. The morphology of the modified EP was characterized by dynamic mechanical analysis (DMA) and by scanning electron microscopy (SEM). The fracture toughness, K_c, of the compositions decreased with increasing deformation rate. K_c of the EP was slightly improved by CTBN addition and practically unaffected by incorporation of the SI dispersion when tests were performed at low cross-head speed, v. Both modifiers improved K_c at high v, and also the resistance to FCP, by shifting the curves to higher stress intensity factor ranges, ΔK, by comparison with the plain EP. It was established that both fracture and fatigue performance rely on the compliance, J_R, at the rubbery plateau, and thus on the apparent molecular mass between crosslinks, M_c. The failure mechanisms were less dependent upon the loading mode (fracture, fatigue), but differed basically for the various modifiers. Rubber-induced cavitation and shear yielding of the EP were dominant for CTBN, whereas crack bifurcation and branching controlled the cracking in SI-modified EP. The simultaneous use of both modifiers resulted in a synergistic effect for both the fracture toughness at high deformation rate and the FCP behavior.     

Sol-gel processing: A versatile concept for special glasses and ceramics

The various parameters related to sol-gel processing are discussed with special reference to those which usually attract less attention but depending on the final product in mind, can play important roles. The versatility of the sol-gel technique in materials preparation is demonstrated by discussing the various products developed at the author’s laboratory by using this processing method.