Preparation and Microstructure of Highly-Oriented LaNiO_3 Thin Films by RF Sputtering Method

In an attempt of being used as buffer layers and electrodes for the textured BaTiO3 (BTO) ferroelectric thin films, highly (100)-oriented LaNiO3 (LNO) thin films of different thicknesses were deposited directly on Si (100) substrate with radio-frequency (RF) magnetron sputtering method. It is observed that the substrate temperatures and the film thicknesses bring main influences on the micro-structures and orientation of the thin film. The effects of the thicknesses and substrate temperatures on the orientation of the films were studied on the LNO films of different thicknesses. The highly (100)-oriented LNO thin films were obtained at the substrate temperature of 600 ℃. The existence of epitaxially grown BTO films indicates that the oriented LNO thin films obtained in this work could be used as a buffer layer for epitaxial growth.     

在高职高专基础上构建应用型本科会计专业实践教学体系的探索

如何做好从高职高专教育到应用型本科教育的衔接,是大多数刚刚“升本”的高校所要面临的重要课题.从会计专业实践教学来看,这一课题就是要在高职高专教育实践教学的不足基础之上,建立适合应用型本科的会计专业实践教学体系.     

2006年桂林市民媒体接触状况的调查与分析

通过对桂林市民的媒体接触状况的调查,了解桂林市的电视、广播、报纸、网络等媒体的现状和受众的媒介接触习惯,把握受众需求,为桂林市各媒体制定其发展战略提供依据。     

试析语音系属不同的湘南土话的词汇特点

目前学界根据语音特点,将永州岚角山土话归为湘语色彩较浓的土话,把桂阳流峰土话归为赣语特色较浓的土话。本文试着举例性地分析了两种土话的词汇特点后认为,这两种土话都有突出的混合方言的性质,岚角山更接近湘语,又混有其他方言特点;流峰有些偏向湘语,又有明显的赣语成分。     

《元曲选》的用韵和《中原音韵》研究

文章对《元曲选》四千多支曲子进行了穷尽式的考察研究，井与《中原音韵》进行了对比研究。厘析井分析了各部相押的情况，力图探究其本源，了解元代口语的实际面貌。文章还对《中原音韵》和《元曲选》相互未出现的字进行了对比考察。最后得出结论：《元曲选》所体现的韵部，大致能代表元代口语的基本特征，与《中原音韵》的归纳也是一致的；同时，也认为周德清井未详细地归纳元人的创作。     

先驱体转化法制备SiC/Si_3N_4复相陶瓷异型件──烧成工艺研究

研究了以先驱体为粘合剂制备SiC／Si3N4复相陶瓷异型件的烧成工艺，以及升温制度等对制品质量的影响。     

Effect of Water Absorption on the Impact Properties of Carbon Fiber/Epoxy Composites

In this paper, the effects of test temperatures and time on the impact damage behavior of unidirectional carbon fiber reinforced epoxy resin composites, immersed in pure water, on a pendulum impact tester, was studied. The results show that immersion in liquids has a significant effect on the impact resistance of the unidirectional composite material. It is obvious that after immersion, the mass of the material increases. The fracture initiation forces as well as the fracture initiation energy decrease as the immersion time lengthens. Moreover, the higher the temperature and the longer the time are, the more the crack propagation energy and the ductility index will be. Immersion makes the fracture mode change from the dominant fiber fracture into dominant delamination. All in all, immersion decreases the impact resistance of the composites and causes the fracture mode to change.     

Preparation and Properties of Organically Modified Sepiolite/High-performance Epoxy Nanocomposites

Fibrous organic sepiolites (OSEP) and novel epoxy/OSEP nanocomposites were prepared, and different methods were investigated to produce an intercalated/exfoliated structure of OSEP. Experimental results show that the modifier molecules can be easily adsorbed by the sepiolite, but the layer space (d001) of the sepiolite, linked by means of covalent bond, remains unchanged. A proper method to solve this problem appears to exert large shearing force on the original sepiolite followed by its organic modification (OSEP2). The morphol-ogy observation shows that there are formed an even dispersion of nano-sized OSEP2 fibers in epoxy resin and a structure intercalated by epoxy molecules, which lead to significantly improved mechanical properties. Impact strength of the epoxy/OSEP2 nanocomposite increases from 32.1 kJ/m2 to 44.4 kJ/m2, 38.3% higher than that of pristine matrix with 3 wt% OSEP2 content. It is also noted that the flexural strength of the OSEP/epoxy composites has risen by about 3% higher than that of the pure epoxy resin.     

Mechanical Properties and Microstructure of In Situ TiB_2-7055 Composites

In order to fabricate a kind of high strength particulate reinforced aluminum-matrix composites, the high strength aluminum alloy 7055 was selected as a matrix. Composites reinforced with varying amounts of TiB2 particles were synthesized using the in situ method, and their mechanical properties and microstructure were analyzed. It is found that the in situ TiB2 particles sized from 50 to 400 nm uniformly disperse in the matrix. With the weight fraction of TiB2 particles increasing, the elastic modulus as well as the yield strength and the ultimate tensile strength increase, while the ductility decrease. The improvement of strength could be attributed to good bonding between TiB2 and the matrix, and also the TiB2 particles act as a barrier to dislocation.     

Change of Electronic Structure and Magnetic Properties with MgO and Fe Thicknesses in Fe/MgO/Fe Magnetic Tunnel Junction

The effects of the thickness of MgO and Fe on the electronic structure and magnetic properties of Fe/MgO/Fe magnetic tunnel junction was studied using the first principle method. Two series of models with MgO of different thicknesses: Fe(3)MgO(t)Fe(3) (t=1,3,5,7) and with Fe of varied thicknesses: Fe(t)MgO(3)Fe(t) (t=3,4,5,6,7) were established. Calculated results show that in all the models the magnetic moment of Fe increases at the Fe/MgO interface and surface as compared with that of the inner layers. The mag-netic moment of each Fe layer was found to be independent of MgO thicknesses, while the spin-polarization of Fe layer at the interface shows a slight change in function of the MgO thicknesses. The tunneling magnetoresistance (TMR) ratio estimated by the Julliere model has the same change tendency as the spin-polarization has, and the largest value is obtained at the MgO thickness of 5 atomic layers. When the Fe thickness increases, the spin-polarization of interface Fe layer follows up an increase with a decrease. The highest TMR value is achieved when the Fe thickness is of 4 atomic layers.