应力对La_(0.8)Ca_(0.2)MnO_3薄膜电输运性能的调控研究

采用脉冲激光沉积技术,在LaAlO3和0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3两种单晶基片上外延生长了La0.8Ca0.2MnO3薄膜.X射线衍射分析表明两种薄膜皆为单取向生长,且面内分别受到压应力和张应力作用.晶格失配造成的应力对薄膜的电阻和金属-绝缘相转变温度Tp影响很大.对LCMO/PMN-PT施加外电场,从而调节薄膜所受应力也可以调制其电阻和Tp.     

Study of phase separation in Ga25Se75 xTex chalcogenide thin films

The effects of composition and thermal annealing in between glass transition and crystallization temperature on the optical and structural properties of Ga25Se75-xTex were investigated. The glass transition and crystallization temperature of the synthesized samples was measured by non-isothermal DSC measurements. Amorphous thin films of Ga25Se75-xTex glasses were grown onto ultra clean glass/Si wafer (100) substrates using the vacuum evaporation technique. The effect of thermal annealing on the optical gap (Eg) for Ga25Se75-xTex thin films in the temperature range 358-388K is studied. As-prepared and annealed thin films were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and optical absorption. Thermal annealing was found to be accompanied by structural effects, which in turn, lead to changes in the optical constants. The optical absorption coefficient (a) for as-deposited and thermally annealed films was calculated from the absorbance data. From the knowledge of absorption coefficient at different wavelengths, the optical band gap (Eg) was calculated for all compositions of Ga25Se75-xTex thin films before and after thermal annealing. Results indicate that allowed indirect optical transition is predominated in as-deposited and thermally annealed thin films. The influence of Te incorporation and thermal annealing in Ga25Se75-xTex thin films results in a gradual decrease in the indirect optical gap, this behaviorcan be explained as increased tailing. The decrease in optical band gap and an increase in absorption coefficient and extinction coefficient with thermal annealing can be attributed to transformation from amorphous to crystalline phase.     

Influence of catalyst on structural and morphological properties of TiO2 nanostructured films prepared by sol–gel on glass

Transparent TiO2 thin films have been prepared by the sol-gel method using titanium alkoxides as precursors.Thin films were deposited on glass supports by the dip-coating technique.The TiO2 layer acts as a self-cleaning coating generated from its photocatalysis and photoinduced superhydrophilicity.The crystalline structure of TiO2 films was dominantly identified as the anatase phase,consisted of uniform spherical particles of about 14-50 nm in size,which strongly depends upon catalyst-type and heat treatment temperature.Increasing heat treating temperature can lead to an increase in crystalline size.The results indicated that the sample S.S(sample derived from sol containing sulfuric acid as catalyst) exhibits superhydrophilic nature and better photocatalytic activity,which can be attributed to its higher anatase content and lower crystalline size.Morphological studies,carried out using Atomic Force Microscopy(AFM),confirm the presence of crystalline phase with such a grain size and low surface roughness.Thus,the applied films exhibiting high photocatalytic activity,superhydrophilic behavior,and low surface roughness can be used as an efficient self-cleaning coating on glass and other optical applications.     

4He和12C离子Rutherford背散射的Geant4模拟

利用Geant4程序模拟270,500 keV  ⁴He和¹²C离子垂直入射Au,Ag,Cu薄膜上的Rutherford背散射谱（RBS）, 并讨论材料、 厚度和入射离子能量对背散射谱的影响. 结果表明, 能量较大的¹²C离子具有较好的质量分辨率.     

Effects of HNO3 concentration on the pit morphologies of aluminum foil etched in HNO3–HCl and HNO3–H2SO4–HCl solutions

In this work, the effects of HNO₃ concentration on the pit morphologies of high-cubic-texture aluminum foil etched in HNO₃–HCl and HNO₃–H₂SO₄–HCl solutions were investigated. When the aluminum foil was etched in HNO₃–HCl solutions, the morphologies of pits transformed from irregular tunnels to typical tunnels (as inverted pyramids) and shallow cuboids as the HNO₃ concentration in the etchant solution was increased. However, as the HCl concentration in the etchant solution was increased, the morphologies of pits transformed from shallow cuboids to typical tunnels (as inverted pyramids) and irregular tunnels. When the aluminum foil was etched in n N HNO₃–(7.2?n) N H₂SO₄–0.8 N HCl solutions, the morphologies of the pits transformed from typical tunnels (i.e., the number of sub-tunnels formed on the main tunnels increased) to irregular tunnels (corrugated tunnels and polyline tunnels) as the HNO₃ concentration in the etchant solution was increased. These effects are attributed primarily to corrosion on the (100) and (010) faces of pits being accelerated and to the (001) faces being prone to passivation to different degrees when various concentrations of HNO₃ are added to the etchant solutions.     

磁控溅射法制备铝掺杂氧化锌薄膜研究进展

铝掺杂氧化锌(AZO)薄膜是一种n型半导体光学透明薄膜,具有优异的光电转换特性.综述了磁控溅射法制备AZO薄膜的研究现状.介绍了衬底温度、溅射功率、氧分压、溅射角度、衬底类型和退火温度等工艺参数对AZO薄膜的微结构、表面形貌和光电性能的影响.展望了其今后的研究方向和应用前景.     

TiO_2薄膜光催化性能研究进展

TiO2能有效催化降解空气和水中的有机和无机污染物,又不产生二次污染并可重复使用,在废水处理、空气净化、杀菌除臭等领域有巨大的应用前景.该文论述了纳米TiO2薄膜的光催化原理、添加剂以及制备工艺等方面的研究现状,列举了TiO2薄膜研究中尚待解决的一些问题,并对其进行了展望.     

Ag-聚酯复合薄膜的微结构与光学性能研究

用匀胶机在载玻片上甩制5%的硅酸乙酯薄膜,在该薄膜上用磁控溅射法溅射Ag制备半连续的纳米微粒Ag薄膜,经过不同温度下的退火,处于膜表面的Ag颗粒的扩散运动增强,从而得以渗入高分子聚酯层形成Ag-聚酯复合薄膜.采用X射线衍射和紫外-可见光谱等检测手段对其微结构和光学性能进行测试与分析发现:随着退火温度的增加,Ag晶粒的晶化现象越来越明显,平均晶粒尺寸和晶格常数均呈增大趋势.随着Ag质量分数的增加,Ag的XRD衍射峰出现并逐渐增强,Ag纳米颗粒表面等离子体共振吸收峰位置逐渐红移并逐渐增强.     

真空喷射射流流场的Fluent模拟分析

为了对真空射流流场进行研究,应用Fluent软件并基于VOF(volume of fluid)方法、k-ε标准湍模型及PISO算法,对不同喷口直径及入射压力的直射式锥型流道喷嘴的射流流场速度和湍流运动分布进行了数值模拟分析.结果表明:1)入口压力相同,喷嘴直径越大,射流与周围介质间的速度梯度越大,可促进射流的扩散和液滴破碎后的尺寸均匀分布;2)喷嘴直径一定,入口压力在10~15 MPa内,射流湍流强度分布达到最佳状态,射流流场较好;3)如果不考虑材料的溶解性,相对于三氯甲烷和四氯化碳,丙酮作为溶剂时的液体喷射雾化效果较好,适于制备质量较好的高分子薄膜.     

等厚干涉法测量薄膜厚度的两种方法

等厚干涉法测量薄膜厚度设备简易,操作方便,分析直观,在生产中有着广泛的应用.本文探讨了两种等厚干涉法测量薄膜厚度的原理与方法,利用预先形成的薄膜台阶产生空气或透明材料劈尖,单色光在劈尖上下两界面的反射光发生相干叠加产生干涉条纹,通过条纹相关参数的测量,获得薄膜的厚度.通过比较,空气劈尖法较之薄膜劈尖法操作更简易、准确,因而更实用.