Sc2－xGaxW3O12体系负热膨胀性能研究

通过固相反应法,在1100 ℃下成功制备出了系列Ga掺杂Sc_2-xGa_xW₃O₁₂（x=0, 0.05, 0.1, 0.2, 0.3, 0.5, 0.8）固溶体.X射线粉末衍射结构精修表明,Ga以替代Sc的形式成功进入Sc_2-xGa_xW₃O₁₂晶格,但不能获得端元组分Ga₂W₃关键词： 负热膨胀 热膨胀系数 Rietveld结构精修     

嵌入原子法计算金属钚中点缺陷的能量

钚因放射性衰变而出现老化效应.钚中点缺陷的性质和行为是理解钚老化效应的一个基础和前提.运用分子动力学模拟技术,计算了金属钚中点缺陷和点缺陷团簇的形成能和结合能.其中钚-钚、钚-氦和氦-氦相互作用势分别采用嵌入原子多体势、Morse对势和Lennard-Jones对势.计算结果表明,单个自间隙原子易以〈100〉哑铃状形态存在;间隙氦原子在理想晶格的八面体间隙位置相对较为稳定;氦原子与空位的结合能较大,在钚的自辐照过程中两者易于结合并形成氦-空位团簇;氦-空位团簇的形成能随氦原子数的增加而增大,当氦与空位的数     

电沉积Cu-In-Ga金属预制层的硒硫化研究

以H₂S气体作为硫源、固态蒸发硒蒸气作为硒源对电沉积Cu-In-Ga金属预制层进行硒硫化处理. 通过电沉积Cu-In-Ga金属预制层在不同衬底温度下硒化、硫化和硒硫化的对比实验,发现CuInS₂相和CuIn（S,Se）₂相优先生成,抑制了CuInSe₂相的生成,促使InSe相薄膜向内部扩散,减弱了薄膜两相分离现象. 采用先硒化后硒硫化处理工艺优化了Cu（In,Ga）（S,Se）₂薄膜的制备工艺,在250 ℃预硒化得到了开路电压为570 mV的太阳电池,在更高的预硒化温度得到了较大短路电流的太阳电池,最终优化得到了效率达到10.4%的电池器件. 关键词： 电化学沉积 Cu-In-Ga金属预制层 硒硫化处理 2薄膜')" href="#">Cu(In,Ga)(S,Se)₂薄膜     

Photoelectrochemical property and photocatalytic activity of N-doped TiO2 nanotube arrays

N-doped TiO₂ nanotube arrays (NTN) were prepared by anodization and dip-calcination method. Hydrazine hydrate was used as nitrogen source. The surface morphology of samples was characterized by SEM. It showed that the mean size of inner diameter was 65 nm and wall thickness was 15 nm for NTN. The ordered TiO₂ nanotube arrays on Ti substrate can sustain the impact of doping process and post-heat treatment. The atomic ratio of N/Ti was 8/25, which was calculated by EDX. Photoelectrochemical property of NTN was examined by anodic photocurrent response. Results indicated the photocurrent of NTN was nearly twice as that of non-doped TiO₂ nanotube arrays (TN). Photocatalytic activity of NTN was investigated by degrading dye X-3B under visible light. As a result, 99% of X-3B was decomposed by NTN in 105 min, while that of TN was 59%.     

A time domain correction method for Doppler-distortion signal from acoustic moving source

Doppler effect widely exists in the signal from the moving acoustic source. In order to solve such problems as frequency shift and frequency band expansion, a time domain cor- rection method is presented in this paper. First, the discrete time vector for interpolation and the amplitude restoration formula is derived based on the moving relationship and the Morse acoustic theory, then the amplitude weights are corrected and the distortion signal is interpolated. Every point of the discrete signal is operated separately in time domain. Compared with the existing frequency domain methods, this method does not need to know the characteristic frequency beforehand and would not be influenced by the blending of the frequency band. Hence, this method can be employed to correct multiple frequency signals and it is also a simple and effective Doppler effect reduction method.     

AA bilayer graphene on Si-terminated SiO2 under electric field

The AA-stacked bilayer graphene/α-SiO2 （001） interfaces with Si terminated atoms are studied in the presence of an electric field F with different intensities by first principles. AA-stacked bilayer graphene is slightly mis-oriented on SiO2 substrate without electric field and the band gap is 0.557 eV. However, as F increases, the AA-stacked bilayer graphene has its layers gradually vertically shifted with each other and, finally, transfers into AB-stacked bilayer graphene and the band gap reduces to 0.252 eV under 0.015 Hartree.     

Synthesis of fluorine-doped titania-coated activated carbon under low temperature with high photocatalytic activity under visible light

Fluorine-doped anatase titania sols were synthesized by hydrolysis of titanium-n-butoxide in the presence of abundant acidic aqueous solution and using ammonium fluoride as fluorine precursors, under mild condition. The prepared fluorine-doped titania nanoparticles were loaded on activated carbon in a rotatory evaporator under vacuum to form a composite photocatalyst. X-ray diffraction, Fourier transform infrared spectrum analysis, UV-visible spectroscopy, scanning electron microscope and Brunauer-Emmett-Teller adsorption measurement were used to characterize these as-prepared powders. The photocatalytic activity of the sample was evaluated by degrading phenol under visible light. Results showed that the composite photocatalyst was porous due to its nano-microstructure. The number of hydroxyl groups on the titania surface was enhanced after fluorine doping. Compared with pure titania-activated carbon and Degussa P25, the as-prepared composite powders exhibited much higher photocatalytic activity, although absorption response range into the visible region was not detected by diffuse reflection spectra.     

磁控溅射法制备极紫外6.8～11.0nm波段Mo/B_4C横向梯度多层膜（英文）

用直流磁控溅射法结合掩模板控制膜厚的方法在Si衬底上制备了工作于6.8～11.0nm波段的[Mo/B_4C]60横向梯度多层膜。利用X射线掠入射反射测试以及同步辐射反射率测试对梯度多层膜的结构及性能进行了测试。X射线掠入射反射测试结果表明,多层膜周期厚度沿着长轴方向从4.39nm逐渐增加到7.82nm,周期厚度平均梯度为0.054nm/mm。对横向梯度多层膜沿长轴方向每隔5mm进行了一次同步辐射反射率测试,结果显示,横向梯度多层膜在45°入射角下的反射率约为10%,反射峰的半高全宽介于0.13nm到0.31nm之间。     

Direct observation of the saturation of stimulated Brillouin scattering by ion-trapping-induced frequency shifts

We report the first measurement of the saturation of stimulated Brillouin scattering (SBS) by an ion-trapping-induced frequency shift, which was achieved by directly measuring the amplitude and absolute frequency of SBS-driven ion-acoustic waves (IAW). A frequency shift of up to 30% and a simultaneous saturation of driven IAW and SBS reflectivity were observed. The scaling of the frequency shift with the IAW amplitude compares well with theoretical calculations. We have further measured fast 30 ps oscillations of the SBS-driven IAW amplitude induced by the frequency shift.     

氧化钒-碳纳米管复合薄膜的制备及特性

提出了一种制备氧化钒热敏电阻薄膜的新方法。采用紫外光和过氧化氢相结合的方法,对多壁碳纳米管进行功能化处理,然后通过溶胶-凝胶法,使功能化碳纳米管与V2O5相复合,制备氧化钒-碳纳米管复合薄膜。与单纯的氧化钒薄膜相比,氧化钒-碳纳米管复合膜的薄膜方阻和光学带隙发生减小,而电阻温度系数(TCR)和光吸收率相应增大。复合膜还具有更高的载流子迁移速率,更加适合应用到红外探测器当中。