Ag纳米粒子磁控溅射制备及其热稳定性研究

利用磁控溅射在玻璃衬底上制备Ag纳米粒子及其氧化物（AgOx）薄膜，通过高温退火实验，研究银及AgOx薄膜的热稳定特性。采用x射线衍射分析薄膜的晶相结构，采用UV-Vis分光光度计测定薄膜的吸收光谱。结果表明：Ag纳米薄膜在450nm附近出现特征吸收峰，200℃退火后，峰位蓝移，400℃退火后，吸收峰显著减弱，表明Ag纳米粒子在退火过程中发生了蒸发；AgOx薄膜在200℃下退火后，出现Ag纳米粒子特征吸收峰，表明AgOx的热分解，400℃退火同样导致Ag纳米粒子的蒸发。     

SiNx薄膜中硅纳米粒子的制备及表征

通过等离子增强化学气相沉积(PECVD)法, 以氨气和硅烷为反应气体, P型单晶硅和石英为衬底, 低温下(200℃)制备了含硅纳米粒子的非化学计量比氮化硅(SiN_x)薄膜. 经高温(范围500~950℃)退火处理优化了薄膜结构. 室温下测试了不同温度退火后含硅纳米粒子SiN_x薄膜的拉曼(Raman)光谱、光致发光(PL)光谱及傅立叶变换红外吸收(FTIR)光谱, 对薄膜材料的结构特性、发光特性及其键合特性进行了分析. Raman光谱表明. SiN_x薄膜内的硅纳米粒子为非晶结构. PL光谱显示两条与硅纳米粒子相关的光谱带, 随退火温度的升高此两光谱带峰位移动方向相同. 当退火温度低于800℃时, PL光谱峰位随退火温度的升高而蓝移. 当退火温度高于800℃时, PL光谱峰位随退火温度的升高而红移. 通过SiNx薄膜的三种光谱分析发现薄膜的光致发光源于硅纳米粒子的量子限制效应. 这些结果对硅纳米粒子制备工艺优化和硅纳米粒子光电器件的应用有重要意义.     

纳米硅基薄膜光致发光机制的初步研究

用等离子体化学气相沉积方法制备氢化非晶硅合金薄膜，经高温退火及高温氧化可制备纳米尺寸的晶粒，室温下能发出可见光。实验表明，高温氧化后的纳米颗粒被镶嵌在ＳｉＯ２的无序网络中，其晶粒尺寸减少，而发光强度增强，发光峰位置向短波方向移动。这些结果说明，发光来源于纳米晶粒的量子尺寸效应和覆盖晶粒表面的ＳｉＯ２层的发光中心。     

金纳米粒子的最新研究进展

金纳米粒子是最稳定的金属纳米粒子之一，由于其具有优良的稳定性和光学性质，使其在许多领域有着广阔的应用前景。本文主要对金纳米粒子和表面修饰金纳米粒子的制备方法进行分析总结，指出各种方法的制备原理及特点。同时，阐述了金纳米粒子的一些特殊性能，如：表面吸收带效应、荧光效应、量子尺寸效应、单电子跃迁等。并对金纳米粒子的应用进行了展望。     

纳米颗粒复合硅橡胶电子显微分析与性能研究

水热法制备的纳米钌在空气中600℃退火30min获得粒径小于20nm金红石结构的导电二氧化钌。为了提高导电粒子在硅橡胶中的均匀分布，用乙烯基硅烷偶联剂对氧化钌表面进行改性，将改性的二氧化钌与硅橡胶复合制得导电硅橡胶。利用透射电子显微镜对颗粒的分布做了形象的分析。复合材料的低温电导测量表明，材料玻璃化转变显著地改变了宏观电导行为。     

《自然》：首次从分子层次证明纳米催化的形貌效应

4月9日，《自然》杂志发表了中科院大连化物所纳米催化研究的最新成果。该文章揭示了纳米催化中的形貌效应，通过对金属氧化物纳米粒子尺寸和形貌的调控，首次实现了金属氧化物催化一氧化碳低温氧化的高活性和高稳定性。申文杰研究员团队与中国科学院金属所刘志权研究员、日本首都大学（东京）春田正毅教授合作，利用形貌控制概念使得制备的Co304纳米棒表面暴露41％的活性（110）晶面。     

真空高温热退火对单晶磷化铟纳米孔阵列的形貌、微结构影响

利用真空热退火的方法，研究了单晶InP方形纳米孔阵列退火后的形貌和晶相等特征。发现随着退火温度的不断升高，单晶InP中P的挥发性也越来越剧烈，到650℃后P完全挥发，样品变成h单质，而单晶InP方形纳米孔阵列的形貌也逐渐变得不均一，当退火温度高于550℃，整个纳米孔阵列被完全破坏。     

预掺杂法制备Au/TiO2纳米管薄膜及其光电性能研究

提出了一种在TiO_2纳米管(TNT)阵列形成之前将贵金属纳米粒子作为掺杂剂引入的预掺杂法,该方法可以有效地避免传统掺杂方法中贵金属粒子堵塞纳米管管口的问题。首先采用磁控溅射法在FTO导电玻璃基底上制备Au/Ti双层金属薄膜,然后将上层金属Ti膜进行电化学阳极氧化,退火后即可获得Au/TNT电极薄膜。利用扫描电子显微镜、X射线衍射和X射线光电子能谱分别对Au/TNT电极薄膜的微观结构和组成成分进行了观察和表征,确定Au元素存在于复合薄膜中的同时,还发现位于薄膜底部的Au纳米颗粒,经阳极氧化和退火后,扩散到了上层的TNT阵列薄膜中。测试发现,可见光照射下,Au/TNT电极薄膜的光电流密度和光催化降解率分别约为纯TNT阵列薄膜的2.0和1.3倍。因此,采用预掺杂法制备光电性能优良的Au/TNT电极薄膜是可行有效的。     

退火对Al2O3/SiC纳米复合材料裂纹愈合行为的影响

研究不同密度的Al2O3/SiC纳米复合材料在退火条件下的裂纹愈合行为。利用维氏压痕法引入可控的预制裂纹，通过测量退火前后材料抗弯强度的变化来表生裂纹愈合程度。当退火温度在850℃以上时，裂纹愈合效应随退火温度提高明显增强，在1150℃左右退火1h后，不同密度的试样的抗弯强度均恢复到试样的固有强度。裂纹愈合的机制主要归结于退火过程中残余应力的驰豫导致扩散键合和裂纹表面碳化硅颗粒的氧化作用。然而，过度的氧化会降低裂纹愈合的效果。     

四氧化三铁载银纳米粒子的原位制备及其抗菌应用

采用高温裂解法制备四氧化三铁纳米粒子,并在其表面上通过还原乙酸银原位生长银纳米晶,制备特异形貌、均匀分散的四氧化三铁载银(Fe_3O_4@Ag)纳米粒子。利用透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、X射线衍射仪(XRD)、振动样品磁强计(VSM)、紫外-可见分光光度计(UV-Vis)等表征技术对Fe_3O_4@Ag纳米粒子的结构和性能进行表征。通过分别研究实验制备的纳米颗粒对葡萄球菌和大肠杆菌的抗菌能力,分析Fe_3O_4@Ag纳米粒子的抗菌性能。结果表明,Fe_3O_4@Ag纳米粒子不仅具备四氧化三铁的室温超顺磁性,同时对葡萄球菌和大肠杆菌表现出优良的抗菌性能。利用如此方法构筑的多功能纳米材料——Fe_3O_4@Ag纳米粒子,将来在靶向抗菌、生物分离等领域具有重要的应用前景。     

Impurity doping effect on photostriction in PLZT ceramics

Photostriction is the superposition of a photovoltaic and piezoelectric effects. In this study, photostrictive effects in the perovskite (Pb, La) (Zr, Ti)O₃ were investigated as a function of B-site impurity doping. Donor doping was found to reduce both the grain size and room-temperature dielectric constant, influencing photovoltaic response. WO₃ and Ta₂O₅ doping increase the photovoltaic response, but do not significantly affect the piezoelectric effect in this material. Maximum photostriction is obtained for samples with 0.4 at% WO₃ doped or 1 at% Ta₂O₅ doped PLZT     

Temperature effects on (1+1)-dimensional steady-state bright spatial solitons in biased photorefractive crystals with both the linear and quadratic effects

Abstract

The temperature effects on the intensity profile, self-deflection process, and stability of (1 + 1)-dimensional steady-state bright solitons resulting from both the linear and quadratic electro-optic effects are comprehensively analyzed. Moreover, three physical factors, i.e. diffusion effect, dark irradiance, and the dielectric constant, have been investigated through the theoretical analysis to determine which one dominates the temperature dependence of intensity profile and self-deflection of bright solitons. It is also found that the incident beam evolves into stable bright solitons in the vicinity of initial temperature, but oscillates or even collapses when the crystal temperature deviates significantly from the initial temperature.     

自旋Seebeck效应实验研究进展

自旋Seebeck效应是自旋热电子学(Spin caloritronics)领域中反映自旋流和热流之间相互作用关系的重要物理现象。它具有重要的科学研究价值和深远的应用前景,得到了国内外相关研究组织的广泛关注。通过对自旋Seebeck效应的研究意义进行简单介绍,重点分析了由热流激发自旋波(自旋流)引起的自旋Seebeck效应的物理机制,并对其探测方法以及现阶段存在的问题进行了着重阐述。     

碳纤维水泥基复合材料的阻-温特性

研究了碳纤维水泥基复合材料的阻-温特性。发现当温度低于某一特定值时，电阻率随温度的升高而单调降低(NTC效应)。超过此值时，则表现为电阻率随温度升高而大幅度单调增加(PTC效应)。普通水泥基材料不具有相应的阻-温特性．     

Self-focusing effects in an organic photorefractive film without a biased field

We report the observation of self-focusing effects in organic photorefractive films based on a carbazole derivative and sensitizer 2,4,7-trinitro-9-fluorenone at 632.8 nm wavelength without applying a biased field, owing to the orientationally enhanced photorefractive nonlinearity caused by photopolymerization of the carbazole derivative. The experiment was repeated in three samples with different sensitizer doping percentages and similar phenomena were observed.     

Surface effect aero-hydrodynamics and its applications

Surface effect aero-hydrodynamics, as one of the influencing factors in the design and operation of wing-in-ground effect vehicles, is briefly illustrated. Some important issues are discussed. These include high lift/drag configuration, power augmented ram, flight stability and control and wind-wave effects on aerodynamics.     

乳胶渗透蒸发膜分离醇水混合物

以苯乙烯、丙烯酸丁酯为单体进行乳液聚合,将聚合获得的乳胶直接浇铸制备出乳胶膜．将该膜用于水－乙醇混合物的渗透蒸发分离,优先透水,渗透通量为50一450g／（m2·h）,分离因子为80～260．考察了乳胶膜的选择性及料液浓度对乳胶膜分离性能的影响．研究了塑化效应和耦合效应对组分渗透的影响,发现在乳胶膜中,乙醇的存在有利于水的渗透,而水的存在会阻止乙醇的渗透．     

波形齿锚具锚固CFRP片材的力学性能试验研究及锚具体系设计

针对波形齿锚具受力机理中的粘结、摩擦及弯曲效应设计出多种锚具,用碳纤维布制作若干多层布CFRP片材的小试件并用这几种锚具进行拉伸试验,从而实现锚固长度计算公式中参数进行试验研究并对其进行量化。同时还进行了有粘结型与无粘结型波形齿锚具锚固CFRP片材的试验,结果表明:波形齿锚具是以第一排螺杆轴力增量为主来增大摩擦力实现可靠锚固CFRP片材。并提出设计螺杆时其轴力与剪力值可取CFRP片材极限抗拉强度的百分率。     

Mutual Insight on Ferroelectrics and Hybrid Halide Perovskites: A Platform for Future Multifunctional Energy Conversion

An insight into the analogies, state‐of‐the‐art technologies, concepts, and prospects under the umbrella of perovskite materials (both inorganic–organic hybrid halide perovskites and ferroelectric perovskites) for future multifunctional energy conversion and storage devices is provided. Often, these are considered entirely different branches of research; however, considering them simultaneously and holistically can provide several new opportunities. Recent advancements have highlighted the potential of hybrid perovskites for high‐efficiency solar cells. The intrinsic polar properties of these materials, including the potential for ferroelectricity, provide additional possibilities for simultaneously exploiting several energy conversion mechanisms such as the piezoelectric, pyroelectric, and thermoelectric effect and electrical energy storage. The presence of these phenomena can support the performance of perovskite solar cells. The energy conversion using these effects (piezo‐, pyro‐, and thermoelectric effect) can also be enhanced by a change in the light intensity. Thus, there lies a range of possibilities for tuning the structural, electronic, optical, and magnetic properties of perovskites to simultaneously harvest energy using more than one mechanism to realize an improved efficiency. This requires a basic understanding of concepts, mechanisms, corresponding material properties, and the underlying physics involved with these effects.     

Influence of interface states and deep levels on output characteristics of InAlAs/InGaAs/InP HEMTs

The aim of this work is to study the origin of parasitic effects observed on the output characteristics of InAlAs/InGaAs/InP HEMTs with various buffer layers. I_ds − V_ds measurements as a function of the temperature have first been performed. Several anomalies were observed such as kink and hysteresis effects. C-DLTS measurements have also been performed. From the obtained results, we have established a strong correlation between parasitic effects observed on the output characteristics and deep levels located near the buffer layer interface.