制备透射电子显微镜金属薄膜样品的自动控制装置

一、前 言 Heidenreich[1]于1949年首先用3 × 0.12毫米的铝片做成薄膜,并用透射电子显微镜进行了观察.由于当时对电子衍衬成象认识不清,用透射电镜研究金属薄膜的工作停顿了一段时期,直到五十年代后期才蓬勃开展.当时大多采用窗法制备金属薄膜,为了解决样品在电解抛光减薄时面积迅速缩小的问题,在样品四周涂一层清漆进行绝缘,或采用一对尖阴极,使样品表面的电流密度分布有利于中心的减薄.这种方法需要面积较大的样品(1-2厘米2),抛光后割下的薄膜也要用两片铜网夹持才能进行观察[2].为了克服这些缺点,Strutt[3]用一束电解抛光液喷射到样品…     

热处理温度对量子点玻璃介电函数的影响

为了明确热处理温度对熔融法制备Pb Se量子点玻璃光电特性中介电函数的影响,实验上在不同核化时间、晶化温度条件下制备了多种样品。通过对样品透射电子显微镜的观测,确认样品在不同条件下都有一定量的晶体形成。由于晶化程度、晶体大小及浓度有所不同,导致其吸收光谱有一定差异。利用各个样品的吸收光谱,结合米氏散射理论和克拉默斯-克勒尼希关系,通过多次迭代运算,从吸收光谱中分离出相应的介电函数的实部和虚部,最终获得材料的吸收系数和折射率。分析表明退火温度对量子点玻璃的吸收系数和折射率分布有明显的影响,为了获得具有优良光电性能的量子点材料,退火时间和退火温度的合适选择至关重要。     

PC/YAG：Ce荧光树脂的制备及光谱分析

采用熔融共混法和高温压模法制备出PC/YAG:Ce荧光树脂片,样品经减薄和抛光处理后,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、光致发光(PL)、透射光谱等测试手段进行分析。厚度为0.87 mm的样品在500~800 nm范围内的透过率约为65%。样品主相为Y₃Al₅O₁₂,在342 nm和448 nm有两个激发峰。样品的发射光谱在532 nm有一宽峰,属于Ce³⁺的5d→4f特征跃迁发射。荧光树脂片中荧光粉含量越高,样品发射强度越大,是一种适合用于白光LED封装的新型荧光材料。     

扫描隧道电子显微镜──1986年获诺贝尔物理奖项目之一

透射电子显微镜(TEM)在观察物质的整体结构方面是很有用的,但在表面结构的分析上却较困难.这是因为透射电子显微镜是由高能电子透过样品来获得信息的,一反映的是样品物质的内部信息.扫描电子显微镜(SEM)虽然能揭示一定的表面情况,但由于入射电子总具有一定能量,会穿入样品内部,因此分析的所谓“表面”’总在一定深度上[1].而且分辨率也受到很大限制.场发射电子显微镜(FEM)和场离子显微镜(FIM )虽然能很好地用于表面研究,但是样品必须特殊制备,只能置于很细的针尖上[2]并且样品还需能承受高强电场.这样就使它的应用范围受到了限制。 扫…     

常温常压下BiMnO_3纳米粉末的制备与物性分析

钙钛矿型BiMnO3是同时具有铁磁性和铁电性的多铁性材料,在传感器,信息存储等方面具有潜在的应用前景.但是它的制备条件非常苛刻,需要高温、高压、密封等,这极大地限制了它的应用与发展.本文采用共沉淀法,以MnCl2·4H2O,Bi2O3,NaOH,HNO3和聚乙二醇为材料,在100℃的水溶液中成功地制备出了BiMnO3材料,此方法大大降低了制备的温度和压强,从而节约了能源,降低了成本.同时利用X射线衍射仪(XRD),透射电子显微镜(TEM),振动样品磁强计(VSM)等对其结构、相貌及磁性等进行了检测,并讨论了制备条件及煅烧温度对BiMnO3物性的影响.     

LiFePO4纳米管的制备与表征

采用溶胶凝胶法在氧化铝模板中成功的制备了LiFePO4一维纳米管阵列．扫描电子显微镜和透射电子显微镜表征结果表明所制备的LiFePO4纳米管具有单分散性,互相平行,高度有序。综合选区电子衍射、X射线衍射以及X光线能谱表征结果,所制备的LiFePO4纳米管为单一的橄榄石型结构．这种在室温和温和条件下合成的一维LiFePO4纳米管,可以做为新型的锂离子电池正极材料．     

铁镍合金纳米管阵列的模板制备和磁性

"在阳极氧化铝模板的孔洞中利用模板浸润的方法成功制备出了铁镍合金纳米管阵列．通过改变所用模板的参数和沉积纳米管的的制备条件,所制备的纳米管的长度、内径和外径的尺寸都可以得到有效控制．利用扫描电子显微镜和透射电子显微镜对所制备的纳米管及其阵列的形貌进行了表征．对铁镍合金纳米管阵列的宏观磁性测量表明样品具有磁各向异性,沿纳米管长轴方向样品更容易被磁化．对纳米管的磁化反转机制和磁矩在纳米管中的静态分布进行了讨论．铁镍合金纳米管的这些性质都是由纳米管的独特结构造成的．"     

电化学抛光对Ni-5%W基底的影响

超导涂层导体是解决当今能源危机的一个重要材料,而Ni合金基带是制备高性能涂层导体的基础.本论文将高温固溶后的Ni-5%W基带在磷系抛光液中进行电化学抛光,通过对抛光电流密度和抛光时间的探索,认为0.1~0.12A/cm~2,2~2.5min条件下能够获得非常平整的基带表面,样品的均方根粗糙度RMS=0.889nm.并通过自氧化外延NiO阻隔层进一步验证了抛光的可行性和必要性.为后续涂层的制备打下良好的基础,对制备高性能超导涂层导体具有重要指导意义.     

离子轰击减薄装置及其应用

对材料作显微观察分析时,需要对材料表面腐蚀或将材料减簿.因为腐蚀之后所显示的腐蚀图象,在一定程度上反应材料的组织和结构.在用透射电子显微镜观察材料内部组织和结构时,需要将材料减薄,制成数千埃至数万埃厚度的薄样品.近年来常用离子轰击方法腐蚀或减薄样品,离子轰击减薄方法能减薄其它方法难以减薄的材料,如多相材料、硬的脆的材料、烧结多孔材料,以及橡胶、高分子、生物等.离子轰击方法也可用于制备电子显微镜复型、投影[1]和高分辨电子显微术[2]. 我们参考了霍耶尔(Heuer)等人的工作[3],制作了一台冷阴极辉光放电型离子轰击装置,进…     

高硬度超导三元碳化物的高温高压合成

采用高温高压合成手段,以纯度均在99.8%以上的钼粉、钨粉和石墨粉作为合成原料,在压强5.0GPa、温度2 000K、保温时间60min的条件下成功制备出MoWC_2样品。利用X射线衍射仪、扫描电子显微镜、透射电子显微镜、显微硬度仪、综合物性测量系统和热重-差热分析仪对合成样品进行了物性表征。结果表明:合成的MoWC_2晶体为六角结构,其空间群为P6-m2;晶粒大小为1~4μm,结晶质量良好;MoWC_2的收敛硬度值为15.3GPa;氧化温度为450℃;温度低于6.8K时体现超导电性。MoWC_2的轨道杂化很强,因而具有较高的硬度和抗氧化性。同时,MoWC_2费米面处态密度和德拜温度较高,使其成为一种超导材料。由此可知,MoWC_2是一种兼具超导性、耐热性和较高硬度的硬质超导多功能材料。     

Dependence of the atomic structure and surface relief of platinum foils on the annealing and rolling conditions

The effect of cold rolling, polishing, and thermal annealing conditions on the atomic structure and surface geometry of platinum foils has been studied. The surface morphology has been analyzed using low-energy electron diffraction, atomic force microscopy, and scanning tunneling microscopy. The chemical composition of the surface has been evaluated by Auger electron spectroscopy. It has been demonstrated that a variation in the conditions used for the preparation of the samples makes it possible to produce surfaces with different degrees of perfection from atomically smooth to rippled, fractal, and diffraction-disordered surfaces.     

Chemical polishing method of GaAs specimens for transmission electron microscopy

A practical method for transmission electron microscopy specimen preparation of GaAs-based materials with quantum dot structures is presented to show that high-quality image observations in high-resolution transmission electron microscopy (HRTEM) can be effectively obtained. Specimens were prepared in plan-view and cross-section using ion milling, followed by two-steps chemical fine polishing with an ammonia solution (NH₄OH) and a dilute H₂SO₄ solution. Measurements of electron energy loss spectroscopy (EELS) and atomic force microscopy (AFM) proved that clean and flat specimens can be obtained without chemical residues. HRTEM images show that the amorphous regions of carbon and GaAs can be significantly reduced to enhance the contrast of lattice images of GaAs-based quantum structure.     

Influence of TEM specimen preparation on chemical composition of Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals

The influences of different transmission electron microscopy (TEM) specimen preparation techniques on the chemical composition of Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PMN–PT) single crystals was studied. Ion-milled samples where no cooling with liquid nitrogen (L-N₂) was applied show permanently changed composition also deep inside the bulk material. When the PMN–PT samples were cooled to L-N₂ temperature during the ion-milling process and in addition lower accelerating voltages were used, the chemical composition was altered only in the thinnest parts close to the specimen edge. Samples prepared using only tripod polishing technique show compositional irregularities close to the specimen edge. For the preparation of lead-containing samples, such as PMN–PT single crystals, a combination of tripod polishing and short Ar-ion-milling at low accelerating voltages while cooling the samples to liquid nitrogen temperature proved to be the most suitable to obtain artefact-free electron-transparent TEM lamellae.     

The morphology of submicronsized core-shell latex particles: an electron microscopy study

The core-shell structure of a range of acrylic-acrylic latexes has been investigated by combining different specimen preparation methods with transmission electron microscopy (TEM), dark-field scanning transmission electron microscopy (DSTEM) and low-voltage scanning electron microscopy (LV-SEM), including the first reported use of LV-SEM to observe composite latex particles at ambient and subambient temperatures. Spin-coating of liquid latex dispersions directly onto TEM grids or SEM stubs is shown to be a relatively straightforward mean of avoiding film formation during specimen preparation. In conjunction with double staining techniques, it has been found to be particularly convenient for characterizing the fine structure of particles with diameters down to below 100 nm.     

Preparation of metallized GaN/sapphire cross sections for TEM analysis using wedge polishing

The tripod polisher has been used successfully in the past, in the preparation of difficult Si-based TEM cross-section specimens. Good TEM specimens, with large electron transparent areas, can be prepared in a relatively short time. In addition, wedge polishing considerably reduces the ion milling time because of the thinness of the final specimen. For metallized GaN on sapphire substrates, there are problems not inherent to Si-based materials: (1) sapphire is a difficult material to thin due to its high hardness and its mechanical instability when thinned below 20 m; (2) delamination of metal layers from the GaN can occur during polishing and/or ion milling; (3) markedly different ion milling rates for the metals and semiconductors. In this paper, wedge polishing has been modified to make it suitable for preparation of metallized GaN/sapphire samples or other metallized semiconductors and ceramics for TEM analysis. Using this method, TEM cross section specimens can be prepared with reasonably large thin areas.     

提拉生长铌酸锶钠锂晶体的组分过冷及提高晶体品质的研究

本文采用厚晶体抛光、腐蚀、显微观察的方法研究提拉法生长晶体的组分过冷。在高温偏光下研究了铌酸锶钠锂晶体的结构转变温度。采用最佳的生长和工艺条件克服了铌酸锶钠锂晶体的组分过冷和内部生长条纹,提高了晶体的光学均匀性。 关键词：     

Planarization machining of sapphire wafers with boron carbide and colloidal silica as abrasives

The as-cutted sapphire wafers are planarized by the grinding and polishing two-step machining processes with micrometer B₄C and nanometer silica as abrasives, respectively. The material removal rates (MRRs) of two processes are measured. During the polishing process, the MRR increases with the down-pressure increased, whereas the rotational speeds have less effect on the MRR. The alkaline colloidal silica is more favorable than the acidic to polish sapphire wafer. The ground and polished surfaces of the substrate are compared by scanning electron microscopy, atomic force microscopy, and X-ray rocking curves. Our results show that B₄C abrasives are effective in elimination of the ununiformity in thickness within a wafer. The colloidal silica can achieve a nanoscale flatness of wafer, but the lasting polishing time seems unfavorable. The polishing process is also analyzed in terms of chemical mechanical polishing mechanism.     

On the oxidation of CaF2 in transmission electron microscope

Electron stimulated oxidation of CaF₂ in transmission electron microscope has been thoroughly studied using various electron microscopy techniques, including imaging, electron diffraction and electron energy-loss spectroscopy. It found that the electron irradiation induced CaO locate on the edge of specimen. The oxidation process is associated with desorption of F by electron irradiation, and originates from O impurities in the specimen. Driven by electric field produced by electron irradiation, the O ions inside bulk diffuse to the edge region, occupying the interstitials of metallized Ca lattice. Therefore, the accumulation of O along the edge of specimen results in forming CaO.     

Carbide precipitates in solution-quenched PH13-8 Mo stainless steel: A small-angle neutron scattering investigation

This paper deals with the small-angle neutron scattering (SANS) investigation on solution-quenched PH13-8 Mo stainless steel. From the nature of the variation of the functionality of the profiles for varying specimen thickness and also from the transmission electron microscopy (TEM), it has been established that the small-angle scattering signal predominantly originates from the block-like metallic carbide precipitates in the specimen. The contribution due to double Bragg reflection is not significant in the present case. The single scattering profile has been extracted from the experimental profiles corresponding to different values of specimen thickness. In order to avoid complexity and non-uniqueness of the multi-parameter minimization for randomly oriented polydisperse block-like precipitate model, the data have been analyzed assuming randomly oriented polydisperse cylindrical particle model with a locked aspect ratio.     

基于散粒磨料振动抛光非球面加工技术研究

鉴于非球面光学元件的应用日益广泛,非球面加工技术成为研究热点,提出一种基于散粒磨料振动抛光非球面的加工方法。非球面元件待抛光表面与磨粒均匀接触,通过振动抛光装置为游离磨粒提供抛光作用力,使材料去除均匀,降低表面粗糙度。以材料为ZK-10L、尺寸为Φ55 mm的光学元件为实验对象,分析了振动幅度、抛光液浓度、磨粒粒径和抛光时间对抛光效果的影响,当振动幅度为5 mm、抛光液浓度为80 g/L、磨粒粒径为1 mm时,振动抛光8 h后试件的表面粗糙度从84.4 nm降低到9.4 nm,而试件的面形精度基本不变,从而在保证面形的前提下达到抛光的目的。