Name: characterization of ultra-fine grained and nanocrystalline materials using transmission kikuchi diffraction
Uploaded: 2017-04-01T15:00:00.000+00:00
Duration: 9 min 13 s
Description: Watch this Scientific Journal Video about Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction at JoVE.com

The authors acknowledge the facilities, and the scientific and technical assistance, of the Australian Microscopy &amp; Microanalysis Research Facility at the Australian Centre for Microscopy and Microanalysis, The University of Sydney. This research was partially supported by funding from the Faculty of Engineering &amp; Information Technologies, The University of Sydney, under the Faculty Research Cluster Program, from the Regional Council of Champagne-Ardenne (France) through the NANOTRIBO project and from the European FEDER program.

1.设备和样品要求<ol><li>使用配备了电子背散射衍射检测器的SEM来进行实验。 注意:理想情况下，SEM应该有一个场发射源，以最大限度地提高空间分辨率，但该技术可以在任何类型的SEM的工作。 </li><li>确保待分析的样品具有以获得最佳效果17的厚度在100纳米的范围内。验证样本足够薄，以便能够进行TKD分析。 注意:这可以使用forescatter探测器来完成，试样越薄，越暗它将被使用的成像技术。 <ol><li>准备使用TEM箔样品制备的传统技术的样品，例如通过使用一个凹坑粉碎机，然后或者电解或离子研磨，或通过使用使用聚焦离子束（FIB）的顶出技术如果待分析的特征是位点特异性。 注:制备技术不EXPLained在这里详细地，因为它们不是本文的目的，并且是相同的TEM样品制备22的良好建立的技术。用户将需要确定合适的样品制备技术是对自己的标本。信息可以在22找到。 </li></ol></li></ol> 2.实验装置<ol><li>放置在试样保持器，其允许样品是在从水平20°，一旦SEM室内部的样品。这将允许样品被挂在一旦放置在水平当前位置由20°倾斜的阶段之后的圆盘传送带（参见步骤2.4），以避免数据采集与EBSD照相机期间遮蔽效应。 注:特殊试样保持器已经被设计用于该目的，一个示例在图1中示出。如果样品是FIB电梯出来TEM网格样品，确保样品是在下表面ÒF中的支撑格栅。 </li></ol><img alt="图1" src="/files/ftp_upload/55506/55506fig1.jpg" /> 图1. TKD试样保持器。一些标本可以在一个会话中，而不需要重新打开SEM室进行分析。重要的是在TEM箔被定位，没有保持器或支持防止电子从样品被衍射，并通过EBSD照相机来收集这样的方式。不要使用网格将与收集到的信号产生干扰。 <a href="http://ecsource.jove.com/files/ftp_upload/55506/55506fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <ol start="2"><li>在SEM室地方样本保持器，关闭该室，并通过点击在真空标签泵启动抽真空作为用于任何其他样品。 </li><li>使用在室等离子清洁，以防止污染。 注意:这一步是可选的，但强烈推荐ED，以提高数据质量和可靠性。如果该技术是可用的SEM，清洗要几分钟来完成。 </li><li>顺时针倾斜20°的SEM阶段，使得试样现在处于水平位置和垂直于电子束。如果样品是不平坦的，并且投射阴影到EBSD检测器荧光屏（例如使用FIB解除出来的TEM支撑格栅样品时），向后倾斜至10°或0°，以使样品倾斜从EBSD远探测器。 </li><li>设置最佳数据采集SEM条件:通过点击EHT（"超高压"）30千电子伏设置加速电压，选择EHT ON开启加速电压和选择的EHT的正确值。转至SEM控制面板的开口标签并选择高开口（ 例如，60或120微米），选择高电流模式或场模式（根据SEM）的深度并设置适当的电子束电流（大约3- 4nA的对于60微米的孔径和10-20 nA的一个120-μm的孔径）。 </li><li>通过改变样品的z位置带来在6至6.5毫米的工作距离的试样。 注意:这依赖于SEM和EBSD检测器的结构的图。样品应该只是上述荧光屏的顶部的水平定位。 </li><li>确保样品保持器平行于载物台的X轴，以避免对设备的可能损害，同时移动所述样本，并获得最佳的信号。 注意:不要仅通过看CCD相机对试样位置检查，在X方向移动标本，并确保与舞台的距离并没有改变。 </li><li>移动载物台来定位样本，并验证该束打在所关注的位置（将在其中执行所述TKD扫描），使用二次电子成像样品试样。 <ol><li>选择在DETECTO二次电子检测器的SEM控制面板的ř标签。 </li></ol></li><li>打开EBSD软件和通过按压EBSD相机的控制箱上的"在"按钮，从使用外部控制器或软件试样15至20毫米的距离插入EBSD相机。 </li><li>如果需要，可以分析，通过点击EDS相机控制面板上的"在"按钮插入腔室中的EDS检测。最佳位置可能不是相同的通常EDS分析，所以看信号计数，并确保死区时间是20至50％以便于最佳数据收集，以确定最佳的位置针对该特定实验设置。 注意:有可能在这种情况下，调整工作距离，以改善EDS的数据，但是，这将是在由EBSD相机收集衍射图样的质量为代价。 图2示出了用于数据采集，其中两个照相机EBSD的实验配置和EDS检测器已被插入到腔室中。 </li><li>一旦所有的检测器被定位和试样已被定位，通过选择在SEM控制面板的开口标签焦点摆动复选框并调节水平和垂直旋钮用于在控制板上的孔对准执行光束对准。进行焦点调节和通过调节水平和垂直旋钮用于在控制板上的stigmation像散校正。该步骤的目的是为了获得最清晰的图像成为可能。 注:在收集EDS数据一定要选择正确的试样架进行可靠的数据。不要使用由被分析的相同材料的试件支架，否则就无法区分从信号从样品架来的标本来的信号，并确保没有为衍射峰没有重叠，从被分析的材料和从该试样保持器是狂即</li></ol><img alt="图2" src="/files/ftp_upload/55506/55506fig2.jpg" /> 图2.实验装置。试样是在该级的旋转后水平位置。这限制了阶段和传送带与将所述EBSD相机的荧光屏上收集信号的干扰。 <a href="http://ecsource.jove.com/files/ftp_upload/55506/55506fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 3. EBSD软件参数进行数据采集注:数据采集参数是针对特定市售EBSD系统不同。这部分写成一般地，但一些这里给出的参数的名称和值都只是适当如果使用的材料清单中提到的EBSD软件，以及不同系统的用户12/112编辑根据自己的系统调整这些参数。大部分的步骤是完全一样的，作为一个正常的EBSD实验。 <ol><li>确保在EBSD软件的试样几何形状反映了试样处于水平位置。确保总倾角值是0°。如果不是，添加一个-20°的试样的几何形状标签预倾斜值。 </li><li>选择的相位（或多个）（其元素或化合物），以被分析为在相位标签正常EBSD实验。 </li><li>通过点击开始捕捉使用扫描图像选项卡中的EBSD软件的图像。 注:Forescatter安装在EBSD检测器荧光屏下面探测器可用于产生暗场图像，在薄区域和感兴趣的地点的识别辅助。 </li><li>通过直到图像较亮而不是过饱和，作为一个正常的EBSD experim优化增益和曝光值调整EBSD照相机，以便获得最佳的数据采集的设置耳鼻喉科，在优化模式选项卡。 注意:此步骤是依赖于样本和它的质量（厚度和表面光洁度）上。 </li><li>收集通过点击收集优化模式选项卡的背景。确保足够的晶粒存在用于通过调整放大倍数收集的背景资料，尽管它具有相似的厚度跨越区域扫描到的区域进行分析是很重要的。 </li><li>检查模式的质量，一旦背景已经通过确保静态的背景和自动背景选项已经被选中扣除。 <ol><li>虽然他们看起来失真，由于设置了特殊几何形状，确保衍射带清晰可见（ 见图3）。在EBSD照相机整合连续帧，以改善信噪比图像中，因为在荧光屏上的衍射图案的发光强度是低的。 </li><li>如果图案的质量不好够了，改变相机设置（调整增益和曝光）或改变SEM的孔径尺寸（如果可能使用较大的孔径）。它也可能是由于试样是在这种情况下减薄样品是唯一的解决方案（取决于试样，这可以通过使用FIB或离子减薄来进行上）太厚。 </li></ol></li></ol><img alt="图3" src="/files/ftp_upload/55506/55506fig3.jpg" /> 图3.通过TKD得到菊池衍射图。显示的图案失真相比于传统EBSD获得的图案和图案中心已向下移动。 <a href="http://ecsource.jove.com/files/ftp_upload/55506/55506fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <ol start="7"><li>优化模式识别求解器和通过进入优化求解器选项卡，以提高索引速度。 注:在T他在这里所使用的软件，有两种选择更好的TKD模式索引:优化TKD或成品精度。建议使用在衍射图案是高度离散化的优化TKD选项;为更高分辨率的图案（ 例如 336×256像素或更高），精制的精度模式效果最好。 </li><li>如果需要高分辨率分析（5纳米或更小的步长）离开在本设置中的样品30至60分钟，以改善真空和热稳定性光束。不要让光束虽然对感兴趣的区域。 </li><li>在开始数据采集之前，再次调整焦点和通过重复步骤2.11纠正SEM的散光。 </li><li>设置的参数（步长和地图的大小）在地图在Acquire地图数据标签采集。 注意:如果需要，步长大小可以是低到2纳米和如果试样是高质量的。 </li><li>通过在Acquire按下启动按钮，启动地图获取地图数据选项卡。 注:数据分析将开展完全相同的方式作为一个正常的EBSD扫描，无需调整。不同类型的地图可以从数据中获得。欧拉，带相反，反极图，相位图可以全部从收集的数据中获得。极图也可以从这些数据中得出。 </li></ol>

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The authors have nothing to disclose.

使用标准的，商业EBSD系统获得了本文所提出的所有数据。这样的系统是在世界上，这意味着，这种技术可以很容易地在这些实验室，而无需进行任何进一步的投资施加围绕许多实验室提供。在SEM的配置，并没有额外的软件无需修改是必要的，使用EBSD系统收集数据TKD。因此，从传统到EBSD TKD的过渡是很容易的。对于TKD的数据获取速率是类似的EBSD，目前达到至多约1000的图案/ s的19的。这种高率部分是由于扫描19在非常高的水平的技术中，包括校准图案中心位置和图案中心变化的自动化。 TKD将受益于所有这些优点。此外，像EBSD TKD，可以很容易地用EDS耦合，以获得额外的化学信息（参见图7）。 样品制备是非常重要的TKD以获得数据，因此时间应在步骤1.2花费以保证样品是足够薄以进行分析。否则，在开始实验没有意义的。适当设置SEM的参数是获得可靠的数据至关重要。用户应特别注意步骤2.5和2.11和值在协议中给出的参数可能需要进行调整，以特定的SEM，EBSD系统和标本。的参数，以优化模式识别（步骤3.7）也是以确保所收集的数据的质量好非常重要的。这些参数需要在该地区的不同区域的各种模式进行测试，以进行扫描，以确保感兴趣的完整区域可具有高索引率正常扫描。 在本文介绍的不同的例子证实了高分辨率与传统的EBSD比较的技术的能力。尽管用SEM和EBSD系统的硬件和软件方面取得的进展，在EBSD技术的分辨率不能低于20nm的高密度材料17，这意味着，在这些材料中表征特征小于50纳米的将是不可能达到的值。用更少的致密材料的工作将最小可分辨特征大小增加至100nm的标记。 图6b示出，它有可能使用TKD表征特征，例如存在于变形的Co-Cr-Mo合金，其是在10到20nm的小的HCP板条，因为该技术的空间分辨率可低至2纳米17。 地质材料通常是不导电的或半导电的，这往往带来一些困难，当他们需要使用传统的EBSD来表征。这个问题不存在本身，而ü唱TKD。在分析过程中的相互作用体积是如此之小给定试样的薄的几何形状，有导电性也没有问题。这个小的相互作用空间也是一个优点与高度变形材料工作时为常高的位错密度使得不可能获得可使用传统的EBSD被索引图案。如可在图8中可以看出，高度变形金刚石可以使用TKD尽管存在于其晶粒高位错密度来表征。 该技术的一个限制涉及的样品制备。这是很难获得良好的标本为TKD绝对比EBSD。样品制备技术是一样的TEM样品制备，这意味着它们是困难且耗时的。找到正确的区域来分析，也可以使用网站的具体技术，例如通过使用FIB它是否有足够的标本类型是有待解决的问题研究。空间分辨率与EBSD相比，他相当显著与跆拳道改善，但仍不如可以用TEM 17，19来实现的东西有多好。 本文已经证明，TKD是从不同的来源表征纳米晶和UFG材料有价值的技术。它更容易应用，速度，分辨率和灵活性电导率的术语超过在样品制备的难度。该技术的未来驻留在原位表征。 原位机械试验台使用而进行TKD分析，将有可能遵守这些纳米和超细微观结构下如何外部负载发生变化。这将增加对纳米晶和UFG材料的变形机制，我们的知识。

一个当今先进材料研究前沿的正在寻求积极设计量身定制的物理，化学和适合于高端应用的机械性能的材料。材料的微结构的修饰是调整其性能达到特定的高性能的有效方法。在这个范例中，提炼结晶材料的晶粒尺寸，以产生超细晶粒（UFG）或纳米晶材料已经被示出为增加其强度1，2的有效技术。这种细化的显微可以通过涉及严重的塑性变形3,4，工艺或通过合并超细或纳米尺寸的粉末成使用各种粉末冶金散装材料来实现处理5,6。这方面的研究已经INCreasing在过去的十年中，主要目标是扩大规模的过程，并了解这些材料的变形机制。 UFG和纳米晶材料，但是，并不是因为自然有其自己生产这种精致的晶体材料的方式仅限于现代应用在材料科学。地质断层区是已知的，以产生纳米晶区域;虽然常常假定为光显微镜研究的基础上无定形的，高分辨率透射电子显微镜（TEM）和扫描电子显微镜（SEM）分析经常表明晶粒尺寸可以在几十纳米7的规模。高应变速率变形发作，如那些在陨石影响，也可以产生纳米晶体结构，以及非常高的缺陷密度8。变形并不总是在自然界中的纳米结构的要求。 Pearce 等。 </EM&gt;已经在造山金矿通过Au及Pt / PTFE纳米颗粒的表征在从金矿9提取的矿物呈现从胶体源大量的金的沉积的证据。壳结构，如珍珠质，通过在几个100纳米10规模结晶单元的规则排列形成。甚至陨石已被证明含有UFG矿物结构11。 无论拥有这些UFG或纳米晶结构，其中表征材料的出处提出这促使改善表征工具的发展在纳米尺度是一个挑战。已调查了一个有希望的途径是电子显微镜。这样的技术出现完全适合此任务，由于固有的小的电子波长，与其使用相关的，提供给分析本草的原子结构的可能性L12的。前面已经表明，电子背散射衍射（EBSD）可用于表征与晶粒尺寸UFG材料下降到亚微米级13，14，15，16。然而，该技术EBSD的空间分辨率，即使使用当前最先进的SEM，这取决于材料17被限制在20至50纳米。因此，毫不奇怪，最初，研究人员试图解决方案通过使用TEM表征这些材料与超精细显微结构。结晶取向测定使用TEM衍射模式，例如菊池图案和点图案，可以达到10纳米，低于该值12，18，19某些情况下，顺序的空间分辨率。然而，一些缺点有蜜蜂n，其中使用这些技术来鉴定，如它们的速度和角分辨率，特别是当与通过EBSD 12,19提供的可能性。虽然基于自动旋进-TEM衍射技术可以实现类似的索引速度为EBSD，最TEM技术从自动化19的相对较低的水平受到影响。另外，通过TEM技术通常需要仪器的透镜系统的关键和耗时的路线，以实现最佳性能。 最近，兴趣已经转向提高SEM中的菊池衍射技术的分辨率，通过改变获得和分析信号的方式。 Keller和盖斯呈现在SEM 20进行低能透射菊池衍射的新形式。该方法中，他们命名传输EBSD（叔EBSD），必要的EBSD检测器和相关联的软件来捕获和分析在传输电子的大角度向前散射的角强度变化。使用该技术，他们能够从纳米颗粒和纳米颗粒与尺寸低至在直径为10nm收集菊池图案。在这种情况下分析的衍射电子经过试样和不喷出从试样的表面背面的事实，提示在术语的变化更适当地描述的技术;它现在被称为传输菊池衍射或TKD。跆拳道技术是由Trimby优化，允许更好的分辨率和自动获取定向图17。这种技术也可以用能量分散型X射线光谱法（EDS），耦合到收集化学信息而进行的结晶取向分析21。 本文提供了在设备方面的要求和标本进行TKD实验，描述了收集在四个不同的样品，以显示的技术的可能应用的范围内所必需的数据采集不同的步骤，并给出了结果。这里介绍的例子是已受到严重的塑性变形来创建UFG /纳米晶材料或也受到严重的塑性变形和本细化的显微地质材料或者金属合金。

<table><tbody><tr><td>Scanning electron microscope</td><td>&amp;nbsp;Zeiss&amp;nbsp;</td><td></td><td>Preferably equipped with a&amp;nbsp; field emission source in order to maximize spatial resolution. The one used here is a Zeiss Ultra plus field emission-SEM</td></tr><tr><td>Electron backscatter diffraction detector</td><td>Oxford instruments</td><td></td><td>Different system are available on the market. The one is in this work is a Nordlys-nano EBSD detector from Oxford instruments. Forescatter detectors are mounted belown the detector phospor screen which is an option.</td></tr><tr><td>Electron backscatter diffraction software for data acquisition and analysis</td><td>Oxford instruments</td><td></td><td>The protocal is described here for the usage of the AZtecHKL EBSD software but other software can be used as well</td></tr><tr><td>EDS detector</td><td>Oxford instruments</td><td></td><td>This is optional. The one used here is a X-Max 20&amp;nbsp;mm&lt;sup&gt;2&lt;/sup&gt; silicon drift EDS detector from Oxford instruments</td></tr><tr><td>sample holder for TKD</td><td>ANY</td><td></td><td>As long as it can handle thin specimen and can be placed in the correct orientation within the microscope. Different companies sell specific sample holders for TKD analysis if required by the user.</td></tr><tr><td>Plasma cleaner</td><td>Evactron</td><td></td><td>This is optional. The one used here is Evactron Model 25 RF Plasma Decontaminator for FIB/SEM and Vacuum Chambers</td></tr></tbody></table>

characterization of ultra-fine grained and nanocrystalline materials using transmission kikuchi diffraction

其中的微观结构分析中的挑战如今居住在超细晶粒（UFG）和纳米材料的可靠和准确的表征。用扫描电子显微镜（SEM）相关的传统技术，例如电子背散射衍射（EBSD），不具备所要求的空间分辨率由于从束中的电子和材料的原子之间的相互作用大体积。透射电子显微镜（TEM）具有所需的空间分辨率。然而，由于在分析系统中缺乏自动化的，数据采集的速率是缓慢的，其限制了可以被表征试样的区域。本文提出了一种新的表征技术，传输菊池衍射（TKD），这使得能够UFG和使用SEM纳米晶体材料的配备标准EBSD系统微结构的分析。该技术的空间分辨率能达到2纳米。这种技术可以应用于大范围的材料，这将是难以用传统EBSD分析。呈现所述实验设置和描述必要实现一种TKD分析的不同步骤之后，示出其上的金属合金和矿物质的使用例子来说明该技术的分辨率和它的材料的术语灵活性来表征。

这里给出的数据已经使用的材料清单中提到的SEM，EBSD系统和软件的收集。根据感兴趣的功能，扫描，用不同的步长运行和特定步长表示对这项工作表示每个样本。 这里提出TKD应用程序的两个第一实施例是为了增加它们的机械性能与金属合金的晶粒细化。不锈钢和钴-铬-钼合金通常用于生物医学应用，由于其高耐腐蚀性，承受静载荷和生物相容性23,24良好的机械性能。然而，这两种材料都具有缺点:不锈钢具有低的硬度和耐磨性，同时的Co-Cr-Mo合金可以由于摩擦腐蚀现象失败。一种方法ŤO地址这些材料缺憾是由组织细化，以改变其表面性质。不锈钢和Co-Cr-Mo合金试样进行表面机械研磨（SMAT），这是一种表面处理产生，由严重的塑性变形，可提高该表面机械纳米晶体表面层，摩擦学，和腐蚀特性散装材料，而不改变它们的化学组成25。使用TKD，处理过的表面下方的微观结构进行了分析了不同的材料微观结构的改变链接到改善的性质。 使用TKD微观结构表征已经证明，使不锈钢试样SMAT创建的区域，1微米厚的经处理的表面，在那里和稍微拉长纳米颗粒等轴纳米颗粒的混合物存在23的下方。图4呈现的是被一个上处理的样品运行TKD扫描中的一个。在TKD试样通过使用FIB作为感兴趣的区域只是在样品的表面上制备。 图4示出的是，在处理过的表面下方的第一区域中，等轴晶的直径小于100nm，而100至200nm;长度可以达到500nm的细长晶粒本厚度。低于该第一区域中，细长亚微米尺寸的晶粒的UFG区域也可以看到该图。这是第一次，纳米晶区域被正确其特征在于经受SMAT试样。为了进行比较，在遭受SMAT使用传统EBSD和扫描中的一个的结果进行分析不锈钢另一个试样示于图5。两个带的对比度和IPF地图显示的UFG区域的表面处的存在。然而，虽然15nm的步长大小来运行扫描，晶粒<html> S IN该区域不能被成功索引由于是在每个位置在扫描期间分析的更大的相互作用空间。这显示了EBSD技术的用于表征UFG和纳米晶材料的极限。 <img alt="图4" src="/files/ftp_upload/55506/55506fig4.jpg" /> 从SMAT后的不锈钢试样收集图4. TKD数据。中的数据使用5nm的步长上的100至120nm厚的样品收集。 （ 一 ）频带对比图给出收集模式（灰度轻越好的图案）的质量的指示; （b）中反极图（IPF）地图显示根据在地图上的右侧所表示的颜色方案的晶粒的不同的晶体取向。处理的表面是在地图上的顶部。ARGET ="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图5" src="/files/ftp_upload/55506/55506fig5.jpg" /> 从SMAT后的不锈钢试样收集图5 EBSD数据。中的数据使用15nm的步骤中收集。 （ 一 ）频带合同图; （b）中 IPF图。 <a href="http://ecsource.jove.com/files/ftp_upload/55506/55506fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 图6示出进行SMAT的Co-Cr-Mo合金样品的TKD表征的结果。使用FIB制备TKD试样和分析区域位于被处理表面下方大约10微米。结果表明，该组织的细化通过相变24发生。最初，材料所具有的单个面心立方（FCC）相，并且具有10μm的平均晶粒尺寸。 图6示出，在该变形区域中的两个相存在:六方紧密堆积（hcp）板条看到的面心立方晶内。这些板条的厚度可以小至10至20纳米。微观结构的该改进解释了材料刚刚处理过的表面24下方的测得的硬度的增加三倍。 <img alt="图6" src="/files/ftp_upload/55506/55506fig6.jpg" /> 从SMAT后钴-铬-钼合金样品收集图6. TKD数据。中的数据使用5nm的步长上的100至120nm厚的样品收集。 （ 一 ）频带对比图; （b）中的相位图表示存在于塑性变形后的合金的两个相的分布，红色颜色表示的hcp相，而蓝色表示FCC相; （c）中 IPF图表示根据地图上的左侧表示的颜色方案的HCP相的晶粒的不同的结晶取向; （d）中IPF图示出了根据在地图上的右侧所表示的颜色方案FCC相的晶粒的不同的晶体取向。 <a href="http://ecsource.jove.com/files/ftp_upload/55506/55506fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 这里介绍的最后两个例子都涉及到地质学领域。亚微米的结构可以存在于矿物由于它们在地球地幔内或在地震进行，例如，严重的塑性变形。这些材料可呈现高的位错密度，使用户使用传统的表征人EBSD不可能的。微观结构的详细研究是至关重要的。然而，以确定这些矿物质的背景，了解不同的化学和物理过程，以他们已进行。例如，可以通过研究金刚石及其包裹跟随地球深部碳循环。 图7示出这些研究中的一个，其中，Jacob 等。调查的FeNi-硫化物系夹杂物的显微组织和组成在显示纳米颗粒状磁铁矿反应电晕26的多晶金刚石聚集体。在TKD分析表明存在于样品中（ 图7b）的不同阶段的分布，并显示出磁铁矿（ 图7a）的纳米结构。通过用EDS，第内的不同元素（在此示出在图7c和D仅铁，铜分布）的分布耦合TKD<html> È不同阶段被确定。该研究证明，金刚石形成，并且通过涉及金刚石成形流体和形成磁铁矿和金刚石26的FeNi硫化物的氧化还原反应成核。 <img alt="图7" src="/files/ftp_upload/55506/55506fig7.jpg" /> 图7. TKD，并在多晶金刚石聚集体从铁-镍合金，硫化物系夹杂物收集EDS数据。中的数据使用10nm的步长在80至100nm厚的样品收集。 （ 一 ）频带对比图; （b）是表示存在于样品中的不同阶段的分布相位图，金刚石以黄色，磁铁矿在红色，磁黄铁矿中的绿色和黄铜矿在蓝色表示; （c）表示Fe的样本分布的化学组成图; （d）表示Cu的试样中的分布的化学组成图。EF ="http://ecsource.jove.com/files/ftp_upload/55506/55506fig7large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 许多地质样品进行高塑性变形，尽管这不总是与地球的构造过程相关联。在地球表面上的许多陨石坑观测到撞击构造，偶尔有足够高的压力相关的改造石墨转变为钻石27。这些钻石的结构高度具有非常高的位错密度变形由于由陨石高能量冲击。 图8示出冲击钻的一个例子使用TKD表征。由样品中看到的大的塑性变形解释亚微米尺寸的颗粒的存在，双胞胎的高比例（参见图8b）和晶体取向的梯度瓦特ithin晶粒（这些梯度是由于在晶粒内高的位错密度）。 <img alt="图8" src="/files/ftp_upload/55506/55506fig8.jpg" /> 图8从一个陨石撞击金刚石收集TKD数据。中的数据使用10nm的步长在80至100nm厚的样品收集。的（a）带坡度图给出收集模式（灰度打火机的图案越好）的质量的指示; （b）中 IPF图示出了根据在地图上的右侧所表示的颜色方案的晶粒的不同的晶体取向。的红线代表孪晶界，一个60°旋转约&lt;111&gt;。 <a href="http://ecsource.jove.com/files/ftp_upload/55506/55506fig8large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction at JoVE.com

Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction

本文提供的详细方法来表征使用装备有标准电子背散射衍射系统的扫描电子显微镜超细晶粒和纳米晶材料的微观结构。金属合金和矿物质呈现细化的显微使用进行分析该技术中，示出了其可能的应用的多样性。

超细晶和纳米晶材料的表征采用透射菊池衍射

One of the challenges in microstructure analysis nowadays resides in the reliable and accurate characterization of ultra-fine grained (UFG) and ...

characterization-ultra-fine-grained-nanocrystalline-materials-using

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SCIENTISTS IN ACTION

13.3K 次观看.  The University of Sydney. 本文提供的详细方法来表征使用装备有标准电子背散射衍射系统的扫描电子显微镜超细晶粒和纳米晶材料的微观结构。金属合金和矿物质呈现细化的显微使用进行分析该技术中，示出了其可能的应用的多样性。 

视频: Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

在极端的压力和温度的合成和Microdiffraction

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

科研

工程学

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

使用拉曼光谱与多颗粒的声子坐月子型号纳米大小分布的特征

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

The optical, electrical, and structural properties of dislocations and of grain boundaries in semiconductor materials can be determined by experiments performed in a scanning electron microscope. Electron microscopy has been used to investigate cathodoluminescence, electron beam induced current, and diffraction of backscattered electrons.

通过扫描电子显微镜在半导体材料的扩展缺陷的全面表征

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications ...

High Pressure Single Crystal Diffraction at PX^2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe2+0.14Fe3+0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 &#177;0.006 &#197;, b = 8.761 &#177;0.004 &#197;, c = 5.248 &#177;0.001 &#197;, &#946; = 105.06 &#177;0.03&#186;, &#945; = &#947; = 90&#186;.

In this report, we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell at the GSECARS 13-BM-C beamline at the Advanced Photon Source. ATREX and RSV programs are used to analyze the data.

高压单晶衍射PX ^ 2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the ...

化学

Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene

The precise details of the interaction of intense X-ray pulses with matter are a topic of intense interest to researchers attempting to interpret the results of femtosecond X-ray free electron laser (XFEL) experiments. An increasing number of experimental observations have shown that although nuclear motion can be negligible, given a short enough incident pulse duration, electronic motion cannot be ignored. The current and widely accepted models assume that although electrons undergo dynamics driven by interaction with the pulse, their motion could largely be considered &#39;random&#39;. This would then allow the supposedly incoherent contribution from the electronic motion to be treated as a continuous background signal and thus ignored. The original aim of our experiment was to precisely measure the change in intensity of individual Bragg peaks, due to X-ray induced electronic damage in a model system, crystalline C60. Contrary to this expectation, we observed that at the highest X-ray intensities, the electron dynamics in C60 were in fact highly correlated, and over sufficiently long distances that the positions of the Bragg reflections are significantly altered. This paper describes in detail the methods and protocols used for these experiments, which were conducted both at the Linac Coherent Light Source (LCLS) and the Australian Synchrotron (AS) as well as the crystallographic approaches used to analyse the data.

We describe an experiment designed to probe the electronic damage induced in nanocrystals of Buckminsterfullerene (C60) by intense, femtosecond pulses of X-rays. The experiment found that, surprisingly, rather than being stochastic, the X-ray induced electron dynamics in C60 are highly correlated, extending over hundreds of unit cells within the crystals1.

在纳米富勒的飞秒衍射实验的长程电子关联的测量

The precise details of the interaction of intense X-ray pulses with matter are a topic of intense interest to researchers attempting to interpret the ...

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.

矿物和岩石样品的同步辐射 x 射线 Microdiffraction 和荧光成像

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder ...

Microcrystal Electron Diffraction of Small Molecules

A detailed protocol for preparing small molecule samples for microcrystal electron diffraction (MicroED) experiments is described. MicroED has been developed to solve structures of proteins and small molecules using standard electron cryo-microscopy (cryo-EM) equipment. In this way, small molecules, peptides, soluble proteins, and membrane proteins have recently been determined to high resolutions. Protocols are presented here for preparing grids of small-molecule pharmaceuticals using the drug carbamazepine as an example. Protocols for screening and collecting data are presented. Additional steps in the overall process, such as data integration, structure determination, and refinement are presented elsewhere. The time required to prepare the small-molecule grids is estimated to be less than 30 min.

Here, we describe the procedures developed in our laboratory for preparing powders of small molecule crystals for microcrystal electron diffraction (MicroED) experiments.

小分子的微晶电子衍射

A detailed protocol for preparing small molecule samples for microcrystal electron diffraction (MicroED) experiments is described. MicroED has been ...

生物化学

Determining the Mechanical Strength of Ultra-Fine-Grained Metals

The mechanical strengthening of metals is the long-standing challenge and popular topic of materials science in industries and academia. The size dependence of the strength of the nanometals has been attracting a lot of interest. However, characterizing the strength of materials at the lower nanometer scale has been a big challenge because the traditional techniques become no longer effective and reliable, such as nano-indentation, micropillar compression, tensile, etc. The current protocol employs radial diamond-anvil cell (rDAC) X-ray diffraction (XRD) techniques to track differential stress changes and determine the strength of ultrafine metals. It is found that ultrafine nickel particles have more significant yield strength than coarser particles, and the size strengthening of nickel continues down to 3 nm. This vital finding immensely depends on effective and reliable characterizing techniques. The rDAC XRD method is expected to play a significant role in studying and exploring nanomaterial mechanics.

The protocol presented here describes the high-pressure radial diamond-anvil-cell experiments and analyzing the related data, which are essential for obtaining the mechanical strength of the nanomaterials with a significant breakthrough to the traditional approach.

测定超细晶粒金属的机械强度

The mechanical strengthening of metals is the long-standing challenge and popular topic of materials science in industries and academia. The size ...

Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2

The KWS-2 SANS diffractometer is dedicated to the investigation of soft matter and biophysical systems covering a wide length scale, from nm to &#181;m. The instrument is optimized for the exploration of the wide momentum transfer Q range between 1x10-4 and 0.5 &#197;-1 by combining classical pinhole, focusing (with lenses), and time-of-flight (with chopper) methods, while simultaneously providing high-neutron intensities with an adjustable resolution. Because of its ability to adjust the intensity and the resolution within wide limits during the experiment, combined with the possibility to equip specific sample environments and ancillary devices, the KWS-2 shows a high versatility in addressing the broad range of structural and morphological studies in the field. Equilibrium structures can be studied in static measurements, while dynamic and kinetic processes can be investigated over time scales between minutes to tens of milliseconds with time-resolved approaches. Typical systems that are investigated with the KWS-2 cover the range from complex, hierarchical systems that exhibit multiple structural levels (e.g., gels, networks, or macro-aggregates) to small and poorly-scattering systems (e.g., single polymers or proteins in solution). The recent upgrade of the detection system, which enables the detection of count rates in the MHz range, opens new opportunities to study even very small biological morphologies in buffer solution with weak scattering signals close to the buffer scattering level at high Q.
In this paper, we provide a protocol to investigate samples with characteristic size levels spanning a wide length scale and exhibiting ordering in the mesoscale structure using KWS-2. We present in detail how to use the multiple working modes that are offered by the instrument and the level of performance that is achieved.

Here, we present a protocol to investigate soft matter and biophysical systems over a wide mesoscopic length scale, from nm to &#181;m that involves the use of the KWS-2 SANS diffractometer at high intensities and an adjustable resolution.

在小角度中子衍射仪KWS-2研究软物质和生物系统在广泛的长度尺度从纳米，微米尺寸

The KWS-2 SANS diffractometer is dedicated to the investigation of soft matter and biophysical systems covering a wide length scale, from nm to &#181;m. ...

生物工程

Quantitative Atomic-Site Analysis of Functional Dopants/Point Defects in Crystalline Materials by Electron-Channeling-Enhanced Microanalysis

A novel elemental and chemical analysis scheme based on electron-channeling phenomena in crystalline materials is introduced, where the incident high-energy electron beam is rocked with the submicrometric pivot point fixed on a specimen. This method enables us to quantitatively derive the site occupancies and site-dependent chemical information of impurities or intentionally doped functional elements in a specimen, using energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy attached to a scanning transmission electron microscope, which is of significant interest to current materials science, particularly related to nanotechnologies. This scheme is applicable to any combination of elements even when the conventional Rietveld analysis by X-ray or neutron diffraction occasionally fails to provide the desired results because of limited sample sizes and close scattering factors of neighboring elements in the periodic table. In this methodological article, we demonstrate the basic experimental procedure and analysis method of the present beam-rocking microanalysis.

We provide a general outline of quantitative microanalysis methods for estimating the site occupancies of impurities and their chemical states by taking advantage of electron-channeling phenomena under incident electron beam-rocking conditions, which reliably extract information from minority species, light elements, oxygen vacancies, and other point/line/planar defects.