这项工作得到斯洛伐克研究和发展局根据合同编号的支持。APVV-16-0079 和 APVV-15-0621, 赠款维加 1/0182/16 和维加 2/0082/17 和 Palacký大学的内部 IGA 赠款 (IGA_PrF_2018_002)。我们感谢 R. Rüffer (ESRF, 格勒诺布尔) 为同步辐射实验提供帮助。

1. 镁的制备
注: 为了演示 NFS 与穆斯堡尔光谱的广泛诊断能力, 设计了适当的镁成分, 即 (Fe3Co1)76钼8铜1B15 (在 .%)。该系统显示了从铁磁向顺磁态过渡到结晶开始的磁场。此外, 晶粒在第一结晶过程中出现, 形成 bcc-铁, Co 相。因为钴在 bcc 格子的某些原子位置替换铁, 偏差在各自超精细相互作用发生。
<ol><li>熔体的制备 注: 穆斯堡尔光谱和 NFS 扫描的地方原子安排通过超精细相互作用的57Fe 核是存在于调查样本。这稳定的核素的自然丰盈在所有 Fe 同位素之中是, 然而仅2.19%。为了减少原位NFS 实验的采集时间, 57铁同位素的相对含量应提高到约50%。<ol>
<li>采用石英玻璃坩埚 (直径为15毫米的圆柱形), 用氮化硼覆盖其内壁, 以避免硅从墙壁中对其含量进行可能的污染, 并插入0.4050 克高浓缩57Fe (~ 95%) 和0.5267 克标准电解纯铁 (纯度 99.95%) 到这个坩埚。该混合物的总质量为0.9317 克, 保证了 50% 57Fe 的同位素富集。 注: 由于稳定的57Fe 同位素的高价格, 优化其数量到尽可能低的质量。大约500毫克57Fe 应该是足够保证熔化的整体重量到大约 1.5 g。这是制备设备的低技术极限。</li>
		<li>将0.3245 克电解 Co (99.85%)、0.0184g 铜 (99.8%)、0.2222 克钼 (99.95%) 和0.0470 克晶体 B (99.95%) 加入同一个石英玻璃坩埚中。混合物的总质量是 1.5438 g, 并且粉末的意欲的构成是 (Fe3Co1)76钼8铜1B15。</li>
		<li>在保护氩 (4N8) 气氛下, 在石英玻璃坩埚中通过感应加热熔化所获得的标准电解材料混合物, 以避免氧化, 并使用90-120 赫的射频场。 注: 射频场确保坩埚中各元件的混合。当熔体形成时, 它们的混合在涡流的帮助下进一步进行。允许足够的时间融化粉末混合物, 形成液体。目视检查是足够的, 没有必要测量产生的液体的温度。</li>
		<li>从坩埚中取出所获得的小锭。目视检查其表面的任何痕迹的出现。如果存在, 通过机械抛光去除。</li>
	</ol></li>
	<li>带状状试样的制备
	<ol>
<li>使用用于平面流铸件的装置。图 1显示了这样一个设备的示例。 注: 石英管内的熔体被 Ar 流排出到在空气中旋转的淬火轮上。不需要特殊的大气条件下, 淬火车轮的操作 (如真空或惰性气体环境) 的这一组成的熔融。</li>
		<li>由于钢锭的重量小 (~ 1.5 克), 选择一个具有喷嘴直径为0.8 毫米圆孔的石英管。把钢锭放进去, 用感应加热熔化。保持熔化的温度在 1,280-1, 295 °c。</li>
		<li>将冷却轮的表面速度调整到40米/秒。</li>
		<li>在环境条件下,即空气中, 将熔体铸造在旋转淬火轮上。 注: 产生的丝带约 1.5-2 毫米宽, 25-27 µm 厚, 5 米长。丝带的空气边, 在生产期间被暴露对周围的空气大气, 是光学上发亮的 (光泽), 而相反轮子边, 与淬火轮子直接地接触, 是垫 (沉闷)。这些微妙的丝带质量是由熔体的低质量造成的。因此, 由于单个元素的输入质量低, 验证所生产的淬火带的最终化学成分是很重要的。</li>
	</ol></li>
	<li>验证色带的最终化学成分
	<ol>
<li>准备几个 (多达五) 短片的丝带, 每个有约0.70 毫克的质量. 从所生产的丝带的不同部分, 沿其长度选择。</li>
		<li>将每条丝带溶解在1毫升的浓缩中 (67%)HNO3酸, 充水达到50毫升的溶液总容积。</li>
		<li>用电感耦合等离子体 (ICP) 光学发射光谱法测定钼和 B 的含量。使用仪器手册中提供的外部校准方法。用以下波长记录信号: Mo 在203.844 毫微米和204.598 毫微米, 并且 B 在249.773 毫微米。</li>
		<li>火焰原子吸收光谱法测定铁、钴、铜的含量。使用仪器手册中提供的外部校准方法, 并选择这些波长: Fe 在248.3 毫微米, Co 在240.7 毫微米, 并且铜在324.7 毫微米。</li>
	</ol></li>
	<li>生产带的结构表征
	<ol>
<li>通过在布拉格-布伦塔诺几何中执行 X 射线衍射 (XRD) 检查产生的色带的非晶性;使用波长为 0.154056 nm 的铜阳极, 记录 2Θ20-100°的衍射模式, 0.05°和采集时间为一点。 注: 非晶态试样的 XRD diffractogram 特征是像图 2所示的宽反射峰。没有窄线表明存在的晶粒应该存在。</li>
		<li>准备小块的生产丝带, 总质量约3-5 毫克, 并把它们放入一个石墨坩埚的 DSC 设备。 注: 长度约2毫米的小块可以用剪刀从丝带上剪下来。</li>
		<li>在 Ar 气氛下, 在50-700 摄氏度的温度范围内, 执行 DSC 实验, 温度斜坡为 10 K/分钟。</li>
		<li>确定结晶 Tx1的起始温度, 这是在 DSC 曲线上最显著峰值的扭结处进行的。 注: 结晶 Tx1的起始温度在图 3中用箭头表示。</li>
		<li>选择了五的退火温度, 覆盖 DSC 上的预结晶和结晶区, 进一步进行原位退火。 注: 在我们的情况下, 适当的温度是 370, 410, 450, 510 和550°c, 如图 3所示。</li>
	</ol></li>
	<li>原位退火<ol>
<li>准备五组7厘米长的片 (总长度) 的淬火丝带。各自的丝带应该是至少 1 cm 长。</li>
		<li>对于原位退火, 使用炉 (图 4)。设置目标温度, 并等待15分钟的稳定。 注: 炉体设计保证了等温退火的最小起效时间。该炉由两部分组成: 上、下圆形大型镀镍铜块, 作为温度均质体。Kanthal 一条带热的块, 温度调节和稳定的高动态。目标温度是在步骤1.4.5 中确定的。</li>
		<li>将带状件插入到疏散和热稳定区。要做到这一点, 在两个方块之间打开一个7-10 毫米的缝隙, 并将丝带直接滑入加热区的中心。</li>
		<li>立即关闭缺口。这样, 试样的温度在 0.1 K 的差值内达到5秒的炉膛温度。</li>
		<li>在真空下进行370、410、450、510和550摄氏度的退火, 以防止表面氧化。</li>
		<li>退火后, 取下加热的丝带, 放在真空系统内的冷基板上。这保证了样品的快速冷却到室温。 注: 热处理后的缎带诱导结构的变化, 最终导致结晶的最初无定形材料。</li>
	</ol></li>
</ol>2. 调查方法
<ol><li>
穆斯堡尔光谱 注: 使用的铁丰富到约50% 在57Fe 生产的研究 MG 确保足够短的采集时间的原位NFS 实验。另一方面, 有效厚度的丝带明显增加。这就造成了与传统透射几何实验中记录的吸收穆斯堡尔谱线极高的展宽有关的问题。这就是为什么要考虑穆斯堡尔光谱的表面敏感技术。即转换电子穆斯堡尔光谱分析 (CEMS) 和转换 X 射线穆斯堡尔光谱分析 (CXMS) 可以应用。虽然 CEMS 扫描地下区域到大约200毫微米的深度, CXMS 提供信息从更深的区域延伸到大约5-10 µm。<ol>
<li>为 CEMS/CXMS 实验准备样品;用6-8 块1厘米长的丝带做一个样品。</li>
		<li>将丝带并排连接到铝架上, 形成紧凑面积约 1 x 1 厘米2;在丝带的两端使用胶带;所有丝带必须放在他们的空气两侧向上。 注: 确保缎带与持有人之间有电接触, 样品的中心部分 (约 8 x 10 毫米2) 从任何表面污染中清除,例如胶带的残留物。</li>
		<li>将铝持有者与样品插入 CEMS/CXMS 探测器。</li>
		<li>在测量之前, 用检测气体的流彻底清洗内部检测器体积, 以排出所有残余空气。允许10-15 分钟完成此过程。</li>
		<li>用针阀将气体流量通过检测器调整到3毫升/分。</li>
		<li>将高电压连接到探测器: 典型值为 CEMS 约1.2 伏, CXMS 高约200伏。</li>
		<li>使用装有57Co/Rh 放射源的恒定加速度光谱仪记录 CEMS 和 CXMS 穆斯堡尔谱。根据说明书在室温下使用气体检测仪操作光谱仪。</li>
		<li>分别用4和 Ar + ch4气体混合物填充气体探测器, 完成对转换电子和 X 射线的检测。在两种情况下, 将 CH4的数量保持在10%。</li>
		<li>重复步骤2.1.2 到2.1.8 的车轮侧的调查的丝带。</li>
		<li>使用薄 (12.5 µm) α Fe 箔对仪器进行速度校准14 。</li>
		<li>评价 CEMS/CXMS 谱;在校准α-Fe 箔的室温穆斯堡尔谱上引用获得的异构体移位值。 注: 获得的穆斯堡尔谱可以通过任何合适的拟合代码进行评估, 例如由煨软件24。</li>
	</ol>
</li>
	<li>
Nfs
	<ol>
<li>在同步加速器上使用合适的核磁共振光束线完成 NFS 实验。一个可能的选择: ID 18 在欧洲同步辐射设施 (ESRF) 在格勒诺布尔, 法国。25
</li>
		<li>将光子光束的能量调至14.413 凯文, 带宽为1兆伏特。</li>
		<li>在真空炉内放置被调查的镁的大约6毫米长的丝带。</li>
		<li>在样品的连续加热过程中记录 NFS 时间域模式, 温度可达700摄氏度, 斜坡为 10 K/分钟. 在整个原位退火过程中, 使用1分钟的时间间隔来获取实验数据。 注意: NFS 实验的传输几何可以确保从样本的批量获取有关超精细交互的信息。</li>
		<li>使用合适的软件 (如www.nrixs.com) 评估 NFS 实验数据。 注意: 在一次原位实验中, 通常会记录多达100个 NFS 时间域模式。在 CONUSS 软件包26、27的评估过程中, 考虑应用一个名为休伯特的特殊自由软件, 它可以在半自动模式28中评估如此巨大的数据量。</li>
	</ol>
</li>
</ol>

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<li>Sturhahn, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((CONUSS+and+PHOENIX%3A+Evaluation+of+nuclear+resonant+scattering+data%5BTitle%5D)+AND+%22Hyperfine+Interact%22%5BJournal%5D)">CONUSS and PHOENIX: Evaluation of nuclear resonant scattering data.</a> Hyperfine Interact. 125 (1-4), 149-172 (2000).</li>
<li>Vrba, V., Procházka, V., Smrčka, D., Miglierini, M. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0168900216312037">Advanced Approach to the Analysis of a Series of in-situ Nuclear Forward Scattering Experiments.</a> Nucl. Instr. Meth. Phys. Res. A. 847, 111-116 (2017).</li>
<li>Miglierini, M., Grenèche, J. -M. <a target="_blank" href="http://iopscience.iop.org/article/10.1088/0953-8984/9/10/017">Mössbauer Spectrometry of Fe(Cu)MB-Type Nanocrystalline Alloys: I. The Fitting Model for the Mössbauer Spectra.</a> J. Phys.: Condens. Matter. 9 (10), 2303-2319 (1997).</li>
<li>Mülhaupt, G., Rüffer, R. <a target="_blank" href="https://link.springer.com/article/10.1023/A:1017055403261">Properties of synchrotron radiation.</a> Hyperfine Int. 123 (1-8), 13-30 (1999).</li>
<li>Rüffer, R. <a target="_blank" href="https://www.sciencedirect.com/science/article/pii/S1631070507001338">Nuclear resonance scattering.</a> C. R. Physique. 9 (5-6), 595-607 (2008).</li>
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<li>Machala, L., Procházka, V., Miglierini, M., Sharma, V. K., Marušák, Z., Wille, H. -C. h, Zbořil, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Direct+Evidence+of+Fe%28V%29+and+Fe%28IV%29+Intermediates+during+Reduction+of+Fe%28VI%29+to+Fe%28III%29%3A+A+Nuclear+Forward+Scattering+of+Synchrotron+Radiation+Approach%5BTitle%5D)+AND+%22Phys.+Chem.+Chem.+Phys%22%5BJournal%5D)">Direct Evidence of Fe(V) and Fe(IV) Intermediates during Reduction of Fe(VI) to Fe(III): A Nuclear Forward Scattering of Synchrotron Radiation Approach.</a> Phys. Chem. Chem. Phys. 17 (34), 21787-21790 (2015).</li>
</ol>

作者没有什么可透露的。

前现场穆斯堡尔效应实验描述了在应用热处理后, 在所研究的 MG 中遇到的稳态情况。每种光谱都是在室温下连续数小时收集的。因此, 最初的非晶态结构的演化是作为退火条件的函数来遵循的。由于穆斯堡尔光谱对共振核作用下的超精细相互作用很敏感, 所以可以揭示温度升高引起的结构和/或磁性修正的微弱细节。然而, 当临时改变的条件 (如温度升高) 的影响已经完成时, 在环境条件...

由熔体快速淬火制备的铁基 mg 代表工业上有吸引力的材料与许多实际应用1。特别是因为它们的磁性能往往优于常规 (多晶硅) 晶体合金2,3。为了更好地从它们的有利参数中获益, 应该知道它们对高温的反应。随着温度的升高, 无定形结构松弛, 最终结晶开始。在某些类型的, 这可能导致其磁性参数的恶化, 因此, 性能较差。然而, 有几个家庭的铁基的铁人与特殊成分4,5,6,7 , 其中新形成的水晶谷物是非常精细的, 通常低于约30毫微米的大小。纳米晶能稳定结构, 从而在宽温度范围8、9保持可接受的磁性参数。这些是所谓的纳米晶合金 (NCA)。
在高温和/或恶劣条件下 (电离辐射、腐蚀等) 的长期性能可靠性要求对其行为和个别物理参数有透彻的了解。由于是无定形的, 分析技术的分类是相当有限的。例如, 衍射方法提供了广泛和无特色的反射, 只能用于验证 amorphicity。
值得注意的是, 有几种, 通常是间接的方法, 提供快速和无损的特性,例如, 磁致伸缩延时线传感原理。该方法提供了结构和应力状态的快速表征, 包括不均匀性的存在。它有利地适用于快速和非破坏性的描述沿镁丝带10,11的整个长度。
更详细的洞察到无序的结构安排可以通过超精细相互作用, 敏感地反映共振原子的局部原子安排来实现。此外, 还可以揭示拓扑和化学短距离阶的变化。在这方面, 在57Fe 核上进行的核磁共振 (NMR) 光谱分析和/或穆斯堡尔光谱分析的方法应该被认为是12,13。前者的方法只对磁偶极子超精细相互作用提供响应, 后者对电四极相互作用也很敏感。因此, 穆斯堡尔分光光度法同时提供了共振铁核14的结构布置和磁态的同时可用信息。
然而, 为了获得合理的统计数据, 穆斯堡尔频谱的获取通常需要几个小时。这一限制应特别考虑到温度依赖性实验的设想。在实验过程中应用的高温导致了研究的15的结构修改。因此, 只有在室温下进行的原位实验, 在一定温度下进行退火, 然后返回到环境条件下, 才能提供可靠的结果。
在热处理过程中, 镁结构的演变是通过分析技术进行的, 这种方法可以快速获取数据, 例如同步辐射 (DSR) 的 X 射线衍射, 差分扫描量热 (DSC), 或磁性测量。虽然现场实验是可能的, 获得的信息涉及结构 (DSR, DSC) 或磁性 (磁性数据) 的特点。然而, 在 DSC (和磁性测量) 的情况下, 在结晶过程中出现的 (纳米) 晶粒的识别是不可能的。另一方面, DSR 数据并不表示所调查系统的磁状态。这种情况的解决方案是利用超精细交互的技术: 同步辐射16的 NFS。它属于一组利用核共振散射过程17的方法。由于从第三代同步辐射获得的辐射极高的光辉,在原位条件下的温度 NFS 实验成为可行的18,19,20,21 ,22,23。
穆斯堡尔光谱和 NFS 都受与57铁核能级之间的核共振有关的物理原理所制约。然而, 虽然前者扫描超精细在能源领域的互动, 后者提供干涉的时间域。这样, 从两种方法得到的结果是等价的和互补的。为了评估 NFS 数据, 必须建立一个合理的物理模型。这项具有挑战性的任务可以通过提供第一个估计的穆斯堡尔光谱的帮助来完成。这两种方法的互补性意味着,原位NFS 检查瞬态状态和穆斯堡尔谱反映了稳定状态,即研究的材料的初始和/或最终状态。
本文详细介绍了这两种不常用的核共振方法的应用: 在这里, 我们将它们应用于在 a (Fe2.85Co1)77钼8铜1中发生的结构修改的调查.B14毫克接触热处理。我们希望这篇文章吸引研究人员的兴趣, 利用这些技术来调查类似的现象, 最终用不同类型的材料。

<table><tbody><tr><td>stable isotope, &lt;sup&gt;57&lt;/sup&gt;Fe</td><td>Isoflex USA</td><td>iron-57</td><td>metallic form</td></tr><tr><td>standard eletrolytic Fe, 99.95 %</td><td>Sigma Aldrich (Merck)</td><td>1.03819</td><td>fine powder</td></tr><tr><td>electrolytic Co, 99.85 %</td><td>Sigma Aldrich (Merck)</td><td>1.12211</td><td>fine powder</td></tr><tr><td>electrolytic Cu, 99.8 %</td><td>Sigma Aldrich (Merck)</td><td>1.02703</td><td>fine powder</td></tr><tr><td>electrolytic Mo, 99.95 %</td><td>Sigma Aldrich (Merck)</td><td>1.12254</td><td>fine powder</td></tr><tr><td>crystalline B, 99.95 %</td><td>Sigma Aldrich (Merck)</td><td>266620</td><td>crystalline</td></tr><tr><td>calibration foil for M&amp;ouml;ssbauer spectrometry, bcc-Fe</td><td>GoodFellow</td><td>564-385-23</td><td>foil 0.0125 mm, purity 99.85 %</td></tr><tr><td>HNO&lt;sub&gt;3&lt;/sub&gt; acid, ANALPURE Ultra</td><td>Analytika Praha, Czech Republic</td><td>UAc0061a</td><td>concentration 67 %, volume 500 mL</td></tr><tr><td>spectrometer for atomic absorption spectrometry</td><td>Perkin Elmer 1100, Germany</td><td></td><td></td></tr><tr><td>spectrometer for optical emmission spectrometry with inductively coupled plasma</td><td>Jobin Yvon 70 Plus, France</td><td></td><td></td></tr><tr><td>X-ray diffractometer</td><td>Bruker D8 Advance, USA</td><td></td><td></td></tr><tr><td>differential scanning calorimeter</td><td>Perkin Elmer DSC 7, Germany</td><td></td><td></td></tr></tbody></table>

methods of ex situ and in situ investigations of structural transformations: the case of crystallization of metallic glasses

我们演示了采用两种基于核的分析方法, 可以遵循铁基金属玻璃的显微组织安排的修改。尽管它们的非晶性质, 超精细相互作用的识别揭示了微弱的结构修改。为此, 我们使用了两种技术, 利用核共振在稳定的57Fe 同位素的核水平, 即穆斯堡尔光谱和核前向散射 (NFS) 的同步辐射。利用原位试验和原位实验的结果, 讨论了热处理对 (Fe2.85Co1)77钼8铜1B14毫克的影响。由于这两种方法对超精细的相互作用都很敏感, 所以可以随时获得关于结构布置和磁性显微组织的信息。穆斯堡尔分光光度法对在一定条件下 (温度、时间) 退火后的室温下的结构布置和磁性显微结构的变化进行了描述, 从而使该技术检查稳定国家。另一方面, 在动态变化的温度和 nfs 检查瞬态状态时, 会在原位记录 nfs 数据。这两种技术的使用都提供了互补信息。一般情况下, 它们可以应用于任何合适的系统, 其中重要的是要知道它的稳定状态, 而且是瞬态状态。

图 2中的 XRD 模式呈现出广泛的无特征衍射峰。观察到的反射表明, 所生产的带状 (Fe2.85Co1)77钼8铜1B14毫克是 XRD 无定形。
由于其灵敏度, XRD 在揭示表面结晶方面有一定的局限性。晶粒的存在不到2-3% 的毫克是不重要的。因此, 有时使用 "XRD 非晶" 一词。
<p ...

Watch this Scientific Journal Video about Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses at JoVE.com

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

在这里, 我们提出了一个协议, 以描述原位和原位调查的结构转换在金属玻璃。我们采用了以核为基础的分析方法来检查超精细的相互作用。在温度驱动实验中, 我们证明了穆斯堡尔光谱和同步辐射核前向散射的适用性。

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic ...

methods-ex-situ-situ-investigations-structural-transformations-case

Research

JoVE Journal

Engineering

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

8.5K 次观看.  Slovak University of Technology in Bratislava, Slovakia. 在这里, 我们提出了一个协议, 以描述原位和原位调查的结构转换在金属玻璃。我们采用了以核为基础的分析方法来检查超精细的相互作用。在温度驱动实验中, 我们证明了穆斯堡尔光谱和同步辐射核前向散射的适用性。

视频: Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Simulation of the Planetary Interior Differentiation Processes in the Laboratory

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to that layered structure, (1) percolation of liquid metal in a solid silicate matrix by planet differentiation, and (2) inner core crystallization by subsequent planet cooling. We conduct high-pressure and high-temperature experiments to simulate both processes in the laboratory. Formation of percolative planetary core depends on the efficiency of melt percolation, which is controlled by the dihedral (wetting) angle. The percolation simulation includes heating the sample at high pressure to a target temperature at which iron-sulfur alloy is molten while the silicate remains solid, and then determining the true dihedral angle to evaluate the style of liquid migration in a crystalline matrix by 3D visualization. The 3D volume rendering is achieved by slicing the recovered sample with a focused ion beam (FIB) and taking SEM image of each slice with a FIB/SEM crossbeam instrument. The second set of experiments is designed to understand the inner core crystallization and element distribution between the liquid outer core and solid inner core by determining the melting temperature and element partitioning at high pressure. The melting experiments are conducted in the multi-anvil apparatus up to 27 GPa and extended to higher pressure in the diamond-anvil cell with laser-heating. We have developed techniques to recover small heated samples by precision FIB milling and obtain high-resolution images of the laser-heated spot that show melting texture at high pressure. By analyzing the chemical compositions of the coexisting liquid and solid phases, we precisely determine the liquidus curve, providing necessary data to understand the inner core crystallization process.

The high-pressure and high-temperature experiments described here mimic planet interior differentiation processes. The processes are visualized and better understood by high-resolution 3D imaging and quantitative chemical analysis.

模拟行星内部分化过程中的实验室

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to ...

科研

工程学

Production of Synthetic Nuclear Melt Glass

Realistic surrogate nuclear debris is needed within the nuclear forensics community to test and validate post-detonation analysis techniques. Here we outline a novel process for producing bulk surface debris using a high temperature furnace. The material developed in this study is physically and chemically similar to trinitite (the melt glass produced by the first nuclear test). This synthetic nuclear melt glass is assumed to be similar to the vitrified material produced near the epicenter (ground zero) of any surface nuclear detonation in a desert environment. The process outlined here can be applied to produce other types of nuclear melt glass including that likely to be formed in an urban environment. This can be accomplished by simply modifying the precursor matrix to which this production process is applied. The melt glass produced in this study has been analyzed and compared to trinitite, revealing a comparable crystalline morphology, physical structure, void fraction, and chemical composition.

A protocol for the production of synthetic nuclear melt glass, similar to trinitite, is presented.

生产合成核熔化玻璃

Realistic surrogate nuclear debris is needed within the nuclear forensics community to test and validate post-detonation analysis techniques. Here we ...

X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects

The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder diffraction (XRPD) is presented in detail via two case studies.
The first material under investigation was sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(OH)2&#8729;4H2O (sample 1) which forms on soda glass/copper alloy composite historic objects (e.g., enamels) in museum collections, exposed to formaldehyde and formic acid emitted from wooden storage cabinets, adhesives, etc. This degradation phenomenon has recently been characterized as &#34;glass induced metal corrosion&#34;.
For the second case study, thecotrichite, Ca3(CH3COO)3Cl(NO3)2&#8729;6H2O (sample 2), was chosen, which is an efflorescent salt forming needlelike crystallites on tiles and limestone objects which are stored in wooden cabinets and display cases. In this case, the wood acts as source for acetic acid which reacts with soluble chloride and nitrate salts from the artifact or its environment.
The knowledge of the geometrical structure helps conservation science to better understand production and decay reactions and to allow for full quantitative analysis in the frequent case of mixtures.

Modern high resolution X-ray powder diffraction (XRPD) in the laboratory is used as an efficient tool to determine crystal structures of long-known corrosion products on historic objects.

X射线粉末衍射在保护科学:迈向文物艺术品腐蚀产物的常规晶体结构测定

The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder ...

化学

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

一种新的方法<em&gt;原位</em&gt;纳米级样品的机电表征

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

Optimized Sealing Process and Real-Time Monitoring of Glass-to-Metal Seal Structures

Residual stress is an essential factor to keeping the hermeticity and robustness of a glass-to-metal seal structure. The purpose of this report is to demonstrate a novel protocol to characterize and measure residual stress in a glass-to-metal seal structure without destroying the insulation and hermeticity of sealing materials. In this research, a femto-laser inscribed fiber Bragg grating sensor is used. The glass-to-metal seal structure that is measured consists of a metal shell, sealing glass, and Kovar conductor. To make the measurements worthwhile, the specific heat treatment of metal-to-glass seal (MTGS) structure is explored to obtain the model with best hermeticity. Then, the FBG sensor is embedded into the path of sealing glass and becomes well-fused with the glass as the temperature cools to RT. The Bragg wavelength of FBG shifts with the residual stress generated in sealing the glass. To calculate the residual stress, the relationship between Bragg wavelength shift and strain is applied, and the finite element method is also used to make the results reliable. The online monitoring experiments of residual stress in sealing glass are carried out at different loads, such as high temperature and high pressure, to broaden functions of this protocol in harsh environments.

Key procedures to optimize the sealing process and achieve real-time monitoring of the metal-to-glass seal (MTGS) structure are described in detail. The embedded fiber Bragg grating (FBG) sensor is designed to achieve online monitoring of temperature and high-level residual stress in the MTGS with simultaneous environmental pressure monitoring.

玻璃到金属密封结构的优化密封工艺和实时监控

Residual stress is an essential factor to keeping the hermeticity and robustness of a glass-to-metal seal structure. The purpose of this report is to ...

Sample Preparation and Experimental Design for In Situ Multi-Beam Transmission Electron Microscopy Irradiation Experiments

There is a need to understand materials exposed to overlapping extreme environments such as high temperature, radiation, or mechanical stress. When these stressors are combined there may be synergistic effects that enable unique microstructural evolution mechanisms to activate. Understanding of these mechanisms is necessary for the input and refinement of predictive models and critical for engineering of next generation materials. The basic physics and underlying mechanisms require advanced tools to be investigated. The in situ ion irradiation transmission electron microscope (I&#179;TEM) is designed to explore these principles.
To quantitatively probe the complex dynamic interactions in materials, careful preparation of samples and consideration of experimental design is required. Particular handling or preparation of samples can easily introduce damage or features that obfuscate the measurements. There is no one correct way to prepare a sample; however, many mistakes can be made. The most common errors and things to consider are highlighted within. The I&#179;TEM has many adjustable variables and a large potential experimental space, therefore it is best to design experiments with a specific scientific question or questions in mind.
Experiments have been performed on large number of sample geometries, material classes, and with many irradiation conditions. The following are a subset of examples that demonstrate unique in situ capabilities utilizing the I3TEM. Au nanoparticles prepared by drop casting have been used to investigate the effects of single ion strikes. Au thin films have been used in studies on the effects of multibeam irradiation on microstructure evolution. Zr films have been exposed to irradiation and mechanical tension to examine creep. Ag nanopillars were subjected to simultaneous high temperature, mechanical compression, and ion irradiation to study irradiation induced creep as well. These results impact fields including: structural materials, nuclear energy, energy storage, catalysis, and microelectronics in space environments.

<meta charset="utf8"></head><body>原位多光束透射电子显微镜辐照实验的样品制备和实验设计

Sample preparation techniques are outlined with specific considerations for in situ ion irradiation TEM experiments. Ion species, energy, and fluence are discussed with methods for how to select and compute them. Finally, procedures for conducting an experiment are described and accompanied by the representative results.

原位多光束透射电子显微镜辐照实验的样品制备和实验设计

There is a need to understand materials exposed to overlapping extreme environments such as high temperature, radiation, or mechanical stress. When these ...

Crystallization of Proteins on Chip by Microdialysis for In Situ X-ray Diffraction Studies

This protocol describes the manufacturing of reproducible and inexpensive microfluidic devices covering the whole pipeline for crystallizing proteins on-chip with the dialysis method and allowing in situ single-crystal or serial crystallography experiments at room temperature. The protocol details the fabrication process of the microchips, the manipulation of the on-chip crystallization experiments and the treatment of the in situ collected X-ray diffraction data for the structural elucidation of the protein sample. The main feature of this microfabrication procedure lies on the integration of a commercially available, semipermeable regenerated cellulose dialysis membrane in between two layers of the chip. The molecular weight cut-off of the embedded membrane varies depending on the molecular weight of the macromolecule and the precipitants. The device exploits the advantages of microfluidic technology, such as the use of minute volumes of samples (&#60;1 &#181;L) and fine tuning over transport phenomena. The chip coupled them with the dialysis method, providing precise and reversible control over the crystallization process and can be used for investigating phase diagrams of proteins at the microliter scale. The device is patterned using a photocurable thiolene-based resin with soft imprint lithography on an optically transparent polymeric substrate. Moreover, the background scattering of the materials composing the microchips and generating background noise was evaluated rendering the chip compatible for in situ X-ray diffraction experiments. Once protein crystals are grown on-chip up to an adequate size and population uniformity, the microchips can be directly mounted in front of the X-ray beam with the aid of a 3D printed holder. This approach addresses the challenges rising from the use of cryoprotectants and manual harvesting in conventional protein crystallography experiments through an easy and inexpensive manner. Complete X-ray diffraction data sets from multiple, isomorphous lysozyme crystals grown on-chip were collected at room temperature for structure determination.

Crystallization of Proteins on Chip by Microdialysis for In Situ X-ray Diffraction Studies

This paper details the fabrication protocol of microfluidic chips developed for on-chip protein crystallization with the dialysis method and in situ X-ray diffraction experiments. The microfabrication process makes it possible to integrate a semipermeable regenerated cellulose dialysis membrane with any molecular weight cut-off, between two layers of the chip.

通过微透析对芯片上的蛋白质进行结晶，用于 原位 X射线衍射研究

This protocol describes the manufacturing of reproducible and inexpensive microfluidic devices covering the whole pipeline for crystallizing proteins ...

<meta charset="utf8"></head><body>利用机械化学方法合成高 ZT 热电材料

Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics

Mechanochemical synthesis is an extremely useful strategy to reach thermoelectric materials due to its solvent-free one-step character, as the targeted thermoelectricity (TE) materials in a nanocrystalline format can be prepared by mere high-energy milling of elemental precursors. Nevertheless, the subsequent densification method (e.g., spark plasma sintering or hot pressing) is required afterward, similarly to other synthetic methodologies. In this study, the simplicity of mechanochemical synthesis is&#160;presented for two selected metal chalcogenides, namely copper sulfide (Cu1.8S, digenite) and tin selenide (SnSe, svetlanaite), which are known for high ZT values. These compounds can be prepared via a mechanically induced self-propagating reaction (MSR), which is a combustion-like process instantly yielding the products in a very short timeframe (within 1 min). The occurrence of MSR can be well-tracked by in situ temperature monitoring since an abrupt temperature increase occurs at the moment of MSR. We have developed a device which is capable of monitoring the temperature inside the milling jar every 80 ms during planetary ball milling, and it is therefore possible to very precisely track the moment of MSR ignition. The developed device presents an improvement in the monitoring capabilities in comparison with commercially available analogs. This contribution aims to provide a visual insight into all steps, with simple high-energy ball milling of elements to reach TE materials and in situ temperature monitoring being the central points.

<meta charset="utf8"></head><body>展示了适用于热电的金属硫属化物的机械化学合成的简单性和原位温度监测

Here, we present a protocol to synthesize two metal chalcogenides (Cu1.8S and SnSe) suitable for thermoelectrics via an ultrafast (second-range), solvent-free, and one-step mechanochemical synthesis using elemental precursors. Simultaneously, we demonstrate the monitoring of the temperature in the jar during planetary ball milling in situ by the newly developed device.

展示了适用于热电的金属硫属化物的机械化学合成的简单性和原位温度监测

Mechanochemical synthesis is an extremely useful strategy to reach thermoelectric materials due to its solvent-free one-step character, as the targeted ...

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

摘要

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模拟行星内部分化过程中的实验室

生产合成核熔化玻璃

X射线粉末衍射在保护科学:迈向文物艺术品腐蚀产物的常规晶体结构测定

一种新的方法

玻璃到金属密封结构的优化密封工艺和实时监控

原位多光束透射电子显微镜辐照实验的样品制备和实验设计

原位多光束透射电子显微镜辐照实验的样品制备和实验设计

通过微透析对芯片上的蛋白质进行结晶，用于原位 X射线衍射研究

展示了适用于热电的金属硫属化物的机械化学合成的简单性和原位温度监测

展示了适用于热电的金属硫属化物的机械化学合成的简单性和原位温度监测

结构转换的原位和原位研究方法: 金属玻璃结晶的实例

摘要

探索更多视频

模拟行星内部分化过程中的实验室

生产合成核熔化玻璃

X射线粉末衍射在保护科学:迈向文物艺术品腐蚀产物的常规晶体结构测定

一种新的方法

玻璃到金属密封结构的优化密封工艺和实时监控

原位多光束透射电子显微镜辐照实验的样品制备和实验设计

原位多光束透射电子显微镜辐照实验的样品制备和实验设计

通过微透析对芯片上的蛋白质进行结晶，用于 原位 X射线衍射研究

展示了适用于热电的金属硫属化物的机械化学合成的简单性和原位温度监测

展示了适用于热电的金属硫属化物的机械化学合成的简单性和原位温度监测

通过微透析对芯片上的蛋白质进行结晶，用于原位 X射线衍射研究