这项工作得到了美国能源部, 核能的核能大学项目 (奖 No。DE-NE0008425);综合大学项目研究生奖学金 (No. 奖DE-NE0000113);以及贸易、工业和 #38 部; 能源、大韩民国、能源效率和 #38; 韩国能源技术评价和规划研究所资源核心技术方案 (KETEP) (No. 20142020104190)。这篇文章的出版部分由宾夕法尼亚州立大学图书馆开放获取出版基金资助。

1. 电化学电池组件的制作 <ol> <li> 制作二进制咖啡馆 2 AF 2 电解质 <ol> <li> 计算二进制的每个组件所需的质量电解质为350.0 和 #177; 5.0 克混合物与97摩尔 CaF 2 和3摩尔 AF 2 ( 例如, 333.4 g 的 caf 2 和 16.6 g 的战略成果 2 ). </li>
		<li> 测量并将盐混合物倒入1.5 升塑料瓶, 以及大约1.3 公斤钇稳定氧化锆研磨介质 (3 mm 直径) 和25.0 和 #177; 0.1 克聚乙烯醇 (PVA、有机粘合剂)。然后加入异丙醇 (国际音标), 直到瓶子4/5 满。关闭瓶子, 并手动摇动其内容约1分钟, 以均匀地分配混合物的组成部分. </li>
		<li> 把塑料瓶与盐混合物放在球磨机上 (两个滚筒, 12.5 和 #34; 长度)。设置球磨机的速度为每分钟250转 (RPM) 和24小时的轧机. </li>
		<li> 将混合物通过筛子 (10 目) 倒入平底锅中, 将研磨介质和盐混合物分开。使用挤压瓶, 轻轻冲洗筛与10毫升的国际音标, 以捕捉其余的混合物. </li>
		<li> 将球磨均匀的混合物在通风罩中晾干24小时, 然后用砂浆和杵将混合物研磨成细粉. 
		注意: 如果需要加速干燥过程, 可将平底锅放在热板上设置为 373 K. </li>
		<li> 测量出130.0 和 #177; 1.0 克电解质粉末, 并将粉末均匀地装入颗粒状模具 (75 毫米直径, 60 mm 高度). </li>
		<li> 使用压模机, 单按30兆帕斯卡压力2分钟的粉末, 形成一个直径为75毫米的绿色颗粒和17毫米的厚度。为了从颗粒模中除去颗粒, 倒置颗粒模, 放置一个不锈钢环 (外径101毫米, 直径35毫米, 厚度为4.8 毫米), 以球团为中心的颗粒模的顶部为中心。小心地按下1.0 压杆的颗粒模冲, 从模具中取出颗粒. </li>
		<li> 使用小钻头 (1 mm 直径) 在绿色颗粒中创建攻丝孔 (深度为0.5 毫米), 其中一个位于中心, 六均匀间隔 25.4 mm 在钻具中心之间。然后使用大钻头 (11.2 毫米直径) 手动钻七口井为中心的攻牙孔, 每一个约12毫米深 (约和 #190; 通过颗粒的方式). </li>
		<li> 所需的六电解质帽的每一个, 测量出4.5 和 #177; 0.5 克电解质粉末, 并将粉末均匀地装入颗粒状模具 (19 毫米直径, 50 mm 高度). </li>
		<li> 单将7.5 兆帕斯卡的电解质粉末压入一个绿色颗粒19毫米 #215; 10 毫米直径和厚度。要从颗粒模中取出颗粒, 倒置颗粒模, 放置一个不锈钢环 (37.5 毫米外径, 30 毫米高度, 3.5 毫米厚度), 以球团为中心的颗粒模的顶部为中心。小心地按下1.0 压杆的颗粒模冲, 从模具中取出颗粒。使用一个小钻头 (2 毫米直径), 以手动钻一个中心孔通过每个盖帽. 
		注: 来自1.1.8 的绿色颗粒。和1.1.10。可以在以下步骤中烧结形成单相固体电解质. </li>
		<li> 对于每个大型电解质颗粒和一套六小电解质帽, 用粗氧化铝粉末轻轻覆盖氧化铝板 (10 厘米直径, 4.65 毫米厚), 以促进烧结颗粒从氧化铝板中分离。将电解质件放在氧化铝粉末上, 这样它们就不会相互接触. </li>
		<li> 将上述组件从1.1.11 置于高温箱式炉中。烧结件与以下加热剖面: 393 k 为12小时去除湿气, 823 k 为 12 h 烧出 PVA, 并且 1273 k 为 3 h 到烧结, 所有以热化率 5 k/分钟。然后冷却到 298 k 的速度为2.5 克/分钟. </li>
	</ol> </li> <li> 在氩气填充的手套中制作碱土金属电极 <ol> <li>, 测量二元合金的两个分量的质量, 其组合质量至少为6.0 克 (如 、5.6 克和0.4 克 Ba钡摩尔分数的 Ba-铋合金 x Ba = 0.10)。放置在托盘中, 并从手套中移除. 
		注: 活性金属储存在矿物油下以防止氧化。为了除去矿物油, 几种十年代在丙酮中的碱土金属金属件. </li>
		<li> 将所有金属件放在弧熔舞台的中心, 确保舞台的安全. </li>
		<li> 将真空吸在燃烧室上3分钟, 直到达到大约-1.0 bar (压力) 的真空, 然后用氩气填充到 0.0 bar (压力计)。重复此步骤至少三次, 以确保电弧熔化过程中的惰性氩气. </li>
		<li> 关闭熔装置上的护眼保护罩, 打开电流, 在熔的舞台和钨尖端之间创建一个稳定的电弧。将金属片熔化成一个单一的均匀的工件, 将工件暴露在电弧中。在合金件中没有可观察到的分离相, 就可以证实充分的熔化. 
		注: 如果高活性元素被熔化, 使用高电流大于 ~ 5 s 会导致材料汽化, 并导致合金成分的不一致. </li>
		<li> 将工件熔化成单个合金后, 关闭电流和电弧熔。从腔室中拧开舞台, 翻转合金, 然后将舞台螺钉回弧熔室。重复 1.2.3-1.2.5 三次, 形成一个均匀的合金. </li>
		<li> 在熔合金后, 再次从腔室中拧开舞台, 并将合金分解或切割成大约3到6小块。将棋子放在舞台上, 然后将舞台螺钉放回弧熔室。根据步骤 1.2.3-1.2.5, 将碎片重新熔化成一个单片. </li>
		<li> 允许系统冷却 3-5 分钟, 将舞台从电弧熔系统中分离出来, 并将合金存储在塑料袋中。将包置于惰性氩气气氛下 ( 例如 , 手套), 直到最终的电化学电池组件. 
		注: 对于每个实验, 将需要两个参考电极合金件和多达四工作电极合金件的不同组成. </li>
	</ol> </li> <li> 准备钨电气引线和热电偶 <ol> <li> 切割6根钨丝 (1 mm 直径) 46 厘米长。手工砂沿每条导线的长度, 以消除表面污染物, 如氧化层, 使用100砂砾砂纸。使用丙酮湿巾清洗钢丝表面. </li>
		<li> 在电化学测量过程中, 将导线插入铝管 (直径为6.35 毫米, 长度为30.5 厘米), 以防止电引线和不锈钢试验室之间的电短路。在一端 (底部) 留下大约12.7 厘米作为酒吧e 线与电极接触, 另一端为2.5 厘米 (顶部), 用于与电位引线的电接触. </li>
		<li> 将大约3克的快速固化环氧树脂和硬化剂混合在一起, 使用木材涂抹棒的末端1分钟. </li>
		<li> 用导线在管子, 应用大约 3 g 环氧树脂到管子的顶端封印它。使用实验室支架垂直放置管和导线, 并允许环氧树脂固化15分钟. 重复每根钨丝 (电铅). </li>
		<li> 将 45 cm 热电偶 (K 型) 的底部插入一个新的30.5 厘米长的氧化铝管的顶部, 并密封热电偶与氧化铝管之间的间隙, 使用快速固化环氧树脂类似于步 1.3.4, 留下〜 5 mm 的热电偶暴露在顶部。允许环氧树脂固化15分钟. </li>
	</ol> </li> </ol> 2。电化学电池的组装 <ol> <li> 在电化学电池组件前清洗, 在电化学电池的组装之前, 将不锈钢试验室的内表面彻底砂100砂砾砂纸, 直到在不锈钢表面没有明显的污染。使用去水清洗测试室、室盖和氧化铝坩埚 (8.2 厘米直径、3.0 厘米高) 并用国际音标冲洗. </li>
		<li> 几种的真空配件和 o 形环的异丙醇的部分为〜10分钟, 并允许他们在干燥烤箱内干燥 373 k. 在 o 型环上涂上一层真空润滑脂, 以改善真空质量。然后将所有的电化学设置元件移动到一个氩气填充手套中进行组装. </li>
	</ol> </li> <li> 加载电化学电池组件 <ol> <li> 将烧结电解质 (步骤 1.1) 置于位于测试室托架中的氧化铝坩埚的中心. </li>
		<li> 将足够的电极材料装入每个井中, 使材料的顶部与电解质的表面齐平。用参考电极材料填充两个井 ( 例如 , ba-铋 ( x ba = 0.05)) 相同的成分。然后用工作电极材料填充四口井, 每个孔都有不同的组成 ( 图 2 )。在这一步, 形状电弧熔化电极材料接近的电解质井的圆柱形, 并钻一个中心通过孔 (2 毫米直径) 的电气引线插入使用加工工具 ( 如 , mini-lathe, 钻头, 等 ). 
		注: 尽量减少样品在空气中的曝光时间, 以减少氧化。广泛的氧化表明, 存在一个 non-lustrous (钝) 表面层的样品。要除去氧化层, 用100粒砂纸打磨样品表面, 用干擦干净. </li>
		<li> 插入电引线组件 (1.3 中的氧化铝管的钨丝), 通过室盖的真空管接头端口、腔板的挡板、电解质帽上的孔以及合金电极的孔。对所有六电极重复此步骤。然后插入热电偶通过最后一个真空管接头口岸和入第七井在中心。用合金牢固地接触电解质表面。完整的程序集显示在 图 2 和 图 3 中。
		注: 每根钨丝必须牢牢地接触电解质表面。如果合金太脆而无法加工, 可以通过压紧对合金的导线, 并通过在真空管接头端口上收紧真空装置来固定其位置, 从而将钨丝压制在合金上. </li>
		<li> 将大 o-ring 置于不锈钢真空室顶部的凹槽中。将所组装的电化学电池小心地降低到试验室。安全地拧紧所有真空密封元件和测试室的夹具. </li>
	</ol> </li> <li> 从电磁场测量的电化学电池组件中除去湿气和氧气 <ol> <li> 将组装的测试室加载到坩埚熔炉中。在真空室的外露表面周围放置两层玻璃纤维绝缘, 以确保电化学电池中的温度分布均匀, 防止在测试顶部出现环氧密封失效。会议厅. </li>
		<li> 将冷却水线连接到测试室的冷却管入口和出口端口 ( 图 3 和 图 4 )。
		<li> 将真空/氩线连接到测试室的入口口, 并关闭出口端口阀门。疏散测试室, 直到真空计读数低于 10 mtorr. 
		注: 如果真空度达不到 10 mtorr, 请检查测试室的密封件, 包括 o 形环、夹具、管件和环氧密封件. </li>
		<li> 在主动真空 (和 #60; 10 mtorr) 下, 将加热炉的温度提高到 373 k/分钟, 并保持为 10 h; 在相同的升温速率下增加到 543 k, 并保持 10 h. 注意: 干燥过程需要约 20 h. </li>
		<li> 上述干燥程序完成后, 用超高纯度氩气清洗腔室。重复疏散 (#60; 10 mtorr) 和氩气清除 (1 atm) 至少三次, 以确保在高温下运行的惰性气氛. </li>
		<li> 在最后一次氩气清除后, 打开测试室的入口和出口阀门, 并调整流量计以保持50.0 毫升/分钟在环境常压室压力 (约 1 atm) 上的连续氩气流量. </li>
	</ol> </li> </ol> 3。电化学测量 <ol> <li> 建立单元组件和电位之间的电接点 <ol> <li> 将计数器电极电缆和参考电极电缆从电位连接起来, 一旦熔炉达到 543 K. 
		注: 每根电极电缆 ( 例如, 参考电极、计数器电极、工作电极、传感电极电缆) 在电缆的末端都有一个插头, 允许电连接. </li>
		<li> 将鳄鱼夹子从电位的参考电极电缆的末端连接起来, 并将其从单元格组件中夹入参考电极的电气引线中. </li>
		<li> 在多路复用 (MUX) 开关盒上插入五工作电极电缆, 一个插入每个端口1到5。将鳄鱼夹子固定在每个工作电极电缆上, 并将每条鳄鱼夹子连接到电化学电池组件中的每个工作电极的电子引线, 从而使其他五电极的顺序电压测量相对到参考电极. 
		注: 一个工作电极应具有与参考电极相同的成分。这两个相同的电极之间的电压差应约为零, 并应在整个测量过程中进行监测。电压差小于 2-3 mV 表明的稳定性和可靠性的参考电极系统的准确电磁场测量. </li>
		<li> 将接地电缆的一端连接到不锈钢测试室并插入另一端方向蚊进入电源插座的接地口. 
		注: 本程序有效地抑制了来自炉膛发热元件的电噪声, 因为在电化学测量过程中, 不锈钢试验室充当法拉笼. </li>
		<li> 使用电化学软件创建程序, 使用电位软件在恒模式下依次测量每个工作电极的开路电位 (泛型). 
		注: 自定义程序, 可根据要求, 测量和记录每个工作电极的泛消费, 依次通过每个工作电极, 随着时间的推移, 每次轮换持续15分钟。该程序应旋转通过一套工作电极, 以记录在每一个温度增量的消费测量. </li>
		<li> 将熔炉温度从 543 k 增加到 1073 k, 在 5.0 k/分钟, 电解质成为离子导电的电磁场测量. 
		注: 在 1073 K, 参考电极应充分熔融, 以建立稳定的电接触电解质和电铅, 提高稳定性的参考电极电位在电动势测量. </li>
	</ol> </li> <li> 在 emf 测量期间设置热循环加热炉的热剖面 注: 温度范围取决于电极组合物的相变行为 (如 、熔化温度) 以及合金成分的反应性。下面给出了723和 1073 K 之间的钡铋和锶铋合金系统的典型温度分布。
	<ol> <li> 程序将炉膛控制器的温度从 1073 k 降低到 723 k, 并从 723 k 到 1073 k, 在 25 k 间隔内以递增速率 #177; 5 k/分。在每一个温度步骤 (每 25 K 间隔), 保持温度为 1-2 小时, 使元件达到热量和电化学平衡. 
		注: 当电池温度保持在和 #177 内时, 热量平衡达到了; 1 K 在每个温度步由伴生的数据采集 (数据采集) 系统显示的热电偶数据表示. </li>
	</ol> </li> <li> 温度和 emf 数据收集 <ol> <li> 使用热电偶数据采集系统在整个热循环期间记录电化学电池的温度; 包括炉子的上、下温度极限程序和热电偶的类型。在温度记录的同时启动 emf 测量程序. 
		注: 每个工作电极的测量都是参照电极测量的。两个参考电极之间的测量值应小于2-3 毫伏. </li>
		<li> 使用电池温度和每个工作电极的泛型测量来确定每个碱土金属-液态金属合金作为温度函数的电磁场值。每个温度下的泛消费值是工作和参考电极之间的电磁场值. </li>
	</ol>
	</li>
</ol>

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<li>Smith, N. D., Lichtenstein, T., Gesualdi, J., Kumar, K., Kim, H. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S001346861632597X">Thermodynamic Properties of Strontium-Bismuth Alloys Determined by Electromotive Force Measurements.</a> Electrochim. Acta. 225, 584-591 (2017).</li>
<li>Kim, H., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S001346861101694X">Thermodynamic properties of Calcium-Bismuth alloys determined by emf measurements.</a> Electrochim. Acta. 60, 154-162 (2012).</li>
<li>Okamoto, H. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aOkamoto%2C+H+%22Ba-Bi+%28Barium-Bismuth%29%22">Ba-Bi (Barium-Bismuth)</a>. , 2nd ed, ASM International, Materials Park. (1990).</li>
<li>Lichtenstein, T., Gesualdi, J., Nigl, T. P., Yu, C. T., Kim, H. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0013468617315311">Thermodynamic Properties of Barium-Antimony Alloys Determined by Emf Measurements.</a> Electrochim. Acta. , (2017).</li>
<li>Wagner, C. <a target="_blank" href="http://jes.ecsdl.org/content/115/9/933.short">Limitation of the Use of CaF2 in Galvanic Cells for Thermodynamic Measurements due to the Onset of Electronic Conduction under Reducing Conditions.</a> J. Electrochem. Soc. 115 (9), 933-935 (1968).</li>
</ol>

作者没有利益冲突透露关于出版物的材料。

这项工作中的 emf 电池使用的是基于 CaF2的固体电解质和固定成分的电极材料, 与使用库仑滴定技术的 emf 电池相比, 在恒定温度下改变电极成分。采用库仑滴定法, 由法拉第定律确定电极的组成, 假设库仑效率良好。然而, 高活性碱土金属是适度可溶性的 (例如, Ba ~ 15 摩尔可溶性在氯化2) 在他们自己的卤化物盐, 能促进电子传导通过电解质和防止准确控制库仑滴定过程中电极的组成7,13。本工作中的电化学电池以固定成分的电极材料为原料, 通过库仑滴定法消除了成分核算的不确定性, 从而实现了对碱土金属合金的精确电磁场测量。此外, 这项工作中独特的电化学细胞在同一实验中同时测量了四合金组合物的 emf 值, 以加速对各种组合物的热力学性质的评价, 并温度.
由于电弧熔用于制造二元合金, 因此, 由于电弧的高温和金属的高蒸气压, 合金的最终成分可能会偏离初始成分。为了准确地报告二元合金的电磁场温度关系, 用电感耦合等离子体原子发射光谱 (icp-aes) 对它们的组成进行了确认, 如表 3中所示的 Ba Sb 系统12。
在按步2.3.4 烘干电化学电池元件之前, 可能会出现高品质真空 (和 #60; 10 mtorr) 的困难。真空室设置中的 o-ring 在其不锈钢槽中可能无法正确就位。在氧化铝管的环氧密封上也可能存在缺口, 可以采用附加的环氧树脂来堵塞可能的泄漏。在电磁场测量中 , 如果电气引线失去与 B 合金的接触 , 并观察到 emf 值的动 , 则可以通过轻轻地将氧化铝管扭曲来重新与合金进行接触 , 从而使液态合金润湿铅。
偶尔地电磁场价值可能陈列大滞后在冷却和热化周期之间。一般而言, 冷却/加热循环之间的电磁场值的滞后可能来源于 (1) 电解质与反应电极组合物的降解, 特别是在高碱-土浓度下;(2) 高温汽化时电极材料的降解和试验室内残余氧的氧化;或 (3) 电极材料的非平衡相行为, 包括过冷效应和冷却周期中亚稳态相的形成。
当电极与电解质之间的降解反应明显时, 可以通过降低最大工作温度来改进实验装置, 以减少电化学电池的降解。在存在过冷效应的情况下, 在加热循环中获得的电势值可用于确定平衡热力学性质。当亚稳态相的形成引起电磁场测量的滞后时, 电极材料的相行为需要通过互补技术进行检查,例如, 通过 XRD 进行结构表征, 相位成分分析通过扫描电子显微镜 (SEM) 和能量色散谱 (EDS) 和相变温度的 DSC。相变数据也可能难以获得所描述的 emf 测量技术超过 1223 K, 因为 CaF2-AF2电解质可能开始下降。
这项工作中的电动势测量技术可用于确定二元碱性土-液态金属合金的经验热力学性质, 包括活性、部分摩尔熵、部分摩尔焓和相变温度。这些热力学数据被用来作为实验基础, 以补充技术 (XRD、DSC 和 SEM) 来精炼碱土金属的二元相图, 如图 85所示。根据液态金属 (B = 铋和锑) 中每种碱土金属 (A = Ca、Ba 和 Sr) 的活动值, 可以利用碱土金属和液态金属之间的原子相互作用的强度来电化学分离出碱性地球从熔盐溶液中裂变产物。

电动势 (emf) 测量可以直接确定化学反应的部分摩尔自由能变化, 并提供准确的热力学性质, 如活动, 部分摩尔焓, 和部分摩尔熵1。热化学数据的获取对于材料界的各种研究课题是至关重要的, 从多组分相图的提炼, 到对第一原理材料建模的实验验证, 到新的合成具有优越性质的金属间化合物种类。最近, Kim et al.利用 emf 测量来评估使用液态金属电极将碱性地球物种从熔融盐电解质中分离出来的可行性,2。
电化学分离使用熔融盐 (例如, 氯化-氯化钾) 是一种很有前途的技术分离铀和铀金属从使用的核燃料回收的3。由于用过的燃料在熔融盐中作为阳极处理, 所以标准还原电位低于铀的裂变产物被氧化并在熔融盐中积聚为溶解离子 (如 Ba2 +、Sr2 +、Cs+和 rare-earth金属阳离子)4。因此, 熔化的盐电解质必须周期性地被替换并且/或者进一步处理分离被积累的裂变产品4。特别令人关注的是碱/碱土金属裂变产物 (Ba2 +、Sr2 +和 Cs+), 因为这些离子在组成阳离子中表现出最低的标准还原电位, 使它们难以分离从熔盐溶液。
但是, 列支敦士登的et al.最近表明, 钡在液态铋中表现出低的热力学活性 (8.7 x 10-12在钡痣分数xBa (在 Bi 中) = 0.05, 1123 K), 这意味着强原子钡与铋的相互作用5。Kim et al.观察到, 这些相互作用导致钡离子的沉积电位转变为液态铋电极 (-3.74 v 到-2.49 v vs. cl/cl2(g)), 从而使钡的优先沉积从电解质溶液 (氯化2-氯化-CaCl2-氯化钠, 16-29-35-20 摩尔) at 773-973 K6。利用液态金属电极选择性地将碱/碱土金属裂变产物从用于电化学处理核燃料的电解质中分离出来, 可以使沉积电位的这种转变发挥杠杆作用。为了确定从熔融盐电解质中分离碱/碱-土裂变产物的可行性, 必须确定这些元素在未来液态金属 (如、铋、锑) 中的热力学性质。
在先前的研究中, Delcet et al.利用库仑滴定法来确定二元合金的热力学性质 (如: 如、ba、ba、ba-Pb)7。对于 Ba-铋合金, 直到xBa = 0.50, 他们采用了库仑滴定法, 使用单晶曝气生物滤池2电解质在 1123 K, 并观察了铋中钡的可比活性值 (2.4 x 10-12在xBa (在 Bi 中) = 0.05, 1123 K)。但据报道, 由于二元合金中钡含量的不确定性, 结果不准确。钡金属是高活性的, 可溶于其卤化物盐 (〜15摩尔在氯化2在 1163 K), 这可能导致更高的温度下卤化物盐的电子传导和导致不准确的成分会计在库仑滴定.为了确定含有高活性元素的二元合金的热力学性质 (例如、多余部分摩尔自由能、部分摩尔焓、部分摩尔熵), 使用了本协议中描述的 emf 方法。
二元合金的热化学性质可以通过测量合金 (a-b) 的平衡单元电位E细胞(即, emf) 来确定, 相对于纯金属 a 的参考电位。然后, 根据能关系 (), 细胞电位与细胞反应的部分摩尔自由能 (或化学势) 的变化直接相关.<img alt="Equation 1" src="/files/ftp_upload/56718/56718eq1.jpg">
对于在这项工作中的碱土金属电磁场测量, 氟离子导电 CaF2被选为基电解质, 因为 ca2 +/ca 氧化还原电位 (E0 =-5.59 V) 比其他在氟化物系统<img alt="Equation 2" src="/files/ftp_upload/56718/56718eq2.jpg"> </img>8中, 碱性地球氧化还原电位(例如,, vs f/f <img alt="Equation 2" src="/files/ftp_upload/56718/56718eq2.jpg"> 2(g) at 873 K)。这意味着, CaF2比其他碱性地球氟化物 AF2 (A = Sr 或 Ba) 更具化学稳定性, 并且那 Ba2 +或 Sr2 +离子是活性种类在 CaF2-曝气生物滤池2和 CaF2-战略成果框架2电解质, 分别。利用高稳定性的 caf2, 它最大限度地减少了与 Ba 或 Sr 合金的副反应, 以及 caf2在高温下的离子电导率, 单相二进制咖啡馆2AF2电解质成功地用来精确测量二元碱土金属金属合金的电势。在图 19中, 通过 x 射线衍射 (XRD) 分析确认了单相二元电解质的形成。
为了测量碱性地合金的细胞电位, 以下电化学电池是使用 solid-state 二进制咖啡馆2-AF2 (97 摩尔 caf2, 3 摩尔 AF2) 电解质10:
<img alt="Equation 4" src="/files/ftp_upload/56718/56718eq4.jpg">,
其中纯碱土金属 a (a = Ca, Sr 或 Ba) 充当参考电极 (RE), 固态 CaF2-AF2作为电解质, 固定成分 a-b 合金作为工作电极 (我们), b 是候选液态金属, 如 Bi 或 Sb。半反应在电化学细胞是: 
<img alt="Equation 5" src="/files/ftp_upload/56718/56718eq5.jpg"> 
<img alt="Equation 6" src="/files/ftp_upload/56718/56718eq6.jpg">
整个细胞反应是: 
<img alt="Equation 7" src="/files/ftp_upload/56718/56718eq7.jpg">
其中 e-是在单元反应中交换的电子, 而z是交换的电子的数量 (z = 2 用于碱性地球元素)。对于这个整体的反应, 在一个金属, 的部分摩尔自由能的变化是通过以下方法给出的: <img alt="Equation 8" src="/files/ftp_upload/56718/56718eq8.jpg"> </img> 
<img alt="Equation 9" src="/files/ftp_upload/56718/56718eq9.jpg"> 在<img alt="Equation 10" src="/files alt="Equation 10" src=""></img alt="Equation 10" src="/files>/ftp_upload/56718/56718eq10. jpg "/>> 是部分摩尔吉布斯自由能金属在金属 B, 是标准的吉布斯自由能纯金属, <img alt="Equation 11" src="/files/ftp_upload/56718/56718eq11.jpg"> R是理想的气体常数, T是温度在开尔文, 和a是金属 B 中 A 的活动。被测量的细胞电动势, E细胞, 是直接地与部分磨牙吉布斯自由能的变化能等式, 
<img alt="Equation 12" src="/files/ftp_upload/56718/56718eq12.jpg"> 其中, F是法拉第常量。

<table><tbody><tr><td>1 L bottle</td><td>US Plastic</td><td>69032</td><td>HDPE, wide mouth</td></tr><tr><td>Acetone, 99.5%</td><td>Alfa Aesar</td><td>30698</td><td>ACS Grade</td></tr><tr><td>Alumina dish</td><td>AdValue Technology</td><td>AL-4120</td><td>81 mm OD, 30 mm height</td></tr><tr><td>Alumina plate</td><td>AdValue Technology</td><td>AL-D-82-6</td><td>10 cm in diameter, 4.65 mm thickness</td></tr><tr><td>Alumina powder</td><td>AluChem</td><td></td><td>AC99 tabular alumina</td></tr><tr><td>Alumina tube</td><td>Coorstek</td><td>66631-12.0000</td><td>0.25 in. OD, 12 in. length</td></tr><tr><td>Arc-Melter</td><td>Edmund Buhler GmbH</td><td>MAM1</td><td></td></tr><tr><td>Argon, 99.999%</td><td>Praxair</td><td>AR 5.0UH-K</td><td>Ultrahigh purity</td></tr><tr><td>Ball mill</td><td>Norton Chemical Process Products Corporation</td><td>CF-70109</td><td>6 sets of 2 12.5 in. rollers, RPM 1725/1425</td></tr><tr><td>Barium</td><td>Alfa Aesar</td><td>653</td><td>99.2% purity</td></tr><tr><td>Barium fluoride</td><td>Sigma-Aldrich</td><td>652458</td><td>99.999% purity</td></tr><tr><td>Bismuth</td><td>Sigma-Aldrich</td><td>556130</td><td>99.999% purity</td></tr><tr><td>Boron nitride</td><td>Saint-Gobain</td><td>AX-05</td><td></td></tr><tr><td>Calcium fluoride</td><td>Alfa Aesar</td><td>11055</td><td>99.95% purity</td></tr><tr><td>Cotton tip applicator</td><td>Dynarex</td><td>4301</td><td>100 count, 3 in. long</td></tr><tr><td>Die press</td><td>Carver, Inc.</td><td>3850</td><td>Clamping force: 12 tons; Platens: 6&amp;nbsp; x 6 in.</td></tr><tr><td>Drill bit 29 piece set</td><td>Chicago-Latrobe</td><td>45640</td><td>1/16 in. - 1/2 in. x 1/64 in.</td></tr><tr><td>Drying pan</td><td>Pyrex</td><td>5300114</td><td>15.5 in. x 9.5 in. x 2.25 in.</td></tr><tr><td>Emery paper</td><td>McMaster-Carr</td><td>4681A21&amp;nbsp;</td><td>Grit size: 100</td></tr><tr><td>Fiberglass insulation</td><td>McMaster-Carr</td><td>9346K38</td><td></td></tr><tr><td>Flowmeter</td><td>Brooks</td><td>MR3A00SVVT</td><td>Range: 0.1 to 1 standard cubic feet per hour (SCFH) of Air</td></tr><tr><td>Gas bubbler</td><td>Ace Glass</td><td>8761-10</td><td></td></tr><tr><td>High temperature box furnace</td><td>Thermolyne</td><td>F48020-80</td><td>48000 Furnace, 8-segment program, Max. 1,200 &amp;deg;C</td></tr><tr><td>High temperature crucible furnace</td><td>Mellen</td><td>CC12-6X12-1Z</td><td>6 in. ID, 12 in. depth. Max temp 1,200 &amp;deg;C. 208 V</td></tr><tr><td>High vacuum grease</td><td>Sigma-Aldrich</td><td>Z273554</td><td>Brand: Dow Corning</td></tr><tr><td>Inert atmopshere glovebox</td><td>Mbraun</td><td>MB200</td><td></td></tr><tr><td>Isopropyl alcohol</td><td>Macron Chemicals</td><td>3032-21</td><td>ACS Grade</td></tr><tr><td>Large pellet die set</td><td>MTI Corporation</td><td>EQ-Die-75D</td><td></td></tr><tr><td>Polyvinyl alcohol, 99+%</td><td>Sigma-Aldrich</td><td>341584-5KG</td><td>Hydrolyzed, molecular weight (MW): 89,000-98,000</td></tr><tr><td>Potentiostat</td><td>Autolab</td><td>PGSTAT302N</td><td></td></tr><tr><td>Potentiostat-multiplexing switch box</td><td>Autolab</td><td>MUX SCANNER16 F/16 X WE</td><td>Multiplexer (MUX) SCANNER16</td></tr><tr><td>Potentiostat control software</td><td>NOVA</td><td></td><td>NOVA 1.11</td></tr><tr><td>Precision mini lathe</td><td>Harbor Freight Tools</td><td>93212</td><td>Brand: Central Machinery&amp;nbsp;</td></tr><tr><td>Quick cure epoxy</td><td>Grainger</td><td>5A462</td><td>Brand: Devcon</td></tr><tr><td>Recirculating chiller</td><td>VWR International</td><td>13271-204</td><td>Model: 1175PD</td></tr><tr><td>Small pellet die set</td><td>MTI Corporation</td><td>EQ-Die-18D-B</td><td></td></tr><tr><td>Sonicator</td><td>VWR International</td><td>97043-968</td><td></td></tr><tr><td>Squeeze bottle</td><td>VWR International</td><td>16650-022</td><td>LDPE, 500 mL</td></tr><tr><td>Stainless steel mesh sieve</td><td>Amazon</td><td></td><td>10 mesh, 2 mm holes</td></tr><tr><td>Strontium</td><td>Sigma-Aldrich</td><td>343730</td><td>99% purity</td></tr><tr><td>Strontium fluoride</td><td>Sigma-Aldrich</td><td>450030</td><td>99.99% purity</td></tr><tr><td>Thermocouple</td><td>Omega</td><td>KMQXL-125U-18</td><td>K-type thermocouple</td></tr><tr><td>Thermocouple acquisiton board</td><td>National Instruments</td><td>NI-9211</td><td></td></tr><tr><td>Tungsten wire</td><td>ThermoShield</td><td>88007-0.100</td><td>99.95% wire</td></tr><tr><td>Vacuum pump</td><td>Pfeiffer</td><td>PK D56 707</td><td>Duo Line 1.6</td></tr><tr><td>Wipes</td><td>Kimtech</td><td>S-8115</td><td>ULine distributor</td></tr><tr><td>Wire cutters</td><td>McMaster-Carr</td><td>5372A4</td><td></td></tr><tr><td>Yttria-stabilized zirconia milling media</td><td>Tosoh, USA</td><td></td><td>3 mm diameter</td></tr></tbody></table>

determination of thermodynamic properties of alkaline earth-liquid metal alloys using the electromotive force technique

基于 CaF2 solid-state 电解质的新型电化学电池已开发出用于测量二元碱性地球液态金属合金的电动势 (emf) 作为成分和温度的函数, 以获得热力学数据。该细胞由一个化学稳定的 solid-state CaF2-AF2电解质 (其中 a 是碱性地球元素, 如 Ca, Sr, 或 Ba), 与二元 a b 合金 (那里 b 是液体金属例如 Bi 或 Sb) 工作电极和纯净金属参考电极。Emf 数据收集的温度范围 723 k 至 1123 k 25 k 增量为多个合金成分的每个实验, 并分析结果的产量活动值, 相变温度, 和部分摩尔熵/焓每个组合。

图 5显示在冷却和再加热电化学电池时所做的电磁场测量: ba 双 (xba = 0.05) |CaF2-曝气生物滤池2|ba 双 (xBa = 0.05、0.10 和 0.20), 其中 ba 铋合金在xba = 0.05 充当参考电极5。
在整个测量过程中, 两个相同的 Ba-铋合金在xba = 0.05 中的电位差仍小于2毫伏, 这表明了参考电极的稳定性和可靠性。对于在xBa = 0.10 和xba 0.20 中的合金成分, 在加热和冷却循环期间获得了一个对称的 emf 剖面, 在热循环期间指示可重现的 emf 值。在每个温度步 (每 25 K 间隔), 细胞温度和细胞电势值达到热和电化学稳态在少于 1-2 h (图 5)5。
为了确定 ba 铋合金在纯 ba (s) 标准状态下的热力学性质, ba 铋 (xBa = 0.05) 合金参考电极的电势值必须对纯 ba 进行校准。参考电极的电势值与纯 ba 有关, 使用单独的电化学电池来确定: ba (s) |CaF2-曝气生物滤池2|ba 双 (xBa = 0.05), 结果显示在图 6中。使用此测量的线性拟合在xba = 0.05 (图 6) 中, ba 铋合金 (E电池) 的 emf 值是相对于纯 ba 金属5确定的。
钡铋合金的 emf 值, 相对于纯 ba (s), 被绘制为每个电极组成的温度函数, 如图 7所示, 所选 ba-铋合金 (xba = 0.05-0.25)5。从电磁场数据绘制与温度的线性拟合出发, 利用以下热力学方程计算了部分摩尔熵的变化: 
<img alt="Equation 13" src="/files/ftp_upload/56718/56718eq13.jpg"> 在铋中钡的部分摩尔焓可以用热力学关系计算, 如吉布斯-亥姆霍兹方程, 如下所示。结果在表 15中进行了总结。 
<img alt="Equation 14" src="/files/ftp_upload/56718/56718eq14.jpg">
钡的活性也被确定使用收集的 emf 值和能方程: 
<img alt="Equation 15" src="/files/ftp_upload/56718/56718eq15.jpg"> 结果在表 25中进行了总结。
ba 铋合金 (xba = 0.05-0.80) 的 Emf 值也用于确定每个合金成分的相变温度。结合差分扫描量热法 (DSC) 相变数据, 电感耦合等离子体原子发射光谱 (icp-aes) 合成数据, 类似于表 312中显示的那样, 以及晶体结构从 XRD 分析数据, emf 数据被用来提炼最新的 Ba-双相图报告的冈本 (图 8)5,11。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56718/56718fig1.jpg"> 
图 1: 单相 CaF2-战略成果框架2电解质 XRD 谱.对 CaF2-在烧结前后的2电解质的 XRD 谱 (归一化至最强烈的峰值)。提供了纯 (*) CaF2和 "战略成果框架"2衍射模式进行比较。此图已从 Smith et al.中修改9 <a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56718/56718fig2.jpg"> 
图 2: a-b 碱性地球液态金属合金的电化学电池.电化学电池组件的示意图, 用于电磁场测量电解质、电解质帽、电极材料、钨引线和热电偶 (TC)。6 a B 合金中的两个是参考电极, 4 是工作电极。<a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56718/56718fig3.jpg"> 
图 3: 电磁场测量的电化学设置说明电化学电池组件和相关部件的正常操作条件。<a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56718/56718fig4.jpg"> 
图 4: 实验装置的仪表图.冷却水的示意图 (实心, 粗体), 氩 (固体, 薄), 和真空 (虚线) 流体流经 emf 测量系统。<a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/56718/56718fig5.jpg"> 
图 5: 钡铋合金的电化学电磁场测量 (xba = 0.05-0.20).电动势 (E1) 和在冷却和再加热时被测量为时间函数的温度 ba 双 (xba = 0.05) |CaF2-曝气生物滤池2|ba 双 (xBa = 0.05、0.10 和 0.20) 单元格。此图已从列支敦士登et al.中修改5 <a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/56718/56718fig6.jpg"> 
图 6: 纯 ba vs 钡铋合金(xBa = 0.05) emf 值校准。电动势 (EII) 用 Ba (s) 测量为温度函数 |CaF2-曝气生物滤池2|ba 双 (xBa = 0.05) 单元格。此图已从列支敦士登et al.中修改5 <a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/56718/56718fig7.jpg"> 
图 7: 钡铋合金 (xba = 0.05-0.25) 的 Emf 测量.电动势 (E单元格) 作为 ba 铋合金的温度函数, 在xba = 0.05、0.10、0.15、0.20 和0.25 基于 ba (s) |CaF2-曝气生物滤池2|Ba 双 (XBa = 0.05-0.25), 其中实线表示线性拟合。此图已从列支敦士登et al.中修改5 <a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig7large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/56718/56718fig8.jpg"> 
图 8: Ba-双相图.实验确定了基于电磁场测量的 ba-铋相图, 辅以钡铋合金的 DSC 和 XRD 表征, 其中 (rt) 和 (ht) 分别代表室温和高温。此图已从列支敦士登et al.中修改5 <a href="//ecsource.jove.com/files/ftp_upload/56718/56718fig8large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>x Ba</td>
			<td>T (K)</td>
			<td>∂E单元格/∂T (μ K\ u20121)</td>
			<td>∂ (E单元格/t)/∂ (1/t) (mV)</td>
			<td><img alt="Equation 16" src="/files/ftp_upload/56718/56718eq16.jpg">(J 摩尔\n u20121 K\n u20121)</td>
			<td><img alt="Equation 17" src="/files/ftp_upload/56718/56718eq17.jpg">(焦摩尔\n u20121)</td>
		</tr>
		<tr>
			<td>0.05</td>
			<td>707-938</td>
			<td>197±6</td>
			<td>1011±5</td>
			<td>38</td>
			<td>-195。1</td>
		</tr>
		<tr>
			<td>0。1</td>
			<td>704-1048</td>
			<td>137±1</td>
			<td>1031±1</td>
			<td>26。4</td>
			<td>-199</td>
		</tr>
		<tr>
			<td>0.15</td>
			<td>728-1048</td>
			<td>125±2</td>
			<td>1005±2</td>
			<td>24。1</td>
			<td>-193。9</td>
		</tr>
		<tr>
			<td>0。2</td>
			<td>809-1048</td>
			<td>94±7</td>
			<td>984±6</td>
			<td>18。1</td>
			<td>-189。9</td>
		</tr>
		<tr>
			<td>0.25</td>
			<td>881-1048</td>
			<td>73.4 ±5</td>
			<td>961±5</td>
			<td>14。2</td>
			<td>-185。4</td>
		</tr>
		<tr>
			<td>0.25</td>
			<td>704-881</td>
			<td>-480 ±14</td>
			<td>1448±13</td>
			<td>-92。6</td>
			<td>-279。4</td>
		</tr>
	</tbody>
</table>
表 1: 钡铋合金的热力学性质 (xba = 0.05-0.25).在部分摩尔熵 () 和部分摩尔焓 () 中更改 ba-铋合金成分<img alt="Equation 17" src="/files/ftp_upload/56718/56718eq17.jpg"> x<img alt="Equation 16" src="/files/ftp_upload/56718/56718eq16.jpg">ba = 0.05 到xba = 0.25 从 emf 值的线性拟合计算, 其中的斜率和截取分别为和. <img alt="Equation 18" src="/files/ftp_upload/56718/56718eq18.jpg"> <img alt="Equation 19" src="/files/ftp_upload/56718/56718eq19.jpg"> </img>此表已从列支敦士登et al中修改。5
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td rowspan="2">x Ba</td>
			<td colspan="3">E (V)</td>
			<td colspan="3">在 a Ba</td>
		</tr>
		<tr>
			<td>773 K</td>
			<td>873 K</td>
			<td>973 K</td>
			<td>773 K</td>
			<td>873 K</td>
			<td>973 K</td>
		</tr>
		<tr>
			<td>0.05</td>
			<td>1.164</td>
			<td>1.183</td>
			<td>1.203</td>
			<td>-35</td>
			<td>-31。5</td>
			<td>-28。7</td>
		</tr>
		<tr>
			<td>0.10</td>
			<td>1.137</td>
			<td>1.15</td>
			<td>1.164</td>
			<td>-34。1</td>
			<td>-30。6</td>
			<td>-27。8</td>
		</tr>
		<tr>
			<td>0.15</td>
			<td>1.101</td>
			<td>1.114</td>
			<td>1.127</td>
			<td>-33</td>
			<td>-29。6</td>
			<td>-26。9</td>
		</tr>
		<tr>
			<td>0.20</td>
			<td>1.075</td>
			<td>1.066</td>
			<td>1.076</td>
			<td>-32。2</td>
			<td>-28。3</td>
			<td>-25。7</td>
		</tr>
		<tr>
			<td>0.25</td>
			<td>1.075</td>
			<td>1.027</td>
			<td>1.032</td>
			<td>-32。2</td>
			<td>-27。3</td>
			<td>-24。6</td>
		</tr>
	</tbody>
</table>
表 2: 测量的 emf 值 (E) 和铋中钡活性的自然记录 (ln Ba).ba 铋合金 (xba = 0.05-0.25) 与 ba (s) 和钡在铋中的活性自然测井值 (773 k、873 k 和 973 k) 的测量电势。此表已从列支敦士登et al.中修改5
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="2">摩尔分数, x Ba</td>
		</tr>
		<tr>
			<td>名义</td>
			<td>测量</td>
		</tr>
		<tr>
			<td>0.03</td>
			<td>0.03</td>
		</tr>
		<tr>
			<td>0.05</td>
			<td>0.05</td>
		</tr>
		<tr>
			<td>0.10</td>
			<td>0.09</td>
		</tr>
		<tr>
			<td>0.15</td>
			<td>0.14</td>
		</tr>
		<tr>
			<td>0.20</td>
			<td>0.20</td>
		</tr>
		<tr>
			<td>0.25</td>
			<td>0.25</td>
		</tr>
		<tr>
			<td>0.30</td>
			<td>0.30</td>
		</tr>
	</tbody>
</table>
表 3:Ba 锑二元合金的标称和测量钡含量.Ba 锑二元合金的标称和测定钡含量。用电感耦合等离子体原子 emissio 确定 Ba 锑合金的钡含量n 光谱学 (icp-aes)。此表已从列支敦士登et al.中修改12

Watch this Scientific Journal Video about Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique at JoVE.com

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

本协议描述了在高温 (723-1、123 K) 的液态金属合金中碱土金属元素的电动势的测量, 以确定其热力学性质, 包括活性、部分摩尔熵、部分摩尔焓, 和相变温度, 在广泛的组成范围。

用电动势技术测定碱土金属合金的热力学性质

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

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13.1K 次观看.  The Pennsylvania State University. 本协议描述了在高温 (723-1、123 K) 的液态金属合金中碱土金属元素的电动势的测量, 以确定其热力学性质, 包括活性、部分摩尔熵、部分摩尔焓, 和相变温度, 在广泛的组成范围。

视频: Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

金属硅酸盐分区在高压和高温:实验方法和协议，以抑制高亲铁元素元素夹杂物

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

科研

化学

Ultrasound Velocity Measurement in a Liquid Metal Electrode

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within &#177;2 &#176;C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries.

Ultrasound velocimetry is used to study mixing by fluid flow in liquid metal electrodes. The focus of this manuscript is to illustrate the methods used for making precise, spatially-resolved ultrasound measurements while limiting oxidation and controlling and monitoring temperature, applied current, and the heater power being supplied.

超声速度测量的液态金属电极

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently ...

工程学

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.
Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.
Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( &#820;500 mN/m to near zero). Furthermore, this method requires only a very modest potential (&#60; 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests.

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

方法通过表面氧化还原操纵液态金属的表面张力

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

Metal Corrosion and the Efficiency of Corrosion Inhibitors in Less Conductive Media

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, prevent them and minimize the damages associated with them. One of the most important characteristics of corrosion processes is the corrosion rate. The measurement of corrosion rates is often very difficult or even impossible especially in less conductive, non-aqueous environments such as biofuels. Here, we present five different methods for the determination of corrosion rates and the efficiency of anti-corrosion protection in biofuels: (i) a static test, (ii) a dynamic test, (iii) a static test with a reflux cooler and electrochemical measurements (iv) in a two-electrode arrangement and (v) in a three-electrode arrangement. The static test is advantageous due to its low demands on material and instrumental equipment. The dynamic test allows for the testing of corrosion rates of metallic materials at more severe conditions. The static test with a reflux cooler allows for the testing in environments with higher viscosity (e.g., engine oils) at higher temperatures in the presence of oxidation or an inert atmosphere. The electrochemical measurements provide a more comprehensive view on corrosion processes. The presented cell geometries and arrangements (the two-electrode and three-electrode systems) make it possible to perform measurements in biofuel environments without base electrolytes that could have a negative impact on the results and load them with measurement errors. The presented methods make it possible to study the corrosion aggressiveness of an environment, the corrosion resistance of metallic materials, and the efficiency of corrosion inhibitors with representative and reproducible results. The results obtained using these methods can help to understand corrosion processes in more detail to minimize the damages caused by corrosion.

The testing of processes associated with material corrosion can often be difficult especially in non-aqueous environments. Here, we present different methods for short-term and long-term testing of corrosion behavior of non-aqueous environments such as biofuels, especially those containing bioethanol.

金属腐蚀与腐蚀抑制剂在低导电介质中的效率

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, ...

环境科学

Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature

The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion batteries for use in devices operating at elevated temperatures require thermally stable and non-flammable electrolytes. Ionic liquids (ILs), which are non-flammable, non-volatile, thermally stable molten salts, are an ideal replacement for flammable and low boiling point organic solvent electrolytes currently used today. We herein describe the procedures to: 1) synthesize mono- and di-phosphonium ionic liquids paired with chloride or bis(trifluoromethane)sulfonimide (TFSI) anions; 2) measure the thermal properties and stability of these ionic liquids by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); 3) measure the electrochemical properties of the ionic liquids by cyclic voltammetry (CV); 4) prepare electrolytes containing lithium bis(trifluoromethane)sulfonamide; 5) measure the conductivity of the electrolytes as a function of temperature; 6) assemble a coin cell battery with two of the electrolytes along with a Li metal anode and LiCoO2 cathode; and 7) evaluate battery performance at 100 &#176;C. We additionally describe the challenges in execution as well as the insights gained from performing these experiments.

Here, we describe protocols to prepare phosphonium-based ionic liquid and lithium bis(trifluoromethane)sulfonimide salt electrolytes, and assemble a non-flammable and high temperature functioning lithium-ion coin cell battery.

离子液体基电解质的合成，装配锂离子电池，并在高温性能的测量

The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion ...

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 ...

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation. This difficulty arises in part from the fact that any electrochemical measurement of a battery will return the combined contributions of all components in the cell. Incorporation of a reference electrode can solve part of the problem, as it allows the electrochemical reactions of the cathode and the anode to be individually probed. A variation in the voltage range experienced by the cathode, for example, can indicate alterations in the pool of cyclable lithium ions in the full-cell. The structural evolution of the many interphases existing in the battery can also be monitored, by measuring the contributions of each electrode to the overall cell impedance. Such wealth of information amplifies the reach of diagnostic analysis in Li-ion batteries and provides valuable input to the optimization of individual cell components. In this work, we introduce the design of a test cell able to accommodate multiple reference electrodes, and present reference electrodes that are appropriate for each specific type of measurement, detailing the assembly process in order to maximize the accuracy of the experimental results.

The incorporation of reference electrodes in a Li-ion battery provides valuable information to elucidate degradation mechanisms at high voltages. In this article, we present a cell design that accommodates multiple reference electrodes, along with the assembly steps to assure maximum accuracy of the data obtained in electrochemical measurements.

原位锂化参考电极: 四原位阻抗谱的电极设计

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate ...

Identification and Quantification of Decomposition Mechanisms in Lithium-Ion Batteries; Input to Heat Flow Simulation for Modeling Thermal Runaway

The risks and possible accidents related to the normal use of lithium-ion batteries remain a serious concern. In order to get a better understanding of thermal runaway (TR), the exothermic decomposition reactions in anode and cathode were studied, using a Simultaneous Thermal Analysis (STA)/Gas Chromatography-Mass Spectrometry (GC-MS)/Fourier Transform Infrared (FTIR) spectrometer system. These techniques allowed the identification of the reaction mechanisms in each electrode, owing to the analysis of evolved gaseous species, the amount of heat released and mass loss. These results provided insight into the thermal events happening within a broader temperature range than covered in previously published models. This allowed the formulation of an improved thermal model to depict TR. The heat of reaction, activation energy, and frequency factor (thermal triplets) for each major exothermic process at material level were investigated in a Lithium Nickel-Manganese-Cobalt-Oxide (NMC (111))-Graphite battery cell. The results were analyzed, and their kinetics were derived. These data can be used to successfully simulate the experimental heat flow.

This work aims at determining the reaction kinetics of Li-ion battery cathode and anode materials undergoing thermal runaway (TR). Simultaneous Thermal Analysis (STA)/Fourier Transform Infrared (FTIR) spectrometer/Gas Chromatography Mass Spectrometry (GC-MS) were used to reveal thermal events and to detect evolved gases.

锂离子电池分解机理的鉴定和量化;用于模拟热失控的热流仿真输入

The risks and possible accidents related to the normal use of lithium-ion batteries remain a serious concern. In order to get a better understanding of ...

Co-localizing Kelvin Probe Force Microscopy with Other Microscopies and Spectroscopies: Selected Applications in Corrosion Characterization of Alloys

Kelvin probe force microscopy (KPFM), sometimes referred to as surface potential microscopy, is the nanoscale version of the venerable scanning Kelvin probe, both of which measure the Volta potential difference (VPD) between an oscillating probe tip and a sample surface by applying a nulling voltage equal in magnitude but opposite in sign to the tip-sample potential difference. By scanning a conductive KPFM probe over a sample surface, nanoscale variations in surface topography and potential can be mapped, identifying likely anodic and cathodic regions, as well as quantifying the inherent material driving force for galvanic corrosion.
Subsequent co-localization of KPFM Volta potential maps with advanced scanning electron microscopy (SEM) techniques, including back scattered electron (BSE) images, energy dispersive spectroscopy (EDS) elemental composition maps, and electron backscattered diffraction (EBSD) inverse pole figures can provide further insight into structure-property-performance relationships. Here, the results of several studies co-localizing KPFM with SEM on a wide variety of alloys of technological interest are presented, demonstrating the utility of combining these techniques at the nanoscale to elucidate corrosion initiation and propagation.
Important points to consider and potential pitfalls to avoid in such investigations are also highlighted: in particular, probe calibration and the potential confounding effects on the measured VPDs of the testing environment and sample surface, including ambient humidity (i.e., adsorbed water), surface reactions/oxidation, and polishing debris or other contaminants. Additionally, an example is provided of co-localizing a third technique, scanning confocal Raman microscopy, to demonstrate the general applicability and utility of the co-localization method to provide further structural insight beyond that afforded by electron microscopy-based techniques.

Kelvin probe force microscopy (KPFM) measures surface topography and differences in surface potential, while scanning electron microscopy (SEM) and associated spectroscopies can elucidate surface morphology, composition, crystallinity, and crystallographic orientation. Accordingly, the co-localization of SEM with KPFM can provide insight into the effects of nanoscale composition and surface structure on corrosion.

开尔文探针力显微镜与其他显微镜和光谱学共定位:合金腐蚀表征中的选定应用

Kelvin probe force microscopy (KPFM), sometimes referred to as surface potential microscopy, is the nanoscale version of the venerable scanning Kelvin ...

氧化还原活性 MOF 固态电化学的磁力表征

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs show outstanding performance in terms of gravimetric or areal capacitance and cyclic stability, unfortunately their electrochemical mechanisms are not well understood in most cases. Traditional spectroscopic techniques, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), have only provided vague and qualitative information about valence changes of certain elements, and the mechanisms proposed based on such information are often highly disputable. In this article, we report a series of standardized methods, including the fabrication of solid-state electrochemical cells, electrochemistry measurements, the disassembly of cells, the collection of MOF electrochemical intermediates, and physical measurements of the intermediates under the protection of inert gases. By using these methods for quantitatively clarifying the electronic and spin state evolution within a single electrochemical step of redox-active MOFs, one can provide clear insight into the nature of electrochemical energy storage mechanisms not only for MOFs, but also for all other materials with strongly correlated electronic structures.

作者聚焦：氧化还原活性金属有机框架固态电化学中中间体的磁力表征  

Ex situ magnetic surveys can directly provide bulk and local information on a magnetic electrode to reveal its charge storage mechanism step by step. Herein, electron spin resonance (ESR) and magnetic susceptibility are demonstrated to monitor the evaluation of paramagnetic species and their concentration in a redox-active metal-organic framework (MOF).

氧化还原-活性金属-有机骨架固态电化学中中间体的磁力表征

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs ...

用电动势技术测定碱土金属合金的热力学性质

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