这项工作是由国家科学基金会资助的一部分。DMR-0420785 (XPS)。我们感谢密歇根大学的密歇根材料鉴定中心 (MC)2, 为其提供 XPS 和密歇根大学 Van Vlack 实验室的 XRD。我们还要感谢托马斯. Kratofil 对散装材料的准备工作的协助。

注意: 佩戴必要的个人防护设备 (PPE), 包括近趾鞋、全长长裤、安全眼镜、微粒过滤面罩、实验室大衣和手套, 因为氧化物粉末会对皮肤接触刺激和眼部接触刺激产生风险。在开始之前, 请查阅所有相关的材料安全数据表以补充 PPE 要求。应使用工程控制 (如油烟机) 进行综合。
1. 熵稳定氧化物的批量合成
<ol><li>
组成氧化物粉体的质量计算
	<ol>
<li>通过将所需体积乘以组成二元氧化物的平均密度, 估计目标的总期望质量。 <img alt="Equation 3" src="/files/ftp_upload/57746/57746eq3v2.jpg"> <img alt="Equation 4" src="/files/ftp_upload/57746/57746eq4.jpg"> 其中和是摩尔分数和 th 组件的密度. <img alt="Equation 5" src="/files/ftp_upload/57746/57746eq5.jpg"> <img alt="Equation 6" src="/files/ftp_upload/57746/57746eq6.jpg"> <img alt="Equation 7" src="/files/ftp_upload/57746/57746eq7.jpg"> </img>对于1英寸 (2.54 厘米) 直径、⅛ (0.3175 厘米) 厚的样本, 目标卷为1.7 厘米<img alt="Equation 8" src="/files/ftp_upload/57746/57746eq8.jpg"> </img>3。</li>
		<li>通过将该目标质量除以组成二进制氧化物的平均摩尔质量来确定每个分量所需的摩尔。 <img alt="Equation 9" src="/files/ftp_upload/57746/57746eq9v2.jpg"> <img alt="Equation 10" src="/files/ftp_upload/57746/57746eq10.jpg"> 其中是 th 组件的摩尔质量. <img alt="Equation 11" src="/files/ftp_upload/57746/57746eq11.jpg"> <img alt="Equation 7" src="/files/ftp_upload/57746/57746eq7.jpg"> </img>将摩尔数 () 转换回克<img alt="Equation 12" src="/files/ftp_upload/57746/57746eq12.jpg"> </img> <img alt="Equation 13" src="/files/ftp_upload/57746/57746eq13.jpg"> 注: 在表 1和2中, 在这里合成的材料的大量成分和目标成分。</li>
	</ol>
</li>
	<li>
氧化物粉末的预处理
	<ol>
<li>用20毫升的王水 (HNO3 + 3 HCl) 蚀刻来清洁玛瑙杵和砂浆。将酸倒入砂浆中, 用杵研磨, 直到底部清晰。正确处理酸, 用水冲洗。</li>
		<li>结合0.559 克氧化镁, 1.103 克首席运营官, 1.035 克 NiO, 1.103 克的厝, 和 1.129 g 的氧化锌 (为摩尔组成) 粉末在清洁砂浆。</li>
		<li>使用清洁杵, 研磨粉末使用顺时针运动20回合, 然后20逆时针转弯。重复此过程至少45分钟. 使用清洁金属铲去除砂浆两侧的粉末, 并将粉末刷到砂浆的中心。 注: 粉体混合和研磨完成时, 粉末是均匀的, 灰黑色的颜色, 显得细腻的地面, 并感觉光滑。</li>
		<li>将粉末转移到一个干净的, 密封的集装箱运输。</li>
	</ol>
</li>
	<li>
陶瓷颗粒冲压 注意事项: 在装配模具时戴上手套和安全眼镜, 同时使用印刷机。在干净的纸表面上执行整个模具清洗和装配步骤。使用的组件显示在图 2中。<ol>
<li>用矿物油润滑小底柱塞的侧面和内部面 (在图 2a和2b中标记为 C), 并将其插入模具缸内, 直到其底部齐平。</li>
		<li>将一张称重纸滚入模具的腔内, 使模具的两侧覆盖。将粉末倒入模具底部。不允许小柱塞从模具中脱落, 轻轻地敲击柜台上的部件, 以除去任何气囊, 并使粉末水平。小心地取下重纸。</li>
		<li>将少量丙酮加入模具腔内的粉末中, 形成浆料。这使得在目标处于压力下的谷物流动, 并抑制空洞的形成。</li>
		<li>用石蜡油润滑柱塞的两侧和内部面 (B 在图 2a和2b中), 小心不要干扰粉末。将此部件插入模具中。将组装后的模具放到按图 2c所示的压机中, 包括顶部和底部板 (图 2a和 2b中的部件 D), 以提供均匀曲面。</li>
		<li>放置模子在冷的单轴压机。泵压臂直到200兆帕到达。允许压力机在压缩状态下坐20分钟。当粉末 densifies 时, 压力会随时间而松弛。根据需要增加压力, 以维持200兆帕在按压期间。擦去任何过剩的溶剂, 泄漏出的模具。</li>
		<li>释放压力。小心地卸下顶部和底部板。定位拆卸护套和拆卸活塞, 如图 2c所示。按慢, 在暴露被压目标之前, 从组件中卸下小模片。仔细按程序集, 直到目标从模具中暴露出来。小心地去除绿色的身体和转移到坩埚为烧结。</li>
	</ol>
</li>
	<li>
陶瓷烧结 注意: 目标材料将从高温淬火。从热炉中取出坩埚时, 应佩戴耐热手套和面罩。<ol>
<li>获得一个氧化铝坩埚, 将适合按下的粉末和2毫米层钇稳定的氧化锆 (YSZ) 0.1–0.2 毫米珠。用 YSZ 珠涂上坩埚的底部。 注: 涂层厚度应约为2毫米, 以确保目标不接触坩埚底部。</li>
		<li>慢慢地, 小心地把被压的目标转移到坩埚的中心。</li>
		<li>使用金属钳, 小心地将坩埚输送到烧结炉。将温度提高到1100摄氏度, 在50°c 最小-1。烧结的目标为24小时在1100摄氏度的空气气氛。</li>
		<li>在摄氏1100摄氏度时, 将坩埚从炉中取出。使用钳子, 在室温水中快速淬火目标。目标将溅射三十年代, 然后从水中取出, 并设置为干燥。</li>
		<li>一旦目标冷却和干燥, 请测量目标密度, 并与1部分计算的理论值 () 进行比较. <img alt="Equation 14" src="/files/ftp_upload/57746/57746eq14v2.jpg"> </img>测量以前使用的天平上的目标质量, 用卡尺测量尺寸。被测密度与估计值的比值,, 给出了理论密度的百分比. <img alt="Equation 15" src="/files/ftp_upload/57746/57746eq15.jpg"> </img> 注: 合成后, 密度通常为80% 的理论密度。</li>
		<li>为了提高密度, 柄用杵和砂浆对烧结靶进行了处理, 并从步进1.2.3 中重复了批量合成过程。第二次烧结后, 确定目标的密度。 注: 通常测量的密度为理论密度, 适用于脉冲激光沉积 (PLD). <img alt="Equation 16" src="/files/ftp_upload/57746/57746eq16.jpg"></li>
	</ol>
</li>
</ol>2. ESO 单晶薄膜的 PLD
<ol><li>
目标准备
	<ol>
<li>在步骤1中合成的散装陶瓷球团现在将作为沉积源 (目标)。用碳化硅纸的渐进 (320/600/800/1200) 研磨剂在圆形运动中抛光目标, 直到表面反射均匀。</li>
		<li>将目标放在燃烧室内的旋转旋转木马上, 并将一张2厘米 x 2 厘米的烧纸放在光束路径的最终目标上。</li>
		<li>通过在目标上射击单个射击并测量两个轴上的结果烧伤标记, 测量激光光斑的大小。如果光斑大小不正确, 请调整聚焦透镜 (图 3a)。调整测量的光斑大小, 直到实现两个轴的椭圆、0.27 厘米 x 0.24 厘米。</li>
		<li>卸下烧纸, 关上门进行疏散。使用干式滚动粗加工泵将燃烧室疏散到 6.7 Pa 的压力, 此时涡轮泵可以旋转高达1000赫兹的速率。</li>
		<li>将该腔体泵出至至少 1.3 x 10-5 Pa 的基本压力 (由离子表测量)。一旦达到, 减少涡轮增压速度为200赫兹, 允许使用过程中的气体在成长过程中。</li>
	</ol>
</li>
	<li>
衬底制备
	<ol>
<li>在半导体级三氯乙烯 (TCE)、半导体级丙酮和高纯度异丙醇 (IPA) 中, 用超声波清洁一个单晶, 一边抛光, 0.5 毫米厚的氧化镁衬底。</li>
		<li>用超干的、压缩的 N2气体将衬底吹掉, 然后用少量导热银漆将基板连接到基板 (图 3b) 上。在热板上加热基板和压板到摄氏10分钟以固化银漆。</li>
		<li>使用外部转移工具, 将衬底架放在所述腔内负载锁的转移臂上, 然后将该腔体密封并泵出, 使其至少 1.3 x 10-4宾夕法尼亚州的压力。</li>
		<li>通过打开两个之间的闸阀并使用转移臂将基板放在加热器组件上, 将基板转移到生长室中。</li>
		<li>将转移臂收回到负载锁中并密封闸门。使用燃烧室顶部的螺钉总成将加热器降低。</li>
	</ol>
</li>
	<li>
激光能量和剂量 注: 沉积是由248纳米 KrF 脉冲准分子激光辐照启用的。激光脉冲宽度为 20 ns。<ol>
<li>在进入会议厅之前, 请使用放置在光束路径中的能量计测量激光能量 (图 3a)。用50脉冲在2赫兹的速率照射光电二极管后, 确定平均能量。</li>
		<li>改变激光器的励磁电压, 直到310兆焦耳的平均脉冲能量达到10兆焦耳的稳定性。从光束路径中取出能量计, 使激光进入腔室。 注: 使用10% 室窗口的激光衰减, 上面的配置给出 2.55 J 厘米-2的通量。这项工作的基板目标距离为7厘米。不同的基底靶差可能改变理想的沉积条件和生长速率。</li>
	</ol>
</li>
	<li>
沉积
	<ol>
<li>在生长前, 将基体加热到1000摄氏度, 在真空中以30分钟为30摄氏度 (-1 ), 以 dehydroxylize 氧化镁晶体表面。将温度降低到300摄氏度, 在30°最小-1 , 并允许平衡为10分钟。 注意: 我们报告的温度是由加热器块内的热电偶决定的。</li>
		<li>超高纯度流量 (99.999%)O2气体进入燃烧室, 达到6.7 宾夕法尼亚州的压力 注: 当氧气进入腔室时, 压力是用 barotron 计测量的。采用质量流量控制器引入气体, 作为闭环系统的一部分, 在生长过程中稳定燃烧室压力。</li>
		<li>清理所有残留污染物的目标, 并通过预烧来准备它们的生长。将所选目标设置为光栅和旋转, 以使激光器每次不击中同一点, 确保基板快门闭合, 并以5赫兹的速率消融目标2000脉冲。 注: 目标已准备就绪, 系统处于正确的沉积条件 (温度、压力、通量)。</li>
		<li>在沉积前打开快门。在这种情况下, 1万脉冲在6赫兹产生一个 ~ 80 nm 厚膜。 注意: 此增长率由前一工作16中的 X 射线反射率确定。</li>
		<li>沉积后, 增加氧分压至 133 Pa (1.0 乇), 以抑制氧空位的形成。将样品温度降低到40摄氏度, 在10°min-1。一旦达到40摄氏度, 关闭氧气的流动, 并在压力稳定后, 打开在成长室和负载锁之间的闸阀。抬起加热器, 使用转移臂将基体板从组件中移回负载锁中。</li>
		<li>将负载锁发泄到大气中, 并使用外部传输工具删除该示例。用刀片将样品从压板上取下, 然后擦亮压板, 取下剩余的银漆和沉积物。重复步骤2.2 开始的过程以增加胶片的生长。</li>
	</ol>
</li>
</ol>

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<li>Eres, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Time-resolved+study+of+SrTiO3+homoepitaxial+pulsed-laser+deposition+using+surface+x-ray+diffraction%5BTitle%5D)+AND+%22Appl+Phys+Lett%22%5BJournal%5D)">Time-resolved study of SrTiO3 homoepitaxial pulsed-laser deposition using surface x-ray diffraction.</a> Appl Phys Lett. 80 (18), 3379-3381 (2002).</li>
<li>Fleet, A., Dale, D., Suzuki, Y., Brock, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Observed+Effects+of+a+Changing+Step-Edge+Density+on+Thin-Film+Growth+Dynamics%5BTitle%5D)+AND+%22Phys+Rev+Lett%22%5BJournal%5D)">Observed Effects of a Changing Step-Edge Density on Thin-Film Growth Dynamics.</a> Phys Rev Lett. 94 (3), 036102(2005).</li>
<li>Luca, G. D., Strkalj, N., Manz, S., Bouillet, C., Fiebig, M., Trassin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Nanoscale+design+of+polarization+in+ultrathin+ferroelectric+heterostructures%5BTitle%5D)+AND+%22Nat+Commun%22%5BJournal%5D)">Nanoscale design of polarization in ultrathin ferroelectric heterostructures.</a> Nat Commun. 8 (1), 1419(2017).</li>
<li>De Luca, G., Rossell, M. D., Schaab, J., Viart, N., Fiebig, M., Trassin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Domain+Wall+Architecture+in+Tetragonal+Ferroelectric+Thin+Films%5BTitle%5D)+AND+%22Adv+Mater%22%5BJournal%5D)">Domain Wall Architecture in Tetragonal Ferroelectric Thin Films.</a> Adv Mater. 29 (7), (2017).</li>
<li>Gruenewald, J. H., Nichols, J., Seo, S. S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pulsed+laser+deposition+with+simultaneous+in+situ+real-time+monitoring+of+optical+spectroscopic+ellipsometry+and+reflection+high-energy+electron+diffraction%5BTitle%5D)+AND+%22Rev+Sci+Instrum%22%5BJournal%5D)">Pulsed laser deposition with simultaneous in situ real-time monitoring of optical spectroscopic ellipsometry and reflection high-energy electron diffraction.</a> Rev Sci Instrum. 84 (4), 043902(2013).</li>
<li>MDC Vacuum Products | Vacuum Components, Chambers, Valves, Flanges & Fittings. , 
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<li>Dijkkamp, D., et al. <a target="_blank" href="http://aip.scitation.org/doi/abs/10.1063/1.98366">Preparation of Y-Ba-Cu oxide superconductor thin films using pulsed laser evaporation from high Tc bulk material.</a> Appl Phys Lett. 51 (8), 619-621 (1987).</li>
<li>Biegalski, M. D., et al. <a target="_blank" href="http://aip.scitation.org/doi/full/10.1063/1.2198088">Relaxor ferroelectricity in strained epitaxial SrTiO3 thin films on DyScO3 substrates.</a> Appl Phys Lett. 88 (19), 192907(2006).</li>
<li>Schlom, D. G., Chen, L. Q., Pan, X., Schmehl, A., Zurbuchen, M. A. <a target="_blank" href="http://onlinelibrary.wiley.com/doi/10.1111/j.1551-2916.2008.02556.x/abstract">A Thin Film Approach to Engineering Functionality into Oxides.</a> J Am Ceram Soc. 91 (8), 2429-2454 (2008).</li>
<li>Damodaran, A. R., Breckenfeld, E., Chen, Z., Lee, S., Martin, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Enhancement+of+Ferroelectric+Curie+Temperature+in+BaTiO3+Films+via+Strain-Induced+Defect+Dipole+Alignment%5BTitle%5D)+AND+%22Adv+Mater%22%5BJournal%5D)">Enhancement of Ferroelectric Curie Temperature in BaTiO3 Films via Strain-Induced Defect Dipole Alignment.</a> Adv Mater. 26 (36), 6341-6347 (2014).</li>
</ol>

我们没有什么可透露的。

我们已经描述并显示了一个合成散装和高质量的协议, 单晶薄膜 (镁0.25 (1 x)Cox镍0.25 (1 x)铜0.25 (1 x)锌0.25 (1 x)) O (x = 0.20, 0.27、0.33) 和 (Mg0.25 (1-x)Co0.25 (1 x)Ni0.25 (1 x)铜x锌0.25 (1 x)) O (x = 0.11, 0.27) 熵稳定氧化物。我们期望这些合成技术适用于广泛的熵稳定氧化物组成, 更多的发现, 在发展和扩大的领域。此外, 组分变化的熵?...

自2004年发现高熵金属合金以来, 高熵材料引起了极大的兴趣, 原因是硬度增加了1,2,3, 韧性4,5和耐腐蚀性3,6。最近发现了高熵氧化物7、8和硼化物9, 为物质爱好者开辟了一个大操场。特别是氧化物可以显示有用和动态功能属性, 如铁电性10、磁电11、12、热电 13和超导14。.熵稳定氧化物 (ESOs) 最近被证明具有有趣的, 组分依赖功能属性15,16, 尽管有重大的障碍, 使这种新的材料类特别令人兴奋。
熵稳定材料是化学上均匀的, 多组分 (通常有五个或更多组分), 单相材料在那里构型熵贡献 () 对吉布斯自由能 () 是重要的<img alt="Equation 1" src="/files/ftp_upload/57746/57746eq1.jpg"><img alt="Equation 2" src="/files/ftp_upload/57746/57746eq2.jpg">足以推动形成单相固体溶液17。合成多组分 ESOs, 其中阳离子构型紊乱是在阳离子点观察, 需要精确控制的组成, 温度, 沉积速率, 淬火速率和淬火温度7,16.该方法旨在使从业者能够合成相纯和化学均质的熵稳定氧化物陶瓷小球和相纯, 单晶, 平面薄膜的期望化学计量。可以用大于90% 的理论密度合成大块材料, 从而对电子、磁性和结构特性进行研究, 或用作薄膜物理气相沉积 (PVD) 技术的来源。由于在这里考虑的熵稳定氧化物有五阳离子, 薄膜 PVD 技术, 采用五来源, 如分子束外延 (外延) 或共溅射, 将提出的挑战, 沉积化学均匀薄膜流量漂移。该协议的结果是在化学上均质, 单晶, 扁平 (方根) 粗糙度的 0.15 nm 的熵稳定氧化物薄膜从单一的材料来源, 这表明具有名义化学成分。该薄膜合成协议可通过包含原位电子或光学特性技术来增强, 用于实时监测合成和精制质量控制。这种方法的预期限制来源于激光能量漂移, 这可能会限制高质量薄膜厚度低于1微米。
尽管薄膜氧化物材料的生长和表征有显著的进步10,18,19,20,21, 立体与氧化物中的电子结构可以导致在最终材料中产生显著的差异, 这是由看似微不足道的方法论差异引起的。此外, 多组分熵稳定氧化物的领域是相当新生的, 仅二个当前报告薄膜综合在文献7,16。ESOs 对这个过程特别好, 规避了化学气相沉积和分子束外延所带来的挑战。在这里, 我们提供了一个详细的综合协议的散装和薄膜 ESOs (图 1), 以尽量减少材料处理困难, 意外的财产变化, 并提高发现在外地的加速。

<table><tbody><tr><td>MAGNESIUM OXIDE 99.95%</td><td>Fisher</td><td>AA1468422</td><td></td></tr><tr><td>COBALT(II) OXIDE, 99.995%</td><td>Fisher</td><td>AA4435414</td><td></td></tr><tr><td>NICKEL(II) OXIDE 99.998%</td><td>Fisher</td><td>AA1081914</td><td></td></tr><tr><td>COPPER(II) OXIDE 99.995%</td><td>Fisher</td><td>AA1070014</td><td></td></tr><tr><td>ZINC OXIDE 99.99%</td><td>Fisher</td><td>AA8781230</td><td></td></tr><tr><td>TRICHLROETHLENE SEMICNDTR 9</td><td>Fisher</td><td>AA39744K7</td><td></td></tr><tr><td>ACETONE SEMICNDTR GRD 99.5%</td><td>Fisher</td><td>AA19392K7</td><td></td></tr><tr><td>2-PROPANOL ACS 99.5%</td><td>Fisher</td><td>A416S4</td><td></td></tr><tr><td>Mineral oil, pure</td><td>Acros Organics</td><td>AC415080010</td><td></td></tr><tr><td>alumina crucible</td><td>MTI Corporation</td><td>eq-ca-l50w40h20</td><td></td></tr><tr><td>ZIRCONIA (YSZ) GRINDING MEDIA</td><td>Inframat Advanced Materials</td><td>4039GM-S010</td><td></td></tr><tr><td>SiC paper 320/600/800/1200</td><td>South Bay Technology</td><td>SDA08032-25</td><td></td></tr><tr><td>MgO (100) substrate, 5x5x0.5 mm, 1SP</td><td>MTI Corporation</td><td>MGa050505S1</td><td></td></tr><tr><td>OXYGEN COMPRESSED ULTRA HIGH PURITY GRADE, 99.999%</td><td>Cryogenic Gases</td><td>OXYUHP</td><td></td></tr><tr><td>NITROGEN COMPRESSED EXTRA DRY GRADE</td><td>Cryogenic Gases</td><td>NITEX</td><td></td></tr></tbody></table>

bulk and thin film synthesis of compositionally variant entropy-stabilized oxides

这里, 我们提出了合成散装和薄膜多组分 (镁0.25 (1 x)Cox镍0.25 (1-x)铜0.25 (1-x)锌0.25 (1-x)) O (Co 变体) 和 (毫克0.25 (1 x)Co0.25 (1-x)镍0.25 (1 x)铜x锌0.25 (1-x)) O (cu 变体) 熵稳定氧化物。相纯和化学均质 (毫克0.25 (1 x)Cox镍0.25 (1-x)铜0.25 (1 x)锌0.25 (1 x)) O (x = 0.20, 0.27、0.33) 和 (毫克0.25 (1 x)Co0.25 (1 x)镍0.25 (1 x)Cux锌0.25 (1 x)) O (x = 0.11, 0.27) 陶瓷颗粒被合成并用于沉积超高质量, 相纯, 单晶薄膜的靶化学计量。本文介绍了用脉冲激光沉积 (001) 取向氧化镁基片沉积光滑、化学均匀、熵稳定氧化物薄膜的详细方法。用 X 射线衍射法确定了大块薄膜材料的相和结晶度。通过 x 射线光电子能谱和能量色散 x 射线光谱法证实了成分和化学均匀性。用扫描探针显微镜测量薄膜的表面形貌。合成高质量, 单晶, 熵稳定的氧化物薄膜, 使研究的界面, 大小, 应变和无序影响的性质, 这一新类高无序氧化物材料。

所制备的 X 射线衍射 (XRD) 谱 (Mg0.25 (1 x)Cox镍0.25 (1-x)Cu0.25 (1 x)锌0.25 (1-x)) O (x = 0.20, 0.27, 0.33) 和 (毫克0.25 (1 x)Co0.25 (1-x)镍0.25 (1-x)Cux锌0.25 (1 x)) O (x = 0.11, 0.27) 散装陶瓷 (图 4a) 和沉积薄膜 (图 4b)。这些数据表明, 样品是单相的, 可用于测定晶格常数、?...

Watch this Scientific Journal Video about Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides at JoVE.com

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

高质量的散装和薄膜 (Mg0.25 (1 x)Cox镍0.25 (1-x)铜0.25 (1-x)锌0.25 (1-x)) O 和 (毫克0.25 (1 x)Co0.25 (1 x)镍0.25 (1 x)铜x锌0.25 (1-x)) O 熵稳定氧化物的提出。

组分变熵稳定氧化物的体积和薄膜合成

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...

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Unit 1

The Second Law of Thermodynamics

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9.4K 次观看.  University of Michigan. 高质量的散装和薄膜 (Mg0.25 (1 x)Cox镍0.25 (1-x)铜0.25 (1-x)锌0.25 (1-x)) O 和 (毫克0.25 (1 x)Co0.25 (1 x)镍0.25 (1 x)铜x锌0.25 (1-x)) O 熵稳定氧化物的提出。

视频: Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

制备纳米设计的脉冲激光沉积透明导电氧化物

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

科研

工程学

Fabrication of Spatially Confined Complex Oxides

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from the inherent strong electron correlations that reside within them. These materials can also possess electronic phase separation in which regions of vastly different resistive and magnetic behavior can coexist within a single crystal alloy material. By reducing the scale of these materials to length scales at and below the inherent size of the electronic domains, novel behaviors can be exposed. Because of this and the fact that spin-charge-lattice-orbital order parameters each involve correlation lengths, spatially reducing these materials for transport measurements is a critical step in understanding the fundamental physics that drives complex behaviors. These materials also offer great potential to become the next generation of electronic devices 1-3. Thus, the fabrication of low dimensional nano- or micro-structures is extremely important to achieve new functionality. This involves multiple controllable processes from high quality thin film growth to accurate electronic property characterization. Here, we present fabrication protocols of high quality microstructures for complex oxide manganite devices. Detailed descriptions and required equipment of thin film growth, photo-lithography, and wire-bonding are presented.

We describe the use of pulsed laser deposition (PLD), photolithography and wire-bonding techniques to create micrometer scale complex oxides devices. The PLD is utilized to grow epitaxial thin films. Photolithography and wire-bonding techniques are introduced to create practical devices for measurement purposes.

空间密闭的复合氧化物制备

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

原子定义模板复合氧化物薄膜的外延生长

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

化学

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

写作和氧化物纳米结构的低温特性

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance.
For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application.

We offered a method to directly synthesize high c-axis (0002) ZnO thin film by plasma enhanced chemical vapor deposition. The as-synthesized ZnO thin film combined with Pt interdigitated electrode was used as sensing layer for ultraviolet photodetector, showing a high performance through a combination of its good responsivity and reliability.

合成和高c轴ZnO薄膜等离子体的特性增强化学气相沉积系统及其紫外探测器的应用

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

锗通过原子层沉积钙钛矿型钛酸锶的外延生长

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LAO thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. Although electrostatic mechanisms have been proposed in the past to describe the existence of this critical thickness, the importance of chemical defects has been recently accentuated. Here, we describe the growth of metal/LAO/STO heterostructures in an ultra-high vacuum (UHV) cluster system combining pulsed laser deposition (to grow the LAO), magnetron sputtering (to grow the metal) and X-ray photoelectron spectroscopy (XPS). We study step by step the formation and evolution of the q2DES and the chemical interactions that occur between the metal and the LAO/STO. Additionally, magnetotransport experiments elucidate on the transport and electronic properties of the q2DES. This systematic work not only demonstrates a way to study the electrostatic and chemical interplay between the q2DES and its environment, but also unlocks the possibility to couple multifunctional capping layers with the rich physics observed in two-dimensional electron systems, allowing the fabrication of new types of devices.

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

We fabricate metal/LaAlO3/SrTiO3 heterostructures using a combination of pulsed laser deposition and in situ magnetron sputtering. Through magnetotransport and in situ X-ray photoelectron spectroscopy experiments, we investigate the interplay between electrostatic and chemical phenomena of the quasi two-dimensional electron gas formed in this system.

金属/LaAlO 的生长和静电/化学性质3/SrTiO3异

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide ...

Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 &#176;C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications.
In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

Here, we present a protocol for the synthesis of porous barium titanate (BaTiO3) thin film by a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles are used as an organic template.

孔隙诱导应变法合成多孔钛酸钡薄膜及铁电相热稳定性

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its ...

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

复合金属氧化物纳米粒子的熔融盐合成

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. ...

Metal Oxide Heterojunction for Photocatalytic Activities

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale applications. Sol-gel-based solution combustion synthesis (SG-SCS) is a simple method to produce ordered porous materials. In this regard, Pearson&#39;s hard and soft acids and bases theory assists in selecting host-dopant reactivity to form a proper heterojunction.
The formation of a heterojunction also changes the essential properties of the materials, improving photocatalysis via charge transfer or synergistic activities. A calcination temperature of 500 &#176;C is ideal for this process based on the results of the stability assessment via a differential thermogravimetry ratio analysis (DTG).
The nanoscale dimensions of the nanoparticles (NPs) and nanocomposites (NCs) generated were validated using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). Furthermore, the scanning electron microscopy micrographs and BET analyses confirmed the porosity nature of the materials. HRTEM, X-ray photoelectron spectroscopy, and energy-dispersive X-ray investigations established the materials composition. The study found that NCs degraded the acid orange 8 (AO8) color more efficiently than bare ZnO.

<meta charset="utf8"></head><body>用于光催化活性的金属氧化物异质结

The development of a heterojunction boosts the photocatalytic activities of solution combustion synthesis, which is a time-/energy-efficient process. Advanced analytical characterization techniques were used in this protocol to evaluate the materials&#39; characteristics, and nanocomposites demonstrated improved acid orange-8 dye degradation.

组分变熵稳定氧化物的体积和薄膜合成

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