生理盐水在经济上得到了日本促进科学促进会 (KAKENHI) 资助的资助 (26810126 号赠款)。黄感谢 Deanship 的科学研究, 通过科研椅副 Deanship 创建。
在纳米加工设备上进行了广角 XRD 测量, 由日本国家高级工业科学技术研究院 (AIST) (IBEC) 创新平台共同提供支持。堀场技术服务有限公司和日本材料科学技术促进基金会 (MST) 分别进行了多孔薄膜的拉曼光谱测量和透射电镜观察。MST 还对透射电镜图像中的应变进行了可视化。我们感谢 Edanz 集团 (www.edanzediting.com/ac) 博士的安德鲁. 杰克逊编辑这篇手稿的草稿。

1. 前体溶液的制备
<ol><li>溶出50毫克的两嵌段共聚物 PS (18000)-b-聚氧乙烯 (7500) 在1.5 毫升的四氢呋喃在40°c。冷却聚合物溶液室温 (RT)。</li>
	<li>将127.7 毫克醋酸钡溶于830µL 乙酸, 搅拌40摄氏度, 5 分钟. 将醋酸钡溶液冷却到 RT 中. 添加170毫克钛丁醇到醋酸钡溶液中, 搅拌反应混合物1分钟。</li>
	<li>将聚合物溶液加入醋酸钡溶液滴状。</li>
</ol>2. 介孔钛酸钡薄膜的合成
<ol><li>在自旋涂布机的舞台上设置 Si/x 型 x-/Ti/铂基板 (2 厘米 x 2 厘米), 并将准备好的前体溶液放在完全覆盖基体上。 注:x、Ti 和 Pt 层的薄膜厚度分别约为1.6、40和 150 nm。</li>
	<li>以 500 rpm 为5秒 (第一步), 然后依次为三十年代 (第二步) 的 3000 rpm 旋转 Si/正向x/Ti/Pt 衬底。</li>
	<li>将准备好的薄膜放在热板上, 加热到120摄氏度, 使其老化5分钟, 然后让它自然冷却室温 (RT)。</li>
	<li>将退火后的薄膜放在消音器炉内, 在空气中煅烧800摄氏度, 10 分钟, 斜坡速度为1摄氏度/分钟 (用于加热和冷却)。</li>
</ol>3. 表征
<ol><li>形态学和晶体表征
	<ol>
<li>
扫描电镜 (SEM) 测量
		<ol>
<li>把样品放在样品台上, 用碳胶带覆盖边角以修复样品。调整样品持有者的高度。</li>
			<li>将样品持有者设置在装货杆中, 并将其插入扫描电镜. 将样品持有者放置在工作距离为8毫米的家庭位置。</li>
			<li>将加速电压和发射电流设置为5伏和10毫安, 并生成电子束。在低放大率下显示示例的整个图像。移动舞台以显示感兴趣的区域 (ROI), 并将焦点放在图像上。</li>
			<li>将放大倍数提高到50,000X。关注毛孔, 观察多孔形态。当观察到合适的图像时, 保存图片。</li>
		</ol>
</li>
		<li>
透射电镜 (TEM) 测量
		<ol>
<li>按照步骤3.3.1 中的描述, 在 TEM 测量之前准备一个截面试样。</li>
			<li>在样品架上设置准备好的标本。将加速电压设置为300伏并生成电子束。将持有者插入 TEM。</li>
			<li>在低放大率下显示示例的整个图像。移动舞台以显示 ROI 并聚焦于图像。</li>
			<li>将放大倍数提高到250,000X。着重于样品, 观察合成薄膜的多孔形貌 (~200 纳米厚度)。当观察到合适的图像时, 保存图片。</li>
		</ol>
</li>
		<li>
广角 X 射线衍射 (XRD) 测量
		<ol>
<li>设置装有铜 Kα源的 x 射线衍射仪。</li>
			<li>把样品放在样品台上的中心。</li>
			<li>调整示例在其中阻止 X 射线的一半的 Z 轴 (i. e, 高度位置)。然后, 调整ω轴 (i. e, 放牧角度), 使样品表面平行于 X 射线。</li>
			<li>重复步骤 3.1.3.3, 直到采样阶段位置变得合适 (i. e), 样品表面位于 x 射线光束的中心, 并与 x 射线平行。</li>
			<li>将ω固定到一个小角度 (e. g, 0.5°), 然后将 2θ (i. e, 探测器角度) 从扫描到 70°, 其速率为 1°/分钟. 在测量后保存数据。 注: 为了抑制衬底上的背景信号, 在一个非常小的掠角照射到合成薄膜的表面时, 进入的 X 射线被辐照。</li>
		</ol>
</li>
	</ol></li>
	<li>铁电相热稳定性试验
	<ol>
<li>打开拉曼显微镜和操作计算机, 然后打开操作软件 LabSpec。单击自动校准以校准计算机。</li>
		<li>在加热阶段设置玻璃滑块, 然后将合成膜放在玻璃上。关闭舞台的封面。</li>
		<li>使用15°c/分钟的坡道比加热阶段来加热样品。当温度达到目标温度时, 设置加热阶段以保持温度, 等待几分钟。 注: 在本研究中, 我们选择了 RT 和 50, 75, 100, 110, 120, 125, 130, 135, 140, 和150°c 为散装 BT, 其中居里温度约130°c。我们选择了 RT 的温度和 75, 125, 175, 225, 275, 325, 375, 425, 475, 和525摄氏度为介孔 BT 薄膜, 居里温度被评估是大约470°c 从早先研究8。</li>
		<li>在温度稳定后, 用共焦拉曼显微镜测量不同温度下的拉曼光谱, 使用300µm 共焦孔和 532 nm 激光器 (样品10兆瓦) 进行励磁。单击视频图标以显示所观察到的图像, 然后将焦点放在图像上。分别将采集时间和累计设置为100s 和 3, 然后单击度量图标以开始测量。在测量后保存数据。</li>
		<li>继续测量直到频谱发生变化 (i. e, 可分配到铁电相的峰值消失)。 注: 测量值为三点, 得到的光谱平均值。</li>
	</ol></li>
	<li>应变的可视化
	<ol>
<li>用聚焦离子束对外周铣、底、微桥切割、试样细化等微抽样方法制备出合成薄膜中的横断面试样。试样的尺寸应约为20µm 长度和4µm 的厚度。</li>
		<li>测量高分辨率透射电镜 (2,000,000X) 在凸和凹面引起的孔隙度。</li>
		<li>选择一个面积 (512 x 512 像素) 的快速傅立叶变换 (fft), 并计算 fft 模式。从 FFT 模式估计晶格间距, 并将其除以无应变晶格间距, 计算出 "变形比"。</li>
		<li>将 FFT 分析区域移动32像素, 然后重复步骤3.3.3。继续这个过程, 直到所有的 HR-TEM 图像覆盖面积 (在本研究中, 5664 x 5664 像素 (162 x 162 点))。 注: 从最小失真的 FFT 图像估计无应变晶格间距。</li>
		<li>根据计算的变形比设置区域的颜色, 以可视化应变。通过计算变形比来制作直方图。 注: 通过软件 CryStMapp, 对 HR 图像的变形进行了分析。</li>
		<li>
创建一个详细的直方图使用软件伊戈尔 Pro 注: 由于步骤3.3.5 中获得的失真直方图是粗糙的, 因此创建了一个使用软件伊戈尔 Pro 的详细直方图。<ol>
<li>通过选择数据 |装载波浪 |加载常规文本并将其另存为波形且名称正确。 注意: 伊戈尔 Pro 定义的对象, 包括一个数字数组作为一个波。</li>
			<li>通过选择数据 | 将保存的波形更改为矩阵 (162 x 162) 更改波形缩放。</li>
			<li>通过选择图像 | 将波形显示为2D 图像|新 |图像端口。</li>
			<li>选择分析 |包装 |图像处理以显示图像菜单。</li>
			<li>选择图像 |roi显示 roi 面板。选择启动 roi 绘制以选择 roi。在图像的顶部绘制区域, 然后选择完成 ROI。</li>
			<li>选择保存 ROI 副本以创建掩码以选择要作为 ROI_M_Mask 波形分析的区域。</li>
			<li>在命令窗口的命令行中输入 "ImageHistogram = M_ROIMASK/秒waveneame" 以制作直方图。在 wavename 中使用步骤3.3.6.1 中设置的名称。</li>
			<li>在命令窗口的命令行中输入 "显示 W_ImageHist" 以显示直方图。如果需要, 修改图表。</li>
		</ol>
</li>
	</ol></li>
</ol>

<ol>
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作者没有什么可透露的。

在多孔 BT 薄膜 (图 3b) 的拉曼光谱中, A1(to) 模式的分裂来源于压缩应变。FFTM 方法 (图 4) 清楚地观察到了这个特性, 并且它在 [1-10] 方向上的各向异性都是从失真的直方图 (图 5) 中确定的。沿 [1-10] 方向的压缩应变与诱导 (001) 表面的双向压缩应变具有相似的效果, 增强了 BT1中的铁电性。多孔驱动的各向异性应变拉长晶格向c轴的方向, 导致 Ti4 +的进一步错位从晶格中心。这种位错预计会增加电偶极矩, 进而增强其铁 (压电) 电流。事实上, 介孔 BT 薄膜的压电性优于非多孔膜8。
在 BT 晶格中诱导的应变稳定了畸变的四方相。因此, 晶格的热稳定性有望得到增强。多孔 BT 薄膜的拉曼光谱表明, 四方相起源峰 (在710厘米−1) 保持可见, 直到375摄氏度, 虽然峰值逐渐变弱和更宽 (图 6b)。这种趋势类似于以前的研究中发现的情况, 其中Tc估计为470°c8。因此, 我们证实了在 BT 薄膜中的孔隙驱动应变有效地热稳定四方相的假设。
通过这项研究, 我们澄清了由一个简单而廉价的化学程序形成的孔隙诱导应变与由晶格不匹配引起的异质界面的应变有相似的影响。这些发现为应变工程提供了新的见解。

钛酸钡 (BaTiO3, 此后 BT) 是典型的钙钛矿型铁电材料。尽管其铁电性质在二十世纪四十年代被发现, 但由于其良好的铁电和压电反应以及良好的介电常数, 至今仍被广泛应用。此外, 由于 BT 是一种无铅, 环保的材料, 它已吸引了极大的兴趣, 以取代锆钛酸铅 (PZT)。在室温下, BT 的晶体相位为四方, 其中c和晶格参数 ( c/a) 的比率不等于1。在四方阶段, BT 晶格稍微拉长向c轴和阳离子 (Ba2 +, Ti4 +) 和阴离子 (O2−) 在相反方向偏移。这种位移导致 BT 的自发极化. 当温度上升到居里温度 (Tc) 时, 会发生相变到立方相。在 BT 的立方相, 它有c/a = 1, 晶格畸变是宽松的, 并且它的铁电性丢失由于电子中立地位起源于晶格的反演对称。近年来, 高温铁电材料的使用已经扩大。但是, bt 的Tc相对较低 (~130 °c), 而大宗 bt 不满足这些要求。
为了增加 BT 的Tc , 铁电 (四方) 相通过在异质界面上的应变的应用而得到稳定。例如, 崔et增强了外延定向生长在GdScO 3 (110) 和DyScO 3 (110) 基板上生长的 BT 薄膜的铁电性, 通过使用晶格不匹配1引起的双轴压缩应变。但是, Tc的增加仅限于非常薄的薄膜 (十纳米厚)2,3, 这对于设备应用程序来说是不切实际的。
为了提高 BT 膜厚度, 同时防止应变松弛, 开发了超晶格 (非常薄层的周期结构) 和三维 (3D) 的异纳米构造。哈林顿et合成了 BT 和 Sm2O3的垂直细观结构, 并获得了一微米级有序厚膜, 不需要应变松弛。在本例中, 由于 BT 单元细胞的单轴扩张, 自发极化取向与基底垂直;因此, 在高温下保持了大量的残余极化 (i. e, Tc大于800°c)4。所得性能满意;然而, 制造过程中需要一个复杂而昂贵的物理流程 (脉冲激光沉积), 这是实际应用的一个缺点。
作为一种替代性的简便和廉价的制造工艺, 我们提出了3D 纳米复合材料的化学合成, 通过引入一个前体溶液的 BT 成孔隙的多孔钛酸锶 (SrTiO3, 此后 ST) 薄膜5.本研究采用表面活性剂辅助溶胶-凝胶法制备了多孔 ST 薄膜, 其中双亲表面活性剂胶束自组装为有机模板6,7。该方法在图 1中以示意图的方式说明。由于所获得的 ST 薄膜具有复杂的3D 多孔结构, 具有较大的表面积, 因此将 bt/ST 异质界面上的应变引入到纳米复合材料中, 从而导致 bt 铁电相位的稳定化 ( Tc ST/BT 纳米复合材料达到230摄氏度)。
假设孔隙度可以直接引入 BT 的应变, 提高铁电性质的热稳定性。本研究采用表面活性剂辅助溶胶-凝胶法制备多孔 BT 材料, 并对孔隙诱导菌株进行检查。此外, 我们还比较了多孔 bt 和型无孔散 bt 的热稳定性. 我们发现, 引入的孔隙诱导了各向异性的应变, 延长了 bt 晶格。这种效应可能有利于稳定铁电相。因为这里使用的合成过程非常简单, 它比传统的物理过程对3D 异质纳米结构有优势。

<table>
	<tbody>
		<tr>
			<td>Diblock Copolymer PS(18000)-b-PEO(7500)</td>
			<td>Polymer Source, Inc.</td>
			<td>#8399-SEO</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic acid (37 wt.%)</td>
			<td>Wako</td>
			<td>017-00256</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrahydrofuran</td>
			<td>Wako</td>
			<td>204-08745</td>
			<td></td>
		</tr>
		<tr>
			<td>Barium acetate</td>
			<td>Sigma-Aldrich</td>
			<td>243671-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Titanium(IV) butoxide</td>
			<td>Sigma-Aldrich</td>
			<td>244112-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Reference bulk BT single crystal</td>
			<td>Crystal Base Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Balance</td>
			<td>Sartorius</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hot stirrer</td>
			<td>IKA</td>
			<td>RCT basic</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin coater</td>
			<td>Active</td>
			<td>ACT-300DII</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot plate</td>
			<td>As one</td>
			<td>ND-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Muffle Furnace</td>
			<td>Yamato Scientific Co., Ltd.</td>
			<td>FO series</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning electron microscopy</td>
			<td>Hitachi</td>
			<td>SU-8000</td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission electron microscopy</td>
			<td>Hitachi</td>
			<td>H-9000NAR</td>
			<td></td>
		</tr>
		<tr>
			<td>Wide-angle X-ray diffraction</td>
			<td>Rigaku</td>
			<td>RINT-Ultima III</td>
			<td></td>
		</tr>
		<tr>
			<td>Raman microscope</td>
			<td>Horiba</td>
			<td>XploRA Plus</td>
			<td></td>
		</tr>
	</tbody>
</table>

chemical synthesis of porous barium titanate thin film and thermal stabilization of ferroelectric phase by porosity-induced strain

钛酸钡 (BaTiO3, 此后 BT) 是二十世纪四十年代首次发现的铁电材料, 由于其平衡的铁电性、压电和介电常数, 它仍然被广泛使用。此外, BT 不含任何有毒成分。因此, 它被认为是一种生态友好的材料, 这已引起了相当大的兴趣作为替代锆钛酸铅 (PZT)。然而, 散装 BT 丢失它的铁电性在大约130°c, 因此, 它不可能在高温使用。由于对高温铁电材料的需求量越来越大, 提高铁电性在 BT 中的热稳定性具有重要的意义. 在前人研究中, 采用了基于异质界面晶格失配的应变。然而, 这种方法的样品准备需要复杂而昂贵的物理过程, 这是不可取的实际应用。
在本研究中, 我们提出了一种化学合成的多孔材料作为一种替代方法引入应变。采用表面活性剂辅助溶胶-凝胶法制备了多孔 BT 薄膜, 采用自组装双亲表面活性剂胶束作为有机模板。通过一系列的研究, 我们阐明了孔隙的引入对 BT 晶格的畸变具有类似的作用, 对异质界面的影响, 导致了铁电性的增强和稳定。由于其简单性和成本效益, 这一制造过程比传统方法有相当大的优势。

用电子显微镜对所获得的介孔 BT 薄膜的形貌进行了研究。一个顶级的 SEM 图像证实了合成 BT 薄膜的多孔特性 (图 2a)。用横断面 TEM 图像 (图 2b) 研究了深度方向的形态学特征。直径为几纳米的大晶粒垂直堆积, 这些晶粒之间的空隙是孔隙。估计的 BT 薄膜厚度约为200纳米。
采用广角 XRD 测量方法研究了 BT 骨架的结晶度。BaCO3和2的非常微弱的峰值是可检测的, 并清楚地观察到了可以分配给 BT 晶体的突出峰值 (图 3a)。然而, 很难区分 (铁电) 四方和 (顺电) 立方相。这是因为两个阶段的 XRD 模式相当相似。主要区别在于, 三次相的2个θ = 45°的峰值为四方相分裂。在这项研究中, 由于薄膜的多晶性质拓宽了峰值宽度, 所以这种分裂的检测是困难的。因此, 为了澄清薄膜的晶相, 测量了其拉曼光谱 (图 3b)。在室温下, 大体积单 BT 晶体的拉曼光谱显示峰中心为 275, 305、515和 720 cm−1, 它被分配给a1(to), B1+e(到 + LO), e(到) +a1(to) 和E(lo) +A1(四方) 模式, 该阶段9。在多孔 BT 薄膜的频谱中, 尽管发生了A1(to) 模式的分裂, 但频谱的主要特征仍然保留。从而四方了合成多孔 BT 薄膜。
用快速傅里叶变换映射 (FFTM) 方法10检验了薄膜 BT 框架中应变的空间分布。该方法对高分辨率 (HR) TEM 图像 FFT 模式的微小畸变进行了分析和可视化。图 4描述了具有凸和凹面的薄膜区域的 HR TEM 图像以及相应的 FFTM 图像。凸区 [1-10] 方向的 FFTM 图像表明, 最外层凸面略有扩张, 这一安排应引起晶格松弛, 减弱铁电性。相反, 在表面下方的区域被压缩, 并且压缩的区域在框架之内完全地被观察了。这一结果与以前的报告一致, 表明 BT 纳米粒子的表面具有顺电立方相, 而内芯是铁电四方相 11, 12.在 BT 框架内, 还发现了一些扩展的区域, 主要是在缺陷和/或晶界 (图 4c) 中。对于凹区, 虽然最外层表面的变形没有被清楚地观察到, 很可能是因为曲面是多边形而不是弯曲的, 所以检测到框架内的压缩 (图 4d)。相反, 凸和凹区域的 [11-1] 方向的 FFTM 图像不清楚 (图 4e, f), 这表明 BT 单元细胞在这个方向上的变形不大。
为了更定量地考察 BT 晶格的变形程度, 在直方图 (图 5) 中总结了变形度。从这些直方图中, 我们确定了 "变形比", 它被定义为在目标和参照区域中相邻晶格间距之间的距离, 作为变形的度量。在 [11-1] 方向上, 直方图以1.00 的变形比为中心, 在凸和凹区域上几乎是对称的。这一结果表明, [11-1] 方向的应变很少, 与上面提到的 FFTM 结果一致。反之, [1-10] 方向的直方图中包含有显著的峰值, 变形率约为 0.99, 显示了 BT 薄膜中压缩应变增加的区域。
从温度依赖性的拉曼光谱 (图 6) 考察了铁电四方相的热稳定性。在大容量 bt 单晶中, 305 和720厘米−1的尖峰消失在140摄氏度, 这与大容量 bt (~ 130 °c) 的TC 一致。反之, 在710厘米−1从四方阶段的峰值保持在更高的温度, 可检测到高达375摄氏度的合成多孔薄膜。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57441/57441fig1.jpg"> 图 1: 表面活性剂辅助溶胶-凝胶法的示意图图象.采用双亲表面活性剂胶束自组装为模板。结合有机模板和无机溶胶, 建立了有机/无机混合体。最后, 通过去除有机模板, 结晶无机骨架, 进行煅烧, 形成孔隙。<a href="https://cloudflare.jove.com/files/ftp_upload/57441/57441fig1large.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/57441/57441fig2v3.jpg"> 图 2: 介孔 BT 薄膜的电子显微镜图像.(a) 顶部查看 SEM 和 (b) 横断面 TEM 图像。这一数字已从铃木, N.等等中修改。13按照 "创作共享" 属性 (CC) 许可证进行。<a href="https://cloudflare.jove.com/files/ftp_upload/57441/57441fig2v3large.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/57441/57441fig3.jpg"> 图 3: 介孔 BT 薄膜晶体相的光谱数据.(a) 宽角度 XRD 模式和 (b) 在室温下合成的多孔 BT 薄膜的拉曼光谱。同时还包括了大量 BT 单晶的光谱。这一数字已从铃木, N.等等中修改。13按照 "创作共享" 属性 (CC) 许可证进行。<a href="https://cloudflare.jove.com/files/ftp_upload/57441/57441fig3large.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/57441/57441fig4v2.jpg"> 图 4: 孔隙诱导应变的可视化.(a, b)高分辨率 TEM 图像和 (c f) 快速傅立叶变换映射 (FFTM) 图像 (a、c、e) 凸和 (b、d、f) 的 BT 薄膜凹区。FFTM 图像的方向为 (c、d) [1-10] 和 (e、f) [11-1]。在 FFTM 图像中, 绿色和红色区域代表分别应用压缩和拉伸应变的区域, 而黄色表示参照区域。用于分析的方向也包括 (左)。这一数字已从铃木, N.等等中修改。13按照 "创作共享" 属性 (CC) 许可证进行。<a href="https://cloudflare.jove.com/files/ftp_upload/57441/57441fig4v2large.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/57441/57441fig5.jpg"> 图 5: 孔隙诱导应变的分析.失真直方图分析 (a) 凸 (图 4a,图 4c,图 4e) 和 (b) 凹 (图 4b,图 4d,图 4f) 多孔 BT 薄膜的区域. 此数字已根据 "创作共享" 归属 (CC) 许可证, 从铃木、N. et . 13 修改。<a href="https://cloudflare.jove.com/files/ftp_upload/57441/57441fig5large.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/57441/57441fig6.jpg"> 图 6: 铁电相的热稳定性.温度依赖性的拉曼光谱 (a) 的大容量 bt 单晶和 (b) 合成多孔 bt 薄膜。这一数字已从铃木, N.等等中修改。13根据 "创作共享" 属性 (CC) 许可证.  <a href="https://cloudflare.jove.com/files/ftp_upload/57441/57441fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain at JoVE.com

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

在这里, 我们提出了一个通过表面活性剂辅助溶胶-凝胶法合成多孔钛酸钡 (BaTiO3) 薄膜的协议, 其中自组装双亲表面活性剂胶束用作有机模板。

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 ...

chemical-synthesis-porous-barium-titanate-thin-film-thermal

Research

JoVE Journal

Chemistry

10.9K 次观看.  Tokyo University of Science (TUS). 在这里, 我们提出了一个通过表面活性剂辅助溶胶-凝胶法合成多孔钛酸钡 (BaTiO3) 薄膜的协议, 其中自组装双亲表面活性剂胶束用作有机模板。

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

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography

The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. Diiodomethyllithium is prepared by the deprotonation of diiodomethane with LiHMDS, in a THF/diethyl ether mixture, at -78 &#176;C in the dark. These conditions are essential for the stability of the LiCHI2 reagent generated. The subsequent dropwise addition of N-Ts aldimines to the preformed diiodomethyllithium solution affords an amino-diiodide intermediate, which is not isolated. Rapid warming of the reaction mixture to 0 &#176;C promotes cyclization to afford iodoaziridines with exclusive cis-diastereoselectivity. The addition and cyclization stages of the reaction are mediated in one reaction flask by careful temperature control.
Due to the sensitivity of the iodoaziridines to purification, assessment of suitable methods of purification is required. A protocol to assess the stability of sensitive compounds to stationary phases for column chromatography is described. This method is suitable to apply to new iodoaziridines, or other potentially sensitive novel compounds. Consequently this method may find application in range of synthetic projects. The procedure involves firstly the assessment of the reaction yield, prior to purification, by 1H NMR spectroscopy with comparison to an internal standard. Portions of impure product mixture are then exposed to slurries of various stationary phases appropriate for chromatography, in a solvent system suitable as the eluent in flash chromatography. After stirring for 30 min to mimic chromatography, followed by filtering, the samples are analyzed by 1H NMR spectroscopy. Calculated yields for each stationary phase are then compared to that initially obtained from the crude reaction mixture. The results obtained provide a quantitative assessment of the stability of the compound to the different stationary phases; hence the optimal can be selected. The choice of basic alumina, modified to activity IV, as a suitable stationary phase has allowed isolation of certain iodoaziridines in excellent yield and purity.

A protocol for the diastereoselective one-pot preparation of cis-N-Ts-iodoaziridines is described. The generation of diiodomethyllithium, addition to N-Ts aldimines and cyclization of the amino gem-diiodide intermediate to iodoaziridines is demonstrated. Also included is a protocol to rapidly and quantitatively assess the most appropriate stationary phase for purification by chromatography.

合成和Iodoaziridines纯化涉及定量选择最优固定相的色谱

The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. ...

科研

化学

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

对磷酸增强富集制备高度多孔配位聚合物涂层的孔聚合物石柱的

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form catalytically active N-Heterocyclic Carbenes (NHCs). Here we have used ILs as precatalysts in the addition of &#945;,&#946;-unsaturated aldehydes to chalcones to form 1,6-ketoesters, incorporating an anti-diphenyl moiety in a highly stereoselective fashion. The reaction has a broad substrate scope and several functional groups and heteroaromatics can be integrated into the ketoester backbone in generally good yields with maintained stereoselectivity. The reaction protocol is robust and scalable. The starting materials are inexpensive and the products can be obtained after simple filtration, avoiding solvent-demanding chromatography. Furthermore, the IL can be recycled up to 5 times without any loss of reactivity. Moreover, the 1,6-ketoester end product is a potent gelator in several hydrocarbon based solvents. The method enables rapid access to and evaluation of a new class of low molecular weight gelators (LMWGs) from recyclable and inexpensive starting materials.

Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.

1,6-酮酯高立体选择性合成离子液体介导:三组分反应启用快速进入低分子量胶凝剂的新型类

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150&#160;nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m2g-1, which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide.

The surfactant mediated sol-gel synthesis of nanosized monosodium titanate is described, along with preparation of the corresponding peroxide modified material. An ion-exchange reaction with Au(III) is also presented.

纳米尺寸钛酸二氢钠的合成和化学反应

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

超分子胶体的合成与表征

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

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 ...

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

We detail the synthesis and purification of a mitochondrial calcium uptake inhibitor, [(OH2)(NH3)4Ru(&#181;-O)Ru(NH3)4(OH2)]5+. The optimized synthesis of this compound commences from [Ru(NH3)5Cl]Cl2 in 1 M NH4OH in a closed container, yielding a green solution. Purification is accomplished with cation-exchange chromatography. This compound is characterized and verified to be pure by UV-vis and IR spectroscopy. The mitochondrial calcium uptake inhibitory properties are assessed in permeabilized HeLa cells by fluorescence spectroscopy.

A protocol for the synthesis, purification, and characterization of a ruthenium-based inhibitor of mitochondrial calcium uptake is presented. A procedure to evaluate its efficacy in permeabilized mammalian cells is demonstrated.

钌线粒体钙吸收抑制剂的合成与评价

We detail the synthesis and purification of a mitochondrial calcium uptake inhibitor, [(OH2)(NH3)4Ru(&#181;-O)Ru(NH3)4(OH2)]5+. The optimized synthesis of ...

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of solid-phase synthesis, regenerating Michael (REM) linker strategies, and 1,3-dipolar cycloaddition, a library of structurally similar heterocycles, both with and without a spirocyclic center, can be constructed. The main advantages of the solid-support synthesis are as follows: first, each reaction step can be driven to completion using a large excess of reagents resulting in high yields; next, the use of commercially available starting materials and reagents keep the costs low; finally, the reaction steps are easy to purify via simple filtration. The REM linker strategy is attractive because of its recyclability and traceless nature. Once a reaction scheme is completed, the linker can be reused multiple times. In a typical solid-phase synthesis, the product contains either a part of or the whole linker, which can prove undesirable. The REM linker is &#34;traceless&#34; and the point of attachment between the product and the polymer is indistinguishable. The high diastereoselectivity of the intramolecular 1,3-dipolar cycloaddition is well documented. Limited by the insolubility of the solid support, the reaction progression can only be monitored by a change in the functional groups (if any) via infrared (IR) spectroscopy. Thus, the structural identification of intermediates cannot be characterized by conventional nuclear magnetic resonance (NMR) spectroscopy. Other limitations to this method stem from the compatibilities of the polymer/linker to the desired chemical reaction scheme. Herein we report a protocol that allows for the convenient production of spirocyclic heterocycles that, with simple modifications, can be automated with high-throughput techniques.

Here we present a protocol to demonstrate an efficient method for the synthesis of spirocyclic heterocycles. The five-step process utilizes solid-phase synthesis and regenerating Michael linker strategies. Generally difficult to synthesize, we present a customizable method for the synthesis of spirocyclic molecules otherwise inaccessible to other modern approaches.

[4.4] 刺环氧基的固相合成

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of ...

Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries of the metal. Using this method, a crack free, thin-film macroelectrode surface with up to 40 times increase in active surface area was obtained. The roughening is easy to do in a standard electrochemical characterization laboratory and incudes the application of voltage pulses followed by extended application of a reductive voltage in a perchloric acid solution. The protocol includes the chemical and electrochemical preparation of both a macroscale (1.2 mm diameter) and microscale (20 &#181;m diameter) platinum disc electrode surface, roughening the electrode surface and characterizing the effects of surface roughening on electrode active surface area. This electrochemical characterization includes cyclic voltammetry and impedance spectroscopy and is demonstrated for both the macroelectrodes and the microelectrodes. Roughening increases electrode active surface area, decreases electrode impedance, increases platinum charge injection limits to those of titanium nitride electrodes of same geometry and improves substrates for adhesion of electrochemically deposited films.

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries. The electrochemical techniques of cyclic voltammetry and impedance spectroscopy are demonstrated to characterize these electrode surfaces.

薄膜铂金宏观和微电极的电化学粗加工

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries ...

Iron Nanowire Fabrication by Nano-Porous Anodized Aluminum and its Characterization

Magnetic nanowires possess unique properties that have attracted the interest of different fields of research, including basic physics, biomedicine, and data storage. We demonstrate a fabrication method for iron (Fe) nanowires&#160;via electrochemical deposition into anodic&#160;alumina oxide (AAO) templates. The templates are fabricated by anodization of aluminum (Al) discs, and the pore length and diameter are controlled by changing the anodizing conditions. Pores with an average diameter of around 120 nm are created using oxalic acid as the electrolyte. Using this method, cylindrical nanowires are synthesized, which are released by dissolving the alumina using a selective chemical etchant.

In this work, we describe a&#160;protocol to fabricate iron nanowires, including the formation of the porous alumina membrane that is used as the template, electrodeposition into templates using electrolyte solution, and the release of the nanowires into the solution.

纳米孔阳极氧化铝的铁纳米线制造及其特性

Magnetic nanowires possess unique properties that have attracted the interest of different fields of research, including basic physics, biomedicine, and ...