SnSxSe2-x单晶纳米片的可控制备与表征

锡二硫族化合物可以通过改变硫和硒的含量来连续调控三元合金材料的带隙、载流子浓度等物理化学性质,在电子和光电子器件应用上具有巨大的潜力。本文采用化学气相沉积(CVD)技术可控地制备了不同元素组分的SnS_xSe_2-x(x=0,0.2,0.5,0.8,1.0,1.2,1.5,1.8,2.0)单晶纳米片。采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、能量色散X射线光谱(EDS)、透射电子显微镜(TEM)以及拉曼光谱等手段对SnS_xSe_2-x纳米片进行了综合表征。结果表明本方法成功实现了元素百分比可调的SnS_xSe_2-x单晶纳米片的可控制备。重点研究了依赖于元素百分比的SnS_xSe_2-x的拉曼特征谱,实验结果与基于密度泛函理论(DFT)的第一性原理计算得到的SnS_xSe_2-x的拉曼仿真谱高度吻合,理论计算结果较好地诠释了实验拉曼光谱发生变化的原因。本研究提供了一种元素百分比可调的三元SnS_xSe_2-x单晶纳米片的可控制备方法,同时对锡二硫族化合物的明确、无损识别提供了方案。     

单层MXene纳米片Ti2N电磁特性的过渡金属(Sc、V、Zr)掺杂效应

二维材料MXene纳米片由于具有较大的比表面积和较高的电子迁移率而受到广泛的关注。本文采用基于密度泛函理论的第一性原理计算,对单层MXene纳米片Ti₂N电磁特性的过渡金属(Sc、V、Zr)掺杂效应进行了系统研究。结果表明,所有过渡金属掺杂体系结合能均为负值,结构均稳定;其中Ti₂N-Sc体系的形成能为-2.242 eV,结构更易形成,且保持稳定;掺杂后Ti₂N-Sc、Ti₂N-Zr体系磁矩增大;此外,Ti₂N-Sc体系中保留了较高的自旋极化率,达到84.9%,可预测该体系在自旋电子学中具有潜在的应用价值。     

陶瓷基功能材料载体纤维增强效果及机理

以陶瓷基功能材料载体为研究对象,按照其生产工艺配方,研究了纤维种类(莫来石、氧化铝、氧化锆)及其添加量对陶瓷基功能材料载体性能的影响.在相同实验条件且不影响其功能化参数前提下,将其与未添加纤维的空白试样力学性能进行对比.结果表明,试样经1200℃烧成后,相比莫来石与氧化铝纤维增强的陶瓷基功能材料载体,氧化锆纤维的增强效果最好.当氧化锆纤维的添加量为0.8 wt;时,试样的吸水率和气孔率均较低,分别为2.0;、4.0;,相比空白对比试样抗折强度增强了42.4;.     

基于NiCo2O4纳米片电极的非对称混合电容器

The looming global energy crisis and ever-increasing energy demands have catalyzed the development of renewable energy storage systems. In this regard, supercapacitors (SCs) have attracted widespread attention because of their advantageous attributes such as high power density, excellent cycle stability, and environmental friendliness. However, SCs exhibit low energy density and it is important to optimize electrode materials to improve the overall performance of these devices. Among the various electrode materials available, spinel nickel cobaltate (NiCo₂O₄) is particularly interesting because of its excellent theoretical capacitance. Based on the understanding that the performances of the electrode materials strongly depend on their morphologies and structures, in this study, we successfully synthesized NiCo₂O₄ nanosheets on Ni foam via a simple hydrothermal route followed by calcination. The structures and morphologies of the as-synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller (BET) surface area analysis, and the results showed that they were uniformly distributed on the Ni foam support. The surface chemical states of the elements in the samples were identified by X-ray photoelectron spectroscopy. The as-synthesized NiCo₂O₄ products were then tested as cathode materials for supercapacitors in a traditional three-electrode system. The electrochemical performances of the NiCo₂O₄ electrode materials were studied and the area capacitance was found to be 1.26 C·cm^-2 at a current density of 1 mA·cm^-2. Furthermore, outstanding cycling stability with 97.6% retention of the initial discharge capacitance after 10000 cycles and excellent rate performance (67.5% capacitance retention with the current density from 1 to 14 mA·cm^-2) were achieved. It was found that the Ni foam supporting the NiCo₂O₄ nanosheets increased the conductivity of the electrode materials. However, it is worth noting that the contribution of nickel foam to the areal capacitance of the electrode materials was almost zero during the charge and discharge processes. To further investigate the practical application of the as-synthesized NiCo₂O₄ nanosheets-based electrode, a device was assembled with the as-prepared samples as the positive electrode and active carbon (AC) as the negative electrode. The assembled supercapacitor showed energy densities of 0.14 and 0.09 Wh·cm^-3 at 1.56 and 4.5 W·cm^-3, respectively. Furthermore, it was able to maintain 95% of its initial specific capacitance after 10000 cycles. The excellent electrochemical performance of the NiCo₂O₄ nanosheets could be ascribed to their unique spatial structure composed of interconnected ultrathin nanosheets, which facilitated electron transportation and ion penetration, suggesting their potential applications as electrode materials for high performance supercapacitors. The present synthetic route can be extended to other ternary transition metal oxides/sulfides for future energy storage devices and systems.     

烧结温度对Cao.9(NaCe)0.05Bi2Nb2O9无铅压电陶瓷性能的影响

采用传统固相反应法制备了Ca0.9(NaCe)0.05Bi2 Nb2 O9铋层状无铅压电陶瓷.采用XRD、SEM、EDS及相关电学性能测试系统表征了样品的晶体结构、断面形貌、元素组成以及介电、压电、铁电等性能,探究不同烧结温度对于陶瓷性能的影响.结果表明:当烧结温度为1150℃时,样品的晶体结构单一均匀,呈现片层状结构,致密性较好,压电常数高达17 pC/N,介电损耗仅为0.42;,居里温度为908℃,并且具有很好的温度稳定性,说明固相反应法制备的Ca0.9(NaCe)0.05Bi2Nb2O9压电陶瓷最佳烧结温度为1150℃.     

基于共面传输线的太赫兹片上系统的研究

太赫兹片上系统是将太赫兹的产生、传输和探测都集中在一个几平方厘米的基片上,线宽及间距达到微米量级,具有集成化程度高、系统尺寸小、稳定性好以及操作简便的特点,有利于与微量样品检测技术相互结合。研究采用HFSS软件对共面波导和共面带状线两种太赫兹共面传输线进行了仿真计算,通过优化传输线的宽度、长度、基底的厚度等关键几何参数确定出最佳的传输线结构;研究工作重点对太赫兹波段的共面带状线结构进行了设计和优化,实现了在介电常数很小的BCB基底上的低损耗传输。所得到的最佳结构参数为线宽及间距均为20μm,此结构为后续片上系统实物芯片的制作提供了参数依据。     

耐等离子刻蚀陶瓷的研究现状

等离子刻蚀技术是超大规模集成电路制备工艺中不可或缺加工技术.在半导体晶圆尺寸不断增大以及特征尺寸不断缩少的发展进程中,晶圆的污染问题越来越突出.而刻蚀机腔室材料作为晶圆的主要污染源之一,其耐等离子刻蚀性日益受到人们的关注.本文主要介绍耐等离子体刻蚀腔体材料的特性及目前国内外的研究与发展现状.     

CoP纳米片制备及其电催化产氢性能的研究

高稳定性的催化剂对于规模化电催化产氢起着关键的作用.因此,采用简单的方法合成CoP纳米片,其表现出优越电催化活性和稳定性. CoP纳米片采用水热法和在氩气中磷化法制备的,纳米片的厚度为100～300 nm.CoP纳米片在0.5 M H2SO4的电解质中,表现出良好的电化学产氢性能,起始过电为～75 mV,塔菲尔斜率为～39. 67 mV/decade,当电流密度为10 mA· cm-2,过电压为～125 mV,经过1000次的循环后,保持良好的稳定性能.     

HgCdTe薄膜的输运特性及其应力调控

窄禁带直接带隙半导体材料碲镉汞(Hg1–xCdxTe)是一种在红外探测与自旋轨道耦合效应基础研究方面都具有重要应用意义的材料.本文对单晶生长的体材料Hg0.851Cd0.149Te进行阳极氧化以形成表面反型层,将样品粘贴在压电陶瓷上减薄后进行磁输运测试,在压电陶瓷未加电压时观察到了明显的SdH振荡效应.对填充因子与磁场倒数进行线性拟合,获得样品反型层二维电子气的载流子浓度为ns=1.25×10^16m^-2.在不同磁场下,利用压电陶瓷对样品进行应力调控,观测到具有不同特征的现象,分析应是样品中存在二维电子气与体材料两个导电通道.零磁场下体材料主导的电阻的变化应来源于应力导致的带隙的改变;而高场下产生类振荡现象的原因应为应力导致的二维电子气能级的分裂.