Interlayer Engineering of Molybdenum Trioxide toward High‐Capacity and Stable Sodium Ion Half/Full Batteries

Orthorhombic molybdenum trioxide (MoO₃) is one of the most promising anode materials for sodium‐ion batteries because of its rich chemistry associated with multiple valence states and intriguing layered structure. However, MoO₃ still suffers from the low rate capability and poor cycle induced by pulverization during de/sodiation. An ingenious two‐step synthesis strategy to fine tune the layer structure of MoO₃ targeting stable and fast sodium ionic diffusion channels is reported here. By integrating partially reduction and organic molecule intercalation methodologies, the interlayer spacing of MoO₃ is remarkably enlarged to 10.40 Å and the layer structural integration are reinforced by dimercapto groups of bismuththiol molecules. Comprehensive characterizations and density functional theory calculations prove that the intercalated bismuththiol (DMcT) molecules substantially enhanced electronic conductivity and effectively shield the electrostatic interaction between Na⁺ and the MoO₃ host by conjugated double bond, resulting in improved Na⁺ insertion/extraction kinetics. Benefiting from these features, the newly devised layered MoO₃ electrode achieves excellent long‐term cycling stability and outstanding rate performance. These achievements are of vital significance for the preparation of sodium‐ion battery anode materials with high‐rate capability and long cycling life using intercalation chemistry.     

基于压电力显微镜的铌酸锂电畴稳定性研究

研究了Z切700 nm厚的单晶铌酸锂(LiNbO₃)薄膜电畴的调控方法。利用X射线衍射仪(XRD)和原子力显微镜(AFM)对单晶LiNbO₃薄膜的晶向和形貌进行了表征,并通过外加电场对单晶LiNbO₃薄膜电畴进行调控。研究结果表明,该LiNbO₃薄膜具有单一的(006)衍射峰,表面光滑、粗糙度低(均方根粗糙度小于1 nm)。通过外加电场和预设电畴图案对LiNbO₃电畴进行精准调控,并测试了电畴稳定性。测试结果显示,调控后的电畴在温度为25~150℃内处于稳定状态,且在30 d内保持稳定,未发生弛豫现象。该研究为LiNbO₃电畴工程器件的研发和应用提供了重要的技术支撑。     

粒子群算法在BRDF模型参数优化中的应用

根据粗糙样片1.06微米激光双向反射分布函数(BRDF)的实验数据,利用粒子群算法结合BRDF五参数模型,对不同样片表面的BRDF进行了统计建模,获得了对应样片BRDF模型的参数值与偏差.获得的BRDF优化统计模型与没有参与优化建模的实验数据也吻合良好,验证了建模结果的合理性与正确性.将粒子群算法与遗传算法进行了比较,表明无论是优化计算时间还是拟合的精度,前者都明显优于后者.     

OFDM频偏信道联合估计算法

针对OFDM系统中频偏和信道联合估计问题进行了研究。为了克服单独估计的缺陷,提高精度,提出了一种低复杂度的频偏信道联合估计算法。该算法首先通过采用正交性质的恒包络零相关序列,运用最大似然法估计信道,提取频偏估计值,然后对信道结果进行修正,使之更接近真实信道。同时给出了频偏估计的克拉美罗界。仿真结果表明,相比于最小二乘联合估计法,本文算法估计均方误差更小,具有更好的估计性能。      

飞秒激光在透明介质中制备波导器件进展

飞秒激光脉冲通过非线性相互作用可以在透明介质内部诱导载流子的激发、弛豫和折射率改变,从而用于制备光波导器件。飞秒激光无法比拟的高度局域三维加工能力使其在有源和无源波导器件制备中被广泛研究。综述了飞秒激光在多种透明介质中诱导折射率改变的机理、波导器件制备的实验进展和波导性能优化技术,分析了其研究趋势和应用前景。     

基于UWB隐藏目标探测接收装置设计

基于低频电磁波对非金属介质的强穿透性和UWB脉冲信号在距离向的高分辨特性，采用超宽带（UWB）脉冲信号的低频部分实现穿墙探测的设想，研究了超宽带穿墙探测雷达的运动目标回波信号模型，根据运动物体的多普勒频移原理，探讨采用相关检测技术实现非金属墙壁后面的运动物体的检测问题。     

模糊控制理论在发动机温度控制中的应用

以模糊控制理论为基础，针对发动机温度控制中存在的非线性等问题，分析了当前发动机温度控制系统，并提出了发动机温度模糊控制方案。试验表明，采用模糊控制器后，显著改善了发动机温度自动控制的效果．     

车内声学灵敏度数值计算新方法研究

以有限元法为基础,提出一类计算车内灵敏度的方法,并对计算所得到的复数灵敏度分解为幅值灵敏度和相位灵敏度,这2种灵敏度能够分别准确反应车身结构和边界条件变化对声压幅值与相位的影响.最后在某型汽车的三维NASTRAN模型中,计算了灵敏度,并进一步计算出幅值灵敏度,计算结果验证了所提出方法的可行性.     

Layer‐Controlled and Wafer‐Scale Synthesis of Uniform and High‐Quality Graphene Films on a Polycrystalline Nickel Catalyst

Chemical vapor deposition (CVD) provides a synthesis route for large‐area and high‐quality graphene films. However, layer‐controlled synthesis remains a great challenge on polycrystalline metallic films. Here, a facile and viable synthesis of layer‐controlled and high‐quality graphene films on wafer‐scale Ni surface by the sequentially separated steps of gas carburization, hydrogen exposure, and segregation is developed. The layer numbers of graphene films with large domain sizes are controlled precisely at ambient pressure by modulating the simplified CVD process conditions and hydrogen exposure. The hydrogen exposure assisted with a Ni catalyst plays a critical role in promoting the preferential segregation through removing the carbon layers on the Ni surface and reducing carbon content in the Ni. Excellent electrical and transparent conductive performance, with a room‐temperature mobility of ≈3000 cm² V^?1 s^?1 and a sheet resistance as low as ≈100 Ω per square at ≈90% transmittance, of the twisted few‐layer grapheme films grown on the Ni catalyst is demonstrated.     

聚合物栅绝缘层厚度对并五苯有机场效应管性能的影响

采用不同厚度的聚甲基丙烯酸甲酯(PMMA)作为栅绝缘层,制备了并五苯有机场效应晶体管(OFET)。测量了不同厚度的PMMA的介电特性,并详细分析了栅绝缘层厚度对器件性能的影响。其中,采用260nm厚的PMMA栅绝缘层的OFET具有比采用其它厚度的器件更优越的性能,其场效应迁移率、阈值电压与开关电流比分别达到3.39×10-3 cm2/Vs、-19V和103。