工作气压对磁控溅射ITO薄膜性能的影响

工作气压在ITO薄膜的制备过程中是一个重要的工艺参数,直接决定着薄膜的性能.本文利用射频磁控溅射方法,采用氧化铟锡陶瓷靶材,在衬底温度为175℃,工作气压范围为0.45～1.0 Pa条件下,制备了氧化铟锡透明导电薄膜.研究了工作气压对其微观结构、表面形貌和光电特性的影响.在衬底温度为175℃、纯氩气中制备的氧化铟锡薄膜电阻率为3.04 ×10-4 Ω·cm、可见光波段(400～800 nm)透过率为91.9;,适合用作异质结太阳电池的前电极和减反射膜.     

6H-SiC衬底片的表面处理

相比于蓝宝石,6H-SiC是制作GaN高功率器件更有前途的衬底.本文研究了表面处理如研磨、化学机械抛光对6H-SiC衬底表面特性的影响.用显微镜、原子力显微镜、拉曼光谱、卢瑟福背散射谱表征了衬底表面.结果表明经过两步化学机械抛光后提高了表面质量.经第二步化学机械抛光后的衬底具有优异的表面形貌、高透射率和极小的损伤层,其表面粗糙度RMS是0.12nm.在该衬底上用MOCVD方法长出了高质量的GaN外延膜.     

Fe3+对KDP晶体光学质量的影响

金属离子Fe3+对KDP晶体的生长和光学性质有明显影响.本文在前期研究的基础上[1]系统考察了该杂质离子对KDP晶体光学质量的影响.实验结果表明,三价金属离子Fe3+会降低KDP晶体的透光率,同时对晶体均匀性和光损伤阈值也有明显影响.光损伤阈值降低的主要原因在于杂质诱发缺陷导致的电子崩电离、多光子电离(尤其是双光子电离)等过程的发生.     

Er3+:NaY(Wo.9Moo.1O4)2晶体的生长及光谱性能

采用提拉法(CZ法),生长出质量良好的Er3+:NaY(W0.9Mo0.1O4)2晶体.通过X射线粉末衍射,红外光谱分析,并与NaY(WO4)2相比较,得到Er3+:NaY(W0.9Mo0.1O4)2晶体的结构与NYW类似,仍为四方晶系的白钨矿结构,I4(1)/α空间群.测定了晶体的实际组成,得到晶体中各元素均按理论值进行掺杂,计算了掺杂离子的分凝系数约为1.15.在光谱性质上,测试了晶体的吸收光谱,及晶体在50～1000cm-1波数范围内的拉曼光谱,并计算了各吸收峰的半峰宽及吸收系数A.     

High-performance potassium poly(heptazine imide) films for photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is an appealing approach by which to convert solar energy into hydrogen fuel. Polymeric semiconductors have recently attracted intense interest of many scientists for PEC water splitting. The crystallinity of polymer films is regarded as the main factor that determines the conversion efficiency. Herein, potassium poly(heptazine) imide (K-PHI) films with improved crystallinity were in situ prepared on a conductive substrate as a photoanode for solar-driven water splitting. A remarkable photocurrent density of ca. 0.80 mA cm⁻² was achieved under air mass 1.5 global illumination without the use of any sacrificial agent, a performance that is ca. 20 times higher than that of the photoanode in an amorphous state, and higher than those of other related polymeric photoanodes. The boosted performance can be attributed to improved charge transfer, which has been investigated using steady state and operando approaches. This work elucidates the pivotal importance of the crystallinity of conjugated polymer semiconductors for PEC water splitting and other advanced photocatalytic applications.

Potassium poly(heptazine imide) photoanode is synthesized, and owing to the improved crystallinity, it has presented a remarkable performance for solar-driven water splitting.     

Alkene insertion reactivity of a o-carboranyl-substituted 9-borafluorene

The synthesis of 9-borafluorene with an electron-withdrawing o-carboranyl substituent and its reactions with a series of alkenes are described. The o-carboranyl substituent is bonded via one of the cluster carbon atoms to the boron atom of the 9-borafluorene moiety. In all cases, the reactions afford partly saturated analogs of borepins (i.e. 6,7-dihydroborepins) by unprecedented alkene insertion into the endocyclic B–C bond of the borole ring. Comparative studies with 9-bromo-9-borafluorene illustrate the superior insertion reactivity of the carboranyl-substituted derivative. A suite of experimental and computational techniques disclose the unique properties of the 9-borafluorene and provide insight into how the 9-carboranyl substituent affects its chemical reactivity.

A 9-carboranyl-substituted 9-borafluorene is reported, which is capable of undergoing efficient ring expansion to 6,7-dihydroborepins by a previously unknown alkene insertion.     

Preface

This special issue of the journal Numerical Mathe-matics: Theory, Methods and Applications is dedicated to Professor Yucheng Su of Nanjing University (China) on the occasion of his eightieth birthday. It consists of eight papers covering computational methods of partial differential equations, where most of the equations are singularly perturbed.     

Conserved Control Path in Multilayer Networks

The determination of directed control paths in complex networks is important because control paths indicate the structure of the propagation of control signals through edges. A challenging problem is to identify them in complex networked systems characterized by different types of interactions that form multilayer networks. In this study, we describe a graph pattern called the conserved control path, which allows us to model a common control structure among different types of relations. We present a practical conserved control path detection method (CoPath), which is based on a maximum-weighted matching, to determine the paths that play the most consistent roles in controlling signal transmission in multilayer networks. As a pragmatic application, we demonstrate that the control paths detected in a multilayered pan-cancer network are statistically more consistent. Additionally, they lead to the effective identification of drug targets, thereby demonstrating their power in predicting key pathways that influence multiple cancers.     

PVC/MBS/纳米 BaSO4 复合材料的制备及其性能

采用熔融共混法制备聚氯乙烯(PVC)/甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物(MBS)/纳米重晶石(nano-BaSO4)三元复合材料,考察其力学性能和热稳定性能,并用扫描电镜观察冲击断面的形态.结果表明:MBS 与 nano-BaSO4 可协同增韧 PVC;当 MBS、nano-BaSO4 的含量分别为 10%、1%时,材料的韧性和刚性可同时得以改善,其冲击断面表现出典型的韧性断裂特征;热重分析显示添加 1%nano-BaSO4 可显著提高 PVC/MBS 的热稳定性能,其第一降解阶段的初始分解温度和最快分解温度分别提高了 10℃和14℃.