半导体纳米粒子改性变压器油的绝缘性能及机制研究

磁性导电纳米粒子可以提高变压器油的导热和绝缘特性,但其分散性极易受到磁场的影响,不利于变压器油性能的改善。利用半导体纳米粒子对变压器油进行改性,测量了改性前后变压器油的工频击穿特性、雷电击穿特性和局部放电特性,可知半导体纳米粒子不仅可以使变压器油的工频和雷电击穿电压提高至未改性变压器油的1.2倍,而且可以改善变压器油的局部放电特性。由于现有的电子捕捉理论无法解释这种现象,利用热刺激电流(thermally stimulated current,TSC)法对改性前后变压器油中的陷阱特性进行了测试,结果表明:纳米粒子的加入增加了变压器油中的浅陷阱密度,提高了变压器油对电荷的消散和输运能力,从而能够改善变压器油的绝缘性能。     

Prevention of marginal corona discharges in the insulation of high-voltage electric machines

The problem of preventing corona glowing discharges at the junction of slot and end-winding semiconductive coatings is investigated. Allowable electrical stress and current density are determined and used to calculate the two-step stress-grading coating. The proposed construction of end-winding coatings was used to produce 20-kV turbogenerators and checked by long-term sample testing.     

Bio‐Erasable Intermolecular Donor–Acceptor Interaction of Organic Semiconducting Nanoprobes for Activatable NIR‐II Fluorescence Imaging

Activatable second near‐infrared window (NIR‐II; 1.0–1.7 µm) fluorescence probes that uncage deep‐tissue penetrating fluorescence by disease‐related biomarker stimuli hold great promise for detecting diseases with a poor understanding of the pathology at the molecular level with unprecedented resolution. However, currently, very few activatable NIR‐II fluorescence probes are reported mainly due to the lack of a simple yet general design strategy. Herein, a new and fairly generic design strategy using a bio‐erasable intermolecular donor–acceptor interaction to construct activatable NIR‐II fluorescence probes is reported. An organic semiconducting nanoprobe (SPNP) is constructed through blending a biomarker‐sensitive organic semiconducting non‐fullerene acceptor (3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐cyclopentane‐1,3‐dione‐[c]thiophen))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2',3'‐d']‐s‐indaceno[1,2‐b:5,6‐b'] dithiophene) (ITTC) (one of electric acceptors in organic solar cells) with a biomarker‐inert semiconducting polymer donor 5‐(4,8‐bis((2‐ethylhexyl)oxy)‐6‐methylbenzo[1,2‐b:4,5‐b']difuran‐2‐yl)‐10‐methylnaphtho[1,2‐c:5,6‐c']bis([1,2,5]thiadiazole) (PDF) in an amphiphilic‐polymer‐coated single nanoparticle to suppress NIR‐II fluorescence of the donor via a intermolecular donor–acceptor interaction. The acceptor ITTC is found to be specifically degraded by hypochlorite (an important biomarker) to erase its acceptor property, thus erasing the intermolecular donor–acceptor interaction and uncaging NIR‐II fluorescence. Consequently, SPNP exhibits a 17.5‐fold higher fluorescence brightness in the hypochlorite‐abnormal inflammation in vivo than in normal tissues. Our bio‐erasable intermolecular donor–acceptor interaction strategy provides simple yet general guidelines to design various biomarker‐activatable NIR‐II fluorescence probes.     

掺Y~（3＋）、La~（3＋）的（Sr，Ca）TiO_3系多功能陶瓷

用稀土离子Ｙ（３＋）、Ｌａ（３＋）对（Ｓｒ，Ｃａ）ＴｉＯ３掺杂，以Ｂａ－Ｓｉ－Ａｌ玻璃为助熔剂，在１３５０～１４５０℃还原性气氛中烧成，获得工艺性能良好、烧结温度较低、晶粒电阻率低（１０（－２）Ω·ｃｍ）、非线性高（α达１０以上）的陶瓷材料。在制备过程中省略了以往用碱金属离子涂覆并进行热扩散的工序。用缺陷化学理论，根据测量的ＩＣＴＳ谱、Ｉ－Ｖ特性和Ｃ－Ｖ特性系统研究了Ｙ（３＋）、Ｌａ（３＋）掺杂对晶粒半导化、压敏特性和介电特性的影响。热处理过程中，Ｏ－的化学吸附是这类陶瓷产生晶界势垒的主要原因。     

BaTiO_3半导瓷材料中施受主杂质互补作用的研究

对施主掺杂而言，在缺位补偿区，引入高受主掺杂可使材料的常温电阻率随受主杂质的引入量增加呈Ｕ型曲线变化，同时晶粒尺寸随之单调上升。这是由于受主杂质的引入利于产生氧空位，导致钡空位浓度下降的结果。     

Imparting Metal Oxides with High Sensitivity Toward Light-Activated NO2 Detection Via Tailored Interfacial Chemistry

Activation of metal oxides by light is a robust yet facile approach to manipulating their surface chemistry for favorable reactions with target molecules in heterogeneous catalysis and gas sensors. However, a limited understanding of interface chemistry and the involved mechanism impedes the development of a rational design of oxide interfaces for light-activated gas sensing. Herein, the TiO_x-assisted photosensitization of In₂O₃ toward NO₂ sensing is investigated as a case study to elucidate the detailed mechanism of light-activated surface chemistry at the metal/gas interface. The resultant heterogeneous oxides exhibit outstanding NO₂ sensing performance under light irradiation thanks to abundant photoexcited electrons and holes that serve as adsorption and desorption sites, respectively, to accelerate both surface reactions. Furthermore, the facile transfer of electrons and holes across the TiO_x-In₂O₃ interface contributes to improving the reversibility of sensing kinetics. Through this study, the mechanistic understanding is established of how the surface chemistry of metal oxide surfaces can be tuned by light activation providing an effective route to the design fabrication of high-performance gas sensors.     

Multifunctional Visible‐Light Powered Micromotors Based on Semiconducting Sulfur‐ and Nitrogen‐Containing Donor–Acceptor Polymer

Photosensitive micromotors that can be remotely controlled by visible light irradiation demonstrate great potential in biomedical and environmental applications. To date, a vast number of light‐driven micromotors are mainly composed from costly heavy and precious metal‐containing multicomponent systems, that limit the modularity of chemical and physical properties of these materials. Herein, a highly efficient photocatalytic micromotors based exclusively on a purely organic polymer framework—semiconducting sulfur‐ and nitrogen‐containing donor–acceptor polymer, is presented. Thanks to precisely tuned molecular architecture, this material has the ability to absorb visible light due to a conveniently situated energy gap. In addition, the donor‐acceptor dyads within the polymer backbone ensure efficient photoexcited charge separation. Hence, these polymer‐based micromotors can move in aqueous solutions under visible light illumination via a self‐diffusiophoresis mechanism. Moreover, these micromachines can degrade toxic organic pollutants and respond to an increase in acidity of aqueous environments by instantaneous colour change. The combination of autonomous motility and intrinsic fluorescence enables these organic micromotors to be used as colorimetric and optical sensors for monitoring of the environmental aqueous acidity. The current findings open new pathways toward the design of organic polymer‐based micromotors with tuneable band gap architecture for fabrication of self‐propelled microsensors for environmental control and remediation applications.     

Na1.88Bi1.88S4和Na1.36Ca1.28Bi1.36S4单晶制备与结构及其光学性能表征

采用碘化钠为助熔剂,通过固相反应法制备了两种晶体质量较好的Na_1.88Bi_1.88S₄和Na_1.36Ca_1.28Bi_1.36S₄单晶。测试结果表明,它们属于氯化钠结构,面心立方,空间群为Fm-3m。形貌表征和物性测试结果表明,在碘化钠的作用下,化合物Na_1.88Bi_1.88S₄和Na_1.36Ca_1.28Bi_1.36S₄呈现双锥状形貌,沿(111)晶面择优取向生长,带隙分别为1.29和1.45 eV。通过光电器件性能测试,发现两种化合物均表现出良好的光电响应特性,说明它们可以作为一类潜在的、性能优良的光电开关材料。     

半导体玻璃微通道板制造工艺研究

体电导半导体玻璃微通道板具有优异的性能,为了突破其制造工艺的技术难关,研究和分析了过程技术参数以及缺陷成因.以磷酸盐系统半导体玻璃和酸溶玻璃作为微通道板单纤维的皮料和芯料,在电炉中熔制得到玻璃纤芯及皮料的母棒,然后根据两种玻璃的性能及工艺参数,采用光纤自动成纤系统研究了适合双坩埚法单丝拉制的工艺.重点讨论了拉丝温度和速度、玻璃液位、气氛等关键因素对成纤过程和微通道板质量的影响.通过单丝和复丝的拉制,排丝、压屏、切割和酸溶等过程,最终获得了直径为20 mm,孔径为6~7μm,像素大于400万的体电导玻璃微通道板的雏形.