Transverse magnetoresistance peculiarities of thermoelectric Lu-doped Bi2Te3 compound due to strong electrical disorder

The n-type thermoelectric Bi_1.9Lu_0.1Te₃ was prepared by microwave-solvothermal method and spark plasma sintering. The magnetic field and temperature dependences of transverse magnetoresistance measured within temperature 2–200 K interval allow finding the peculiarities characteristic for strongly disordered and inhomogeneous semiconductors. The first peculiarity is due to appearance of linear-in-magnetic field contribution to the total magnetoresistance reflected in a crossover from quadratic magnetoresistance at low magnetic fields to linear magnetoresistance at high magnetic fields. The linear magnetoresistance can result from the Hall resistance picked up from macroscopically distorted current paths due to local variations in stoichiometry of the compound studied. The second peculiarity is that both linear magnetoresistance magnitude and crossover field are functions of carrier mobility which is in agreement with the Parish and Littlewood model developed for disordered and inhomogeneous semiconductors. An increase in the mobility due to a decrease in temperature is accompanied by an increase in the magnetoresistance magnitude and a decrease in the crossover field. Finally, the third peculiarity is related to the remarkable deviation of the total magnetoresistance measured at various temperatures from the Kohler's rule. Presence of strong inhomogeneity and disorder in the Bi_1.9Lu_0.1Te₃ structure concluded from the magnetoresistance peculiarities can be responsible for the remarkable reduction in the total thermal conductivity of this compound.     

Effect of carriers on deposition morphologies and catalytic performances of NiCo2O4

In this study, NiCo₂O₄ with different morphologies were fabricated using carriers by homogeneous coprecipitation combined with a sintering method. The phase and microstructure were characterized by XRD, SEM, EDS, TEM and BET, and the catalytic performances were investigated by NaBH₄ hydrolysis experiments. These studies revealed that the deposition morphology of NiCo₂O₄ can be adjusted by using different kinds of carrier templates, and the supported NiCo₂O₄ samples presented the pine-needle-like, network-like, ball-cactus-like and dandelion-like morphologies respectively. The optimal catalytic activity, durability and stability make the network-like NiCo₂O₄ an appropriate catalyst for hydrogen generation of NaBH₄ hydrolysis. It was found that the network-like NiCo₂O₄ is the most reusable and durable catalyst for ten consecutive cycles and 100% hydrogen generation conversion rate without obvious decrease among these morphologies.     

Oxygen vacancy levels on gadolinia-doped ceria interlayer deposited by atmospheric pressure plasma jet for solid oxide fuel cells

The oxygen vacancy levels as a factor on different gadolinia-doped ceria interlayer (GDCi) films deposited on yttria stabilized zirconia (YSZ) electrolyte substrates by an atmospheric pressure plasma jet (APPJ) via precursor solution of nitrate salts are investigated. Focusing on the effect of carrier gases, scanning electron microscopy (SEM), Raman, and X-ray diffraction (XRD) are implemented for the materials characterization of the as-deposited GDCi films and sintered-GDCi films at various temperatures. The higher level of oxygen vacancies in GDCi films adhered on 8YSZ electrolyte are evidently analyzed using Ar as the carrier gas during the deposition, of which the interdiffusion resulted in the formation of (GDC + YSZ) solid solution for sintering over 1300?°C degraded the total conductivity. The deposition of GDCi films on 8YSZ by APPJ method using O₂ carrier gas significantly improved the total conductivities of the whole electrolyte layers. Moreover, this study provides the useful insight into the oxygen vacancy levels on GDC films as interlayer (GDCi) to improve the values of open circuit voltage in LSM/GDCi/YSZ/Pt full-cell, as well as offering the efficiency of APPJ as one step deposition process.     

In-situ synthesis of ternary heterojunctions via g-C3N4 coupling with noble-metal-free NiS and CdS with efficient visible-light-induced photocatalytic H2 evolution and mechanism insight

The two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) nanosheets based composites are prepared in the form of the NiS/g-C₃N₄, CdS/g-C₃N₄ and CdS/NiS/g-C₃N₄ using a facile and reliable method of chemical deposition. The TEM and HRTEM images demonstrated a spectacular representation of the 2D lamellar microstructure of the g-C₃N₄ with adequately attached CdS and NiS nanoparticles. The changes in crystallinity and the surface elemental valence states of composites with the incorporation of two metal sulphides are studied, which confirmed the formation of composites. The photocatalytic response of the composites was estimated by photodegradation of Rhodamine B (C₂₈H₃₁ClN₂O₃–RhB), and the ternary composite CdS/NiS/g-C₃N₄ samples exhibited the superior photocatalytic performance. Further, the free radical capture and electron paramagnetic resonance (EPR) spectroscopy experiments identified the main active species that contributed to the photocatalytic reaction. Besides, the samples’ photocatalytic performance was evaluated by photocatalytic hydrogen production. The stability of the performance-optimized composite was determined by employing cyclic experiments over five cycles. The CdS/NiS/g-C₃N₄ showed the highest efficiency of hydrogen production i.e. about 423.37 μmol.g^?1.h^?1, which is 2.89 times that of the pristine g-C₃N₄. Finally, two types of heterojunction structures were proposed to interpret the enhanced photocatalytic efficiency.     

带式输送机托辊间距的合理确定

根据输送带垂直限制条件、避免输送带共振条件、托辊轴的刚度限制条件以及托辊轴承的寿命限制条件,给出了正常直线段托辊间距的确定方法,对托辊间距进行了分级。根据受力情况,给出了过渡段托辊间距、凸凹曲线段托辊间距和受料缓冲段托辊间距的确定方法,并附有应用实例。     

城市设计的载体──城市景观规划新探──以秀屿市区景观规划为例

城市设计应该融于城市规划的全过程，因此，城市总体规划阶段也应该进行相应的城市设计，即整体城市设计。城市景观规划是实现整体城市设计的主要手段，是整体城市设计内容的载体。文章结合莆田市秀屿市区景观规划实践，对城市总体规划阶段如何创造高质量的城市空间环境进行粗略的探索。     

论电力线通信技术在智能建筑中的应用

介绍电力线通信技术(简称PLC)及剖析其优缺点,并阐述了电力线通信技术在智能化建筑及数字化社区建设中的应用前景。     

双频载波相位平滑码伪距差分技术研究

本文针对载波相位平滑伪距差分技术在高精度测量的应用,推导了单频和双频载波相位平滑伪距的原理,分别给出了单频和双频载波相位平滑伪距差分模型。通过试验分析,比较了单频和双频差分导航定位精度,分析了双频载波相位平滑伪距差分定位的优点,且其差分定位精度可达亚米级。     

基于立面特征的建筑照明方式研究

夜幕下的建筑立面在灯光的渲染 下呈现出不同于白天的魅力和情感，合理的 建筑照明不仅能够突出建筑自身的个性特 色，还提升了文化内涵与情感表达。然而， 目前多数建筑物的照明设计不合理，导致了 建筑原有特色与内涵的缺失。因此，需要 针对建筑物的立面照明进行相关研究，以 实现对建筑固有特色的回应。文章从城市 中现存建筑物风格类型出发并梳理不同风 格建筑的立面特征，研究照明方式不同表 现特征达到的照明效果，总结不同立面特 征最适宜的照明方式。     

2020年电子电路技术热点

文章归纳了2020年电子电路产业一些技术热点,主要有5G电路板设计和基材,制造方面半加成法、3D打印、直接金属化孔电镀和垂直互连结构等技术,以及集成电路封装载板技术。