BCB的制备及其对BNBW陶瓷微波性能的影响

在不同条件下采用固相反应法合成BaCu(B2O5)(BCB)粉体,研究了所合成的BCB粉体对Ba5Nb4O15-BaWO4(BNBW)陶瓷的微波介电性能的影响。结果表明,采用无水乙醇作为球磨介质,在800℃煅烧可以得到无杂相的BCB。将BCB作为助烧剂,添加少量于BNBW陶瓷中,在950℃烧结时可有效促进陶瓷致密化。随着BCB的掺量增加,BNBW陶瓷的介电常数εr和谐振频率温度系数τf单调降低,而品质因数与频率之积Q×f值先上升后下降。当w(BCB)=1%时,BNBW陶瓷得到较好微波性能:εr=19.0,Q×f=33 802GHz,τf=2.5×10-6/℃。     

a-Fe_2O_3纳米棒的制备研究

采用压力–热晶法,制得棒状的前躯体后再在600℃焙烧8 h,成功地制得直径在20~40 nm,长度在300~500 nm之间,均匀分散、疏松多孔的六方结构的棒状Fe2O3纳米粒子,并用透射电子显微镜、电子衍射、X射线衍射等技术手段对样品进行了表征,考察了制备条件对产物粒径、形貌的影响。结果表明:初始铁盐浓度对产物粒径影响不明显,可以在较高初始浓度下制备Fe2O3纳米粒子;pH值、初始压力对粒子形貌和大小有一定的影响。     

火电厂输煤程控系统的研究与设计

本文在分析电厂输煤程控系统的工艺流程、控制需求的基础上,给出以西门子PLC-300、Win CC的上位机监控系统及ET-200的远程I/O设备为结构的DCS系统,文中介绍了该集散控制系统的特点、系统配置及所实现的功能。该控制系统具有多重控制方式,实现了对整个生产系统的实时在线监控。     

基于PC总线的位置测量与电机控制卡

由于光栅,步进电机以及ＩＰＣ工业控制机在机械工业尤其是数控领域中普遍采用,研制出集光栅益检测与步进电机控制两个功能一体的适用于ＩＰＣ工控机的接口卡具有实用价值。文章介绍了基于ＰＣ总线的接口卡的设计,包括硬件结构体系,组成接口卡的几个功能模块以及误差测量控制系统的软件设计,并给出了应用实例。采用该体系结构,在丝杠磨床上实现了传动误差的测量与补偿,大大减小了丝杠传动误差。     

含La或Sm的BaNd_(2-y)R_yTi_(4+x)O_(12+2x)瓷的结构与性能

ＢａＯ－Ｎｄ２Ｏ３－ＴｉＯ２系富钛区含Ｌａ或Ｓｍ的陶瓷,ＸＲＤ、ＳＥＭ显微结构分析表明,其主晶相为Ｒ（Ｒ＝Ｌａ或Ｓｍ）取代Ｎｄ固溶体ＢａＮｄ２－ｙＲｙＴｉ５Ｏ１４和ＢａＮｄ２－ｙＲｙＴｉ４Ｏ１２,均属斜方晶系,并存在少量的次晶相Ｒ２Ｔｉ２Ｏ７、ＢａＴｉ４Ｏ９、Ｂａ２Ｔｉ９Ｏ２０等。富钛区ＢａＮｄ２Ｔｉ４＋ｘＯ１２＋２ｘ（ｘ＝０～１．４００）组分和含Ｌａ或Ｓｍ的ＢａＮｄ２－ｙＲｙＴｉ５Ｏ１４组分所组成的瓷料,介质损耗显著地降低,介电常数和电容温度系数遵从李赫涅德凯对数混合定律。     

肿瘤热疗用Fe3O4磁性纳米粒的制备及表征

用化学共沉淀法制备用于肿瘤磁流体热疗的Fe3O4磁性纳米粒子并对其进行表征。运用透射电子显微镜、X射线衍射分析、扫描电子显微镜、能谱分析及图像分析等技术进行特性研究;在高频交变磁场下观察Fe3O4纳米磁流体的体外升温情况。制备的Fe3O4磁性纳米粒子属尖晶石型铁氧体、圆形,粒径20nm左右。其不同浓度的磁流体在高频交变磁场下可升温至37℃～56℃。     

Surface State Mediated NIR Two‐Photon Fluorescence of Iron Oxides for Nonlinear Optical Microscopy

The development of fluorescent iron oxide nanomaterials is highly desired for multimodal molecular imaging. Instead of incorporating fluorescent dyes on the surface of iron oxides, a ligand‐assisted synthesis approach is developed to allow near‐infrared (NIR) fluorescence in Fe₃O₄ nanostructures. Using a trimesic acid (TMA)/citrate‐mediated synthesis, fabricated Fe₃O₄ nanostructures can generate a NIR two‐photon florescence (TPF) peak around 700 nm under the excitation by a 1230‐nm femtosecond laser. By tailoring the absorption of Fe₃O₄ nanostructures toward NIR band, the NIR‐TPF efficiency can be greatly increased. Through internal etching, surface peeling, and ligand replacement, spectroscopic results validated that such resonantly enhanced NIR‐TPF is mediated by surface states with strong NIR‐IR absorption. This TPF signal evolution can be generalized to other iron oxide nanomaterials like magnetite nanoparticles and α‐Fe₂O₃ nanoplates. Using the developed fluorescent Fe₃O₄ nanostructures, it is demonstrated that their TPF and third harmonic generation (THG) contrast in the nonlinear optical microscopy of live cells. It is anticipated that the synthesized NIR photofunctional Fe₃O₄ will serve as a versatile platform for dual‐modality magnetic resonance imaging (MRI) as well as a magnet‐guided theranostic agent.     

Comprehensively Strengthened Metal-Oxygen Bonds for Reversible Anionic Redox Reaction

Introducing anionic redox in layered oxides is an effective approach to breaking the capacity limit of conventional cationic redox. However, the anionic redox reaction generally suffers from excessive oxidation of lattice oxygen to O₂ and O₂ release, resulting in local structural deterioration and rapid capacity/voltage decay. Here, a Na_0.71Li_0.22Al_0.05Mn_0.73O₂ (NLAM) cathode material is developed by introducing Al³⁺ into the transition metal (TM) sites. Thanks to the strong Al–O bonding strength and small Al³⁺ radius, the TMO₂ skeleton and the holistic TM–O bonds in NLAM are comprehensively strengthened, which inhibits the excessive lattice oxygen oxidation. The obtained NLAM exhibits a high reversible capacity of 194.4 mAh g^-1 at 20 mA g^-1 and decent cyclability with 98.6% capacity retention over 200 cycles at 200 mA g⁻¹. In situ characterizations reveal that the NLAM experiences phase transitions with an intermediate OP4 phase during the charge–discharge. Theoretical calculations further confirm that the Al substitution strategy is beneficial for improving the overlap between Mn 3d and O 2p orbitals. This finding sheds light on the design of layered oxide cathodes with highly reversible anionic redox for sodium storage.     

High emission performance impregnated dispenser cathode

In order to obtain higher emission performance than that of a traditional M-type cathode, we have developed a new type impregnated dispenser cathode. The new cathode is impregnated with a new active substance with molar ratio of 26BaO·29SrO·8Sc2O3 ·7CaO·Al2O3 . This paper introduces the emission performance, surface active material, and work function of the new cathode. At 1100℃B , the DC current density and pulse current density are 30.6±1.0 A/cm2 and 171.6±2.8 A/cm2 , respectively, 2.1 and 5.4 times of that of an M-type cathode. The work function of the new cathode is 1.668± 0.002 eV. High concentration O-Al-Sc-Sr-Ba and O-Al-Sc-Ba are found in the pores and at pore edges, respectively. By comparing the emission performances and surface characteristics of as-polished and as-cleaned cathodes, it is proposed that, the emission around pore ends forms the major part of the total emission for the new cathodes.     

Unraveling the Significance of Li+/e−/O2 Phase Boundaries with a 3D-Patterned Cu Electrode for Li–O2 Batteries

The reaction kinetics at a triple-phase boundary (TPB) involving Li⁺, e⁻, and O₂ dominate their electrochemical performances in Li–O₂ batteries. Early studies on catalytic activities at Li⁺/e⁻/O₂ interfaces have enabled great progress in energy efficiency; however, localized TPBs within the cathode hamper innovations in battery performance toward commercialization. Here, the effects of homogenized TPBs on the reaction kinetics in air cathodes with structurally designed pore networks in terms of pore size, interconnectivity, and orderliness are explored. The diffusion fluxes of reactants are visualized by modeling, and the simulated map reveals evenly distributed reaction areas within the periodic open structure. The 3D air cathode provides highly active, homogeneous TPBs over a real electrode scale, thus simultaneously achieving large discharge capacity, unprecedented energy efficiency, and long cyclability via mechanical/electrochemical stress relaxation. Homogeneous TPBs by cathode structural engineering provide a new strategy for improving the reaction kinetics beyond controlling the intrinsic properties of the materials.