Electrochemical performance of a nonaqueous rechargeable lithium-air battery

Nonaqueous rechargeable lithium-air battery has so high specific capacity and specific energy that it is being widely researched by academia, corporation, and different research institutes. When used in dried air and absorbing oxygen form the air, this battery is called lithium-air battery, and its specific capacity based on cathode active material (oxygen) is infinite. However, its cycle performance is very limited as reported by the state-of-the-art researches. This cycle problem is mainly caused by instability of electrolyte. Based on electroanalysis of materials’ electrochemical property, a stable electrolyte solvent (sulfolane) and a lithium salt LiBF₄ are selected as electrolytes in this work. Coupled with other eligible battery materials and careful assembly, the lithium-air battery exhibits favorable cycle performance. Above all, this lithium-air system is evaluated objectively in this paper.     

Hollow glass microspheres coated with CoFe2O4 and its microwave absorption property

Spinel CoFe₂O₄ coating on the surface of hollow glass microspheres of low density was synthesized by co-precipitation method. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDS). The results show that CoFe₂O₄ coating on hollow glass microspheres can be achieved, and the coating layers are constituted by CoFe₂O₄ nanoparticles of mean size ca. 10 nm. The as-synthesized powder materials were uniformly dispersed into the phenolic cement, then the mixture was pasted on metal plate with the area of 200 mm×200 mm as the test plate. The test of microwave absorption was carried out by the radar-absorbing materials (RAM) reflectivity far field radar cross-section (RCS) method. The results indicate that the coated CoFe₂O₄/hollow glass microspheres composites can be applied in lightweight and strong absorption microwave absorbers.     

Mesoporous material grafted with luminescent molecules for the design of selective metal ion chemosensor

Luminescent Schiff-base groups have been successfully grafted on the surface of mesoporous material MCM-48. The grafted Schiff-base groups were employed to prepare luminescent Schiff-base-Zn complex that was covalently bound to the MCM-48 surface. These luminescent mesoporous materials were characterized with X-ray, UV-VIS and emission spectroscopic methods. Experimental results demonstrated that MCM-48 modified with functional groups exhibited novel luminescent property. The chemosensing property of modified MCM-48 sample was investigated. It was demonstrated that the fluorescence of MCM-48 solid with Schiff-base groups could be completely quenched by Cu²⁺ cation and this mesoporous material was suitable for sensing Cu²⁺ cation in aqueous media.     

Highly stable amorphous indium‐zinc‐oxide thin‐film transistors with back‐channel wet‐etch process

The stabilities of amorphous indium‐zinc‐oxide (IZO) thin film transistors (TFTs) with back‐channel‐etch (BCE) structure are investigated. A molybdenum (Mo) source/drain electrode was deposited on an IZO layer and patterned by hydrogen peroxide (H₂O₂)‐based etchants. Then, after etching the Mo layer, SF₆ plasma with direct plasma mode was employed and optimized to improve the bias stress stability. Scanning electron microscopy and X‐ray photoelectron spectroscopic analysis revealed that the etching residues were removed efficiently by the plasma treatment. The modified BCE‐ TFTs showed only threshold voltage shifts of 0.25 V and –0.20 V under positive/negative bias thermal stress (P/NBTS, V_GS = ±30 V, V_DS = 0 V and T = 60 °C) after 12 hours, respectively. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Introduction and Applications of a Generalized Intermediate Entangled State Representation

We introduce a generalized intermediate entangled state representation ｜β〉Λ to study the energy spectrum of an electron in a uniform magnetic field and a harmonic potential through algebraic calculatiOn. We find that the degeneracy of the energy levels is disappeared due to the existence of the additional potential. We make it clear that the eigenfunction is just the expression of eigenvector, defined in n Fock space, in ｜β〉Λ representation.     

Determination of the in-plane anisotropy field in hexagonal systems via rotational magnetization: Theoretical model and Monte Carlo simulations

The magnetic anisotropy field in thin films with in-plane uniaxial anisotropy can be deduced from the VSM magnetization curves measured in magnetic fields of constant magnitudes. This offers a new possibility of applying rotational magnetization curves to determine the first- and second-order anisotropy constant in these films. In this paper we report a theoretical derivation of rotational magnetization curve in hexagonal crystal system with easy-plane anisotropy based on the principle of the minimum total energy. This model is applied to calculate and analyze the rotational magnetization process for magnetic spherical particles with hexagonal easy-plane anisotropy when rotating the external magnetic field in the basal plane. The theoretical calculations are consistent with Monte Carlo simulation results. It is found that to well reproduce experimental curves, the effect of coercive force on the magnetization reversal process should be fully considered when the intensity of the external field is much weaker than that of the anisotropy field. Our research proves that the rotational magnetization curve from VSM measurement provides an effective access to analyze the in-plane anisotropy constant K ₃ in hexagonal compounds, and the suitable experimental condition to measure K ₃ is met when the ratio of the magnitude of the external field to that of the anisotropy field is around 0.2. Supported by the National Natural Science Foundation of China (Grant Nos. 90505007 and 10774061) Recommended by LI FaShen     

光纤热极化过程的实时测试研究

通过热极化可以使中心对称的熔石英光纤中产生二阶非线性效应和线性电光效应。为了解各热极化过程参量对热极化产生的线性电光效应的影响,利用全保偏光纤马赫一曾德尔干涉仪构造了一套光纤热极化的实时线性电光效应测试系统,并利用其进行了光纤热极化全过程的监控测试。在线测试了热极化过程的一些参量,例如极化电压、极化时间、以及极化温度等对热极化光纤中产生的线性电光效应的影响。实时测试研究表明,在光纤中施加尽可能高的极化电场将可能在光纤中产生较高的线性电光效应。对侧边抛磨光纤结构的热极化器件,考虑到器件的抗强电场击穿能力,可选用3．o～4．0kV左右的极化直流电压。当施加3．0kV左右的极化电压时,热极化优化时间约为16min,最佳热极化加热温度约为190℃。     

PbS quantum dot fiber amplifier based on a tapered SMF fiber

A PbS quantum dot coated (QD-coated) tapered fiber amplifier with a broad bandwidth is theoretically demonstrated. The QD layer is coated on the surface of a tapered fiber and is excited by the evanescent wave of a pump. An optical gain of 10.5 dB, with a 160-nm broad bandwidth of at 1530-nm center wavelength, is achieved. The gain efficiency is over 4 dB/cm. This QD-tapered fiber amplifier has a concentration control of the QDs, a lower insertion loss, and shows good suppression of amplified spontaneous emission (ASE), while its structure is also quite simple. Therefore, the proposed fiber amplifier has great potential in fiber-optic communication systems.