Enabling electrically tunable radio frequency components with advanced microfabrication and thin film techniques

Multi-function,multiband,cost-effective,miniaturized reconfigurable radio frequency(RF)components are highly demanded in modern and future wireless communication systems.This paper discusses the needs and implementation of multiband reconfigurable RF components with microfabrication techniques and advanced materials.RF applications of fabrication methods such as surface and bulk micromachining techniques are reviewed,especially on the development of RF microelectromechanical systems(MEMS)and other tunable components.Works on the application of ferroelectric and ferromagnetic materials are investigated,which enables RF components with continuous tunability,reduced size,and enhanced performance.Methods and strategies with nano-patterning to improve high frequency characteristics of ferromagnetic thin film(e.g.,ferromagnetic resonance frequency and losses)and their applications on the development of fully electrically tunable RF components are fully demonstrated.

固体氧化物燃料电池(SOFC)低温化研究进展

固体氧化物燃料电池(SOFC)的低温化已成为SOFC商业化发展的必然趋势。目前,SOFC低温化的主要策略是通过制备电解质薄膜以降低电解质的厚度和研发新型电解质材料以提高电解质的离子电导率。本文简述了SOFC的工作原理,从电解质薄膜的制备技术及新型电解质材料的应用两个方面对SOFC低温化的研究进展进行了论述,探讨了干压法、流延法、沉积法及等离子喷涂法等技术的优劣之处,对比分析了锆基电解质材料、铈基电解质材料、铋基电解质材料及质子导体基电解质材料在中低温区间(400~700℃)的离子电导率,并指出了在SOFC商业化进程中亟待解决的问题。

固体氧化物燃料电池(SOFC)合金连接体耐高温氧化导电防护涂层

降低固体氧化物燃料电池(SOFC)工作温度,可使用高电导、高热导、高强度的合金作为连接体。其中含Cr的铁素体不锈钢合金,具有与SOFC其他部件材料匹配的热膨胀系数,此外还有易于加工及成本低廉等优点,成为中低温板式SOFC连接体材料应用与研究的重点。但这类合金表面高温氧化所带来的界面电阻变化,及Cr挥发进而在阴极沉积所带来的诸多问题,成为影响板式SOFC长期稳定的关键因素,因此必须进行有效的表面处理。从SOFC合金连接体引起的电堆性能衰减机理出发,阐明了降低或防止阴极Cr中毒的几类方法,论述了合金连接体涂层的必要性。结合笔者开发设计的尖晶石粉末还原法在合金连接体表面制备纳米微结构Mn_(0.9)Y_(0.1)Co_2O_4(MYC)防护涂层方面的工作,综述了国内外SOFC合金连接体涂层材料及涂层制备方法的研究进展。对各类涂层材料及涂层制备方法优缺点进行比较的同时,重点介绍了电导率高、实用性较强的钙钛矿结构及尖晶石结构涂层材料。最后展望了合金连接体涂层的发展前景。

电泳沉积在制备SOFC电解质膜中的应用

利用电泳沉积技术制备固体氧化物燃料电池(SOFC)电解质膜具有一些突出的优点,在此领域的研究近年来取得了很大的进展。综合介绍了电泳沉积技术在制备SOFC电解质膜中的应用研究情况,其中包括电泳沉积的基本原理、胶体悬浮液的配置、沉积基体的选择以及沉积工艺参数的影响。重点评述了悬浮液配置方面的问题,分析了电解质颗粒、溶剂以及各种添加剂的选择和处理方法。

阳极对YSZ薄膜SOFC性能的影响

研究了两种阳极对YSZ薄膜固体氧化物燃料电池(SOFC)性能的影响。NiO-YSZ阳极和NiO-SDC-YSZ阳极支撑的YSZ薄膜电池,在800℃时的开路电压分别为1.09 V和0.87 V,最大功率密度分别为0.86 W/cm2和0.16 W/cm2。NiO-SDC-YSZ阳极电池的电极总阻抗比NiO-YSZ阳极电池的高出58%。

Application of Filming Technique in the DUS Test for PVP Information

As the great progress has appeared in the field of protection of new varieties of plants, the standardization of the DUS （Distinctness, Uniformity, Stability） test procedure has become more important. However, the specification of filming technique plays an important role in the DUS test of new varieties of plants. In this paper, we analyzed the status quo and significance of the application of filming technique in the PVP （Plant Variety Protection） system, and provided an introduction about the application of filming technique in DUS test in China.

Light Simplified Cultivation Techniques of Wide Row and Double Ridge with Filming, Fertilizing and Sowing on One for Foxtail Millet

In view of the problems of completely depending on rain, low and unstable yield and complicated planting of dry land foxtail millet, the light simplified cultivation techniques of wide row and double ridge with filming, fertilizing and sowing on one for foxtail millet was formed through the integration of plastic film mulching technology and mechanized production technology by Institute of Millet crops of Hebei Academy of Agriculture and Forestry Sciences, and the techniques were introduced from the key technologies of pre-sowing preparation, sowing, supporting equipment, field management, harvesting, plastic film recycling.

An overview of thermoelectric films:Fabrication techniques,classification,and regulation methods

Thermoelectric materials have aroused widespread concern due to their unique ability to directly convert heat to electricity without any moving parts or noxious emissions.Taking advantages of two-dimensional structures of thermoelectric films,the potential applications of thermoelectric materials are diversified,particularly in microdevices.Well-controlled nanostructures in thermoelectric films are effective to optimize the electrical and thermal transport,which can significantly improve the performance of thermoelectric materials.In this paper,various physical and chemical approaches to fabricate thermoelectric films,including inorganic,organic,and inorganic–organic composites,are summarized,where more attentions are paid on the inorganic thermoelectric films for their excellent thermoelectric responses.Additionally,strategies for enhancing the performance of thermoelectric films are also discussed.

Synthesis and Electrical Characterization of BaTiO3 Thin Films on Si(100)

BaTiO3 thin film has been deposited on Si(100) substrate using sol-gel process and deposited by using spin – coating technique. The BaTiO3/Si(100) structures were studied by structural and electrical characteristics. The X-ray diffrac-tion of BaTiO3/Si(100) shows that the diffraction peaks become increasing sharp with increasing calcination tempera-tures indicating the enhance crystallinity of the films. Scanning electron microscopy of BaTiO3 thin films shows the crack free and uniform nature. The capacitance-voltage measurement of BaTiO3 thin film deposited on Si(100) an-nealed at 600℃ shows large frequency dispersion in the accumulation region. The current-voltage measurement of BaTiO3/Si shows the ideality factor was approaches to unity at 600℃.

Synthesis Sol-Gel Derived Highly Transparent ZnO Thin Films for Optoelectronic Applications

In this work, ZnO thin films were derived by sol-gel using two different techniques;dip coating and spin coating technique. The films were deposited onto glass substrate at room temperature using sol-gel composed from zinc acetate dehydrate, monoethanolamine, isopropanole, and de-ionized water, the films were preheated at 225?C for 15 min. The crystallographic structures of ZnO films were investigated using X-ray diffraction (XRD);the result shows that the good film was prepared at dip coating technique, it was polycrystalline and highly c-orientation along (002) plane, the lattice constant ratio (c/a) was calculated at (002), it was about 1.56. The structure of thin films, prepared by spin coating technique, was amorphous with low intensity and wide peaks. The optical properties of the prepared film were studied using UV-VIS spectrophotometer with the range 190 - 850 nm, and by using the fluorescence spectrometer. The optical characterization of ZnO thin films that were prepared by the dip coating method have good transmittance of about 92% in the visible region, it can be noted from the fluorescence spectrometer two broad visible emission bands centered at 380nm and 430 nm. The optical energy gaps for the direct and indirect allowed transitions were calculated, the values were equal 3.2 eV and 3.1 eV respectively. Dip coating technique create ZnO films with potential for application as transparent electrodes in optoelectronic devices such as solar cell.

Structural and Optical Dispersion Characterisation of Sprayed Nickel Oxide Thin Films

Crystalline and non-crystalline nickel oxide (NiO) thin films were obtained by spray pyrolysis technique (SPT) using nickel acetate tetrahydrate solutions onto glass substrates at different temperatures from 225 to 350℃. Structure of the as-deposited NiO thin films have been examined by X-ray diffraction (XRD) and atomic force microscope (AFM). The results showed that an amorphous structure of the films at low substrate temperature (Ts = 225℃), while at higher Ts ≥ 275℃, a cubic single phase structure of NiO film is formed. The refractive index (n) and the extinction coefficient (k) have been calculated from the corrected transmittance and reflectance measurements over the spectral range from 250 to 2400 nm. Some of the optical absorption parameters, such as optical dispersion energies, Eo and Ed, dielectric constant, ε, the average values of oscillator strength, So, wavelength of single oscillator λo and plasma frequency, ωp, have been evaluated.

Effects of heat treatment on morphological,optical and electrical properties of ITO films by sol-gel technique

Indium-tin-oxide(ITO)films were prepared on the quarts glass by sol-gel technique.Effects of different heat treatment temperatures and cooling methods on the morphological,optical and electrical properties of ITO films were measured by TG/DTA, IR,XRD,SEM,UV-VIS spectrometer and four-probe apparatus.It is found that the crystallized ITO films exhibit a polycrystalline cubic bixbyite structure.The heat treatment process has significant effects on the morphological,optical and electrical properties of ITO films.Elevating the heat treatment temperature can perfect the crystallization process of ITO films,therefore the optical and electrical properties of ITO films are improved.But the further increasing of heat treatment temperature results in the increment of ITO films’resistivity.Compared with ITO films elaborated by furnace cooling,those prepared through air cooling have following characteristics as obviously decreased crystalline size,deeply declined porosity,more compact micro-morphology,improved electrical property and slightly decreased optical transmission.

Third-Order Optical Nonlinearities in the Poly(2-Chloro-1,4-Phenylene Vinylene) Thin Film

A new polymer thin film,ploy(2-chloro-1,4-phenylene vinylene)(ClPPV),with high environmental and thermal stability,high optical damage threshold,and good film quality,was successfully prepared by the“precursor-route”method.Its third-order optical nonlinearities were measured by picosecond forward three-dimensional degenerate four-wave mixing technique.In the near resonance region(532nm),the measured third-order nonlinear optical coefficients x(3)zzzz and x(3)yzzy are 9.1 × 10^(-10) and 7.2 × 10^(-11) esu,respectively,and its response time is quite fast,estimated to be less than picosecond.The Kerr effect,which arises from the distortion of the large quasi-one-dimensionalπ-conjugated electronic charge distribution of ClPPV,is the main reason for generating third-order optical nonlinearities.

Structural and Electrical Characterization of GaN Thin Films on Si(100)

The Gallium Nitride (GaN) layers grown on silicon substrates by electron beam evaporation technique. X- ray diffraction revealed that polycrystalline GaN was obtained indicating the enhance crystallinity of the films with annealing temperature at 600oC. Crystalline quality of the GaN films was determined by Scanning Electron Microscopy (SEM). The crystalline size increases with increasing annealing temperature. The fab- ricated MIS structures were characterized using Capacitance-Voltage (C-V) measurements, the capacitance remains nearly constant over a large range in higher negative as well as over a large range in higher positive gate voltages and Current-Voltage (I-V) measurements shows low forward and reverse current possibly due to high density defect formation in the thin layer of gallium nitride during its growth.The film is characterized by X-Ray photoelectron spectroscopy (XPS). The XPS spectra show that formation of pure GaN with- out presence of elemental gallium and Ga2O3 in this film.

Preparation and properties of SrBi_(2.2) Ta_2O_9 thin film

SrBi2.2 Ta2O9（SBT） thin film with thickness of 2μm was successfully prepared by sol-gel method, using strontium acetate semihydrate [Sr（CH3COO）2·1/2H2O] and bismth subnitrate [BiO（NO3）], and tantalum ethoxide [Ta（OCH2CH3）5] as source materials, glacial acetic and ethylene glycol as solvents. The X-ray diffraction（XRD） and transmission electron microscope（TEM） results indicate that SBT layer-perovskite phase obtained has to be single phase, SBT thin film is formed after being annealed at 800℃ for 1min. The typical hysteresis loop of SBT thin film on Pt/Ti/SiO2/Si is obtained, and the measured polarization value of the SBT thin film is 4.2μC/cm2.

Thinning of Emulsion Water-in-Oil Films Stabilized with Modified Aluminum Hydroxide under Influence of Applied Pressure Drop

The results of studies of thinning free water-in-oil emulsion films stabilized by solid particles by the Applied Pressure Drop Technique (APDT) are reported. The quasi-equilibrium film thickness achieved by slow increasing the pressure drop was smaller than the rupture thickness obtained by sharp increasing the pressure. It is shown that non-equilibrium films ruptured with thicknesses corresponding to adjustment of the packing of solid particles in the films. It is supposed that the restructuring package is the cause of the earlier breakthrough of the film.

Synthesis and Electrical Characterization of ZrO2 Thin Films on Si(100)

The ZrO2 thin films deposited on Si (100) were successfully synthesized by solgel process and deposited by using spin-coating technique.The structural properties of ZrO2 thin films were investigated by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and electrical properties were studied by conventional techniques like Capacitance-Voltage (C-V) measurement and Current–Voltage (I–V) measurement. The XRD of ZrO2 films shows the films crystallized and exists in two phases at 700℃ calcinations temperature. The C–V characteristics of all the dielectric films that involved distinct inversion, depletion, and accumulation were clearly revealed in MIS structure. I-V characteristics of ZrO2 thin films on Si shows decreased saturation current on calcinations temperatures. The XPS measurement reveals that a zirconium silicate interfacial layer has formed in the ZrO2/Si Systems.