电极材料对高折射钛钡玻璃光学性能的影响

研究了不同材质的材料对钛钡玻璃光学性能的影响,探讨利用电熔工艺制备高钛钡玻璃珠的可行性。结果表明相对于Al_2O_3,SiO_2更易使钛钡玻璃颜色着色。而金属钼能显著降低钛钡玻璃的透过率,在静态试验中明显变黑。而2%含量的SnO_2对钛钡玻璃的颜色影响有限。考虑到实际侵蚀量更低,因此只要熔制工艺控制适当,能实现钛钡玻璃的电熔化。     

Synthesis,Magnetic Anisotropy and Optical Properties of Preferred Oriented Zinc Ferrite Nanowire Arrays

Preferred oriented ZnFe₂O₄ nanowire arrays with an average diameter of 16 nm were fabricated by post-annealing of ZnFe₂ nanowires within anodic aluminum oxide templates in atmosphere. Selected area electron diffraction and X-ray diffraction exhibit that the nanowires are in cubic spinel-type structure with a [110] preferred crystallite orientation. Magnetic measurement indicates that the as-prepared ZnFe₂O₄ nanowire arrays reveal uniaxial magnetic anisotropy, and the easy magnetization direction is parallel to the axis of nanowire. The optical properties show the ZnFe₂O₄ nanowire arrays give out 370–520 nm blue-violet light, and their UV absorption edge is around 700 nm. The estimated values of direct and indirect band gaps for the nanowires are 2.23 and 1.73 eV, respectively.     

Optical Scattering from Nanostructured Glass Surfaces

Nanostructured glass surfaces enable new and innovative applications for glass substrates. These nanostructures enable trapping as well as extraction of light. They affect the propagation of light such that it scatters and is trapped or extracted based on the index of the propagation media. The diffusive scattering component as opposed to the specular component is what enables the trapping and extraction. Often smooth surfaces are required for growing semiconductor thin films. Scattering sites beneath these surfaces can significantly enhance the optical performance of these films. Example devices utilizing these substrates include organic light-emitting diodes (OLED) displays, OLED lighting components, and microelectromechanical systems reflective displays. We demonstrate methods to fabricate these substrates using nanoparticle deposition processes. Important parameters of these nanoparticles and their agglomerates include both size and refractive index. We characterize these substrates using atomic force microscopy and scanning electron microscopy microscopy, and we simulate their optical properties using optical scattering models.     

Electrocatalytic Reduction of Nitrate on Activated Rhodium Electrode Surfaces

Electrodeposited rhodium films on titanium substrates have been electrochemically activated to produce a high area surface with a specific activity for nitrate electroreduction directly to N₂. The activation process involves oxidation/reduction cycles in an alkaline, KCl electrolyte containing nitrate ions. Surfaces of up to 230 times the geometric area are achieved, together with a surface morphological modification. While the active surface, once formed, is intrinsically unstable during long-term nitrate reduction, its activity can be maintained in situ by an electrochemical cycling procedure. The high area rhodium has the form of a nano-structured sponge, with a surface area of ca. 19 m² g^–1. The morphological modification is evidenced by a change in the hydrogen UPD structure, changes in the surface redox behaviour associated with OH adsorption, and a reduction in the activation energy for nitrate reduction from ca. 47 to 20 kJ mol^–1. The reduction in activation energy, however, is accompanied by a decrease in the pre-exponential factor, and this apparent compensation effect results in similar rate constants on the activated and unactivated surfaces. The enhancement in the catalyst's activity for nitrate reduction results from an increase in the relative activity of nitrate reduction over water reduction. The activated catalyst sustains steady state nitrate reduction at an increased over-potential before the reaction to N₂ decays, and hydrogen evolution and reduction to ammonia take place. The presence of nitrate ions is essential for the formation of the active surface, and specifically adsorbed nitrate ions and reductive intermediates are present at the surface when it is reformed. A mechanism for the elementary surface reaction steps involved in nitrate reduction, and the apparent habit growth of the active surface phase in the nitrate containing solution is discussed.     

Investigation of the Electroadhesion Properties of Modified Polymer Surfaces

The effect of modification of the PTFE film surface on its adhesion and on mechanoelectron emission has been studied. If previously treated in glow discharge, PTFE gains significant adhesion strength up to the value 200 kg. per sq. sm. The increase of the adhesion strength is due to free peroxy radicals of the activated PTFE surface. The disjunction of the contact (treated PETF-polyepoxide) gives rise to emission with electron energies of 40 kev and initial intensity of 10⁴ imp/sec. It becomes possible to vary the electroadhesion properties of treated surfaces through reactions of free peroxy radicals of activated surface with diverse reagents. The adhesion strength and emission intensity depend on the nature of functional groups on the surface. There is a correlation between the adhesion strength and emission intensity for different modified surfaces. These results are in a good agreement with the electronic theory of adhesion, the strength of adhesive joint depending on the charge density of the electric double layer, produced by collective donor-acceptor interactions at the interface. The acceleration of electrons in high electric fields in gaps formed on breakdown of adhesion contact accounts for phenomena of high energy electron emission in vacuum. Intensity of the post-emission from freshly-formed breakdown surfaces is a function of time. Mechanoemission is considered to be a type of autoelectron emission, caused by the residual charge field of freshly formed surface.     

Investigation of the Electroadhesion Properties of Modified Polymer Surfaces

The effect of modification of the PTFE film surface on its adhesion and on mechanoelectron emission has been studied. If previously treated in glow discharge, PTFE gains significant adhesion strength up to the value 200 kg. per sq. sm. The increase of the adhesion strength is due to free peroxy radicals of the activated PTFE surface. The disjunction of the contact (treated PETF-polyepoxide) gives rise to emission with electron energies of 40 kev and initial intensity of 10⁴ imp/sec. It becomes possible to vary the electroadhesion properties of treated surfaces through reactions of free peroxy radicals of activated surface with diverse reagents. The adhesion strength and emission intensity depend on the nature of functional groups on the surface. There is a correlation between the adhesion strength and emission intensity for different modified surfaces. These results are in a good agreement with the electronic theory of adhesion, the strength of adhesive joint depending on the charge density of the electric double layer, produced by collective donor-acceptor interactions at the interface. The acceleration of electrons in high electric fields in gaps formed on breakdown of adhesion contact accounts for phenomena of high energy electron emission in vacuum. Intensity of the post-emission from freshly-formed breakdown surfaces is a function of time. Mechanoemission is considered to be a type of autoelectron emission, caused by the residual charge field of freshly formed surface.     

Synthesis and Optical Properties of Nonlinear Optical Polyarylates

Several polyarylates based on bisbenzylidenoketones have been synthesized by interfacial polycondensation. Two distinct types of polymers have been obtained: guest-host systems and polyarylates with NLO (nonlinear optical) side chains. The dispersion of the linear refractive index (n ₀) is measured over the wavelength range from 800 to 2000 nm. The Holing formula, based on a semiclassical model of a simple harmonic oscillator, is used to calculate the NLO susceptibility X⁽³⁾.     

Anisotropy of Mechanical Properties of Zirconia-Based Ceramics Tested for Bending

The effect of bending stress s of different magnitudes and signs on the fracture toughness K _1c of polycrystalline specimens of partially stabilized zirconia (PSZ) is considered. A method for testing pre-stressed PSZ specimens by Vickers indentation using a four-point bending scheme is proposed. The dimensions of the impression from a diamond pyramid and the length of the radial cracks generated thereby are determined. An anisotropy of strength properties is revealed in the specimens tested, which is explained by the involvement of two mechanisms: forcing action of an external stress on the crack opening and activation of the tetragonal- monoclinic phase transition in the tensile stress field.     

Enhanced Optical Transmittance by Reduced Reflectance of Curved Polymer Surfaces

Subwavelength nanostructure arrays on surfaces improve their optical transmittance by reducing the reflection of light over a wide range of wavelengths and angles of incidence. A method to imprint a sub‐100 nm nanostructure array on a large surface (Ø 20 mm) made from thermoplastic materials is reported. Transmittance through the flat polymer is improved by ≈6.5%, reaching values of up to 97.5%, after imprinting. The optical properties of the nanostructured samples are highly reproducible. After eight repeated imprinting operations with the same stamp, the transmittance of the nanostructured surface is decreased by less than 0.2%. Moreover, the nanostructures can also be imprinted on curved polymethylmethacrylate surfaces, achieving a maximum transmittance of 97%. This method to prepare large‐scale antireflective nanostructures on flat and flexible curved polymer surfaces is of interest for the production of antireflective screens, optical devices, and biomedical devices such as contact lenses and intraocular lenses.

     

Optical Detection of Particle Contamination on Surfaces: A Review

This paper reviews the application of light scattering to the detection and measurement of discrete contaminating particles on smooth surfaces. The optical properties of specular and diffuse reflecting surfaces, and those of isolated particles are summarized, followed by the behavior of surface-deposited particles. A discussion is presented on the parameters influencing the detectability of particles on surfaces, and the principal design criteria of light scattering inspection systems. Emphasis is placed on laser scanning systems which, at present, predominate as a versatile means of automated surface contamination detection. Both laser scanning and video inspection systems are discussed, and examples are presented of typical commercially available instruments incorporating these techniques.     

Theoretical Investigation of Acid-Base Properties of Oxide Surfaces

We analyze the acid-base strength of oxide surfaces, in the light of quantum calculations of proton and hydroxyl group adsorption on oxides presenting a wide range of ionicities and surface orientations. The parameters which determine the values of the charge transfers, adsorption energies and structural properties of surface OH groups are discussed and related to the indicators generally used to quantify acid-base reaction strength in adhesion science, heterogeneous catalysis and colloid physics.     

二氧化铅电极的制备及其性能研究

在钛基体上利用电沉积技术制备二氧化铅电极,研究了溶液组成与电沉积工艺参数对电极制备的影响,确定了最佳工艺条件.采用加速电解寿命测试研究了二氧化铅电极在硫酸溶液中的稳定性,试验表明电极寿命可达35h.用该电极对100mg/L甲基橙的模拟废水处理1h,脱色率可达到95.3%.     

Electrode Properties of Fluorine-Containing Alkali Silicate Glasses

An attempt is made to change the electrode properties of alkali silicate glasses containing various glass-formers and modifiers by introducing fluorine components into their compositions. Model systems with the initial hydrogen and metallic electrode functions are investigated. The study is based on the assumption that new ionogenic structural units with a mixed-anion constituent are formed in the glass structure. Lithium, sodium, and potassium silicate glasses with different fluorine contents are synthesized. Their potentiometric properties are studied. It is shown that the introduction of fluorine exerts the strongest effect on the electrode properties of alkali aluminosilicate glasses. An indirect corroboration is obtained for the assumption that strongly acid groupings containing fluorine can be formed in the glass network. It is found that the technological properties of the electrode glasses are significantly improved and the chemical durability in the potassium-containing system also becomes much higher. From the results obtained, the inference is drawn about the prospects of fluorine introduction into electrode glasses.     

Optical Properties of Diatomic Glasses

The ability of elements to form glasses, the leading part played by the elements of Group VI (O, S, Se, and Te), and the possible influence of the elements of Group VII (F, Cl, Br, and I) are discussed. New glasses suggested by previous work were melted and the refractive index ( n ) and coefficient of dispersion ( v ) of some of them were measured. Inspection of the n, v plots of oxide, sulfide, selenide, and telluride glasses shows that the area corresponding to them extends toward high values of refractive index ( n _max= 5.3) and low values of dispersion coefficient ( v _min=4).     

Optical Properties of GaSb Nanofibers

Amorphous GaSb nanofibers were obtained by ion beam irradiation of bulk GaSb single-crystal wafers, resulting in fibers with diameters of ~20 nm. The Raman spectra and photoluminescence (PL) of the ion irradiation-induced nanofibers before and after annealing were studied. Results show that the Raman intensity of the GaSb LO phonon mode decreased after ion beam irradiation as a result of the formation of the amorphous nanofibers. A new mode is observed at ~155 cm^-1 both from the unannealed and annealed GaSb nanofiber samples related to the A_1g mode of Sb–Sb bond vibration. Room temperature PL measurements of the annealed nanofibers present a wide feature band at ~1.4–1.6 eV. The room temperature PL properties of the irradiated samples presents a large blue shift compared to bulk GaSb. Annealed nanofibers and annealed nanofibers with Au nanodots present two different PL peaks (400 and 540 nm), both of which may originate from Ga or O vacancies in GaO. The enhanced PL and new band characteristics in nanostructured GaSb suggest that the nanostructured fibers may have unique applications in optoelectronic devices.     

Electrochemical Properties of Hydroxyapatite Crystal Surfaces on Anatase Photocatalysts

Hydroxyapatite (HAp) was crystallized on anatase titanium dioxide (TiO₂) photocatalytic crystals or their thin films using of a pseudo-body solution method, and electrochemical properties of the HAp-adhered anatase TiO₂ photocatalytic surfaces were discussed. Decomposition rates of methylene blue were faster for the HAp-adhered anatase TiO₂ photocatalysts, although specific surface areas were smaller than those for the commercial anatase TiO₂ ones. Surface potential dispersions on the HAp-adhered anatase TiO₂ thin films before and after an ultraviolet light irradiation were measured by an atomic force microscopy. Changes in the color of leucocrystalviolet mixed in the HAp-adhered anatase TiO₂ photocatalysts or the commercial anatase TiO₂ ones with experimental durations were compared. Movements of electrons from the anatase TiO₂ photocatalytic surfaces to the HAp, crystals and oxidizing reactions on the HAp-adhered anatase TiO₂ photocatalytic surfaces in the dark were discussed on the basis of these experimental results.     

锂离子电池电极性能的改进

负极材料对于可充电锂电池的容量和提高和循环性能的保证具有重要的意义。通常用于可充电锂电池的负极材料有碳类（如石墨、软碳、硬碳等）、金属氧化物、金属硫化物等。其中,尤以石墨等材料的技术比较成熟,综合性能优良、价廉易得;而其它材料则存在一定问题,尚处于研究阶段。但实际使用与研究表明,可充电锂电池所用的石墨负极材料首次不可逆容量损失较大,首次充放电效率低。这是目前可充电锂电池存在的缺点,影响了其功能的发挥。     

Optical Properties of Polymer-dispersed Liquid Crystals

Abstract

Electrooptical properties of polymer-dispersed liquid crystals (LCs) are analyzed from the point of view of the order created by the electric field, dynamic changes of the order (orientation) parameter, and optical transmittivity. Optical phase retardation causes an optical phase shift and is related to thermal effects. Nonlinear optical properties are investigated from the point of view of self-transparency, nonlinear gratings, threshold degenerate wave mixing, optical bistability and second harmonic generation.     

Optical Properties of Carbon-Containing film Composites

It was found that the structure of FC carbon filler significantly affects transmission and reflection of IR radiation. The penetrating power of FC is higher the more ordered the structure of the filler. The lowest transmission of IR radiation is observed in FC with a filler characterized by a macropore structure; microporosity has almost no effect on the penetrating power of FC. The carbon filler significantly affects the reflectivity of FC in the IR region: the intensity of reflection of carbon-containing film materials is one order of magnitude less than for films with no filler. The reflectivity of FC is higher the more perfect the structure of the carbon-containing filler is.     

Anisotropy of Mechanical Properties in a Hot‐Pressed Boron Carbide

Effects of microstructure and material properties on the mechanical behavior of hot‐pressed boron carbide are presented. The microstructure and intrinsic microstructural inhomogeneities have been characterized using scanning electron microscopy characterization techniques (SEM/EDS/EBSD). In situ mechanical characterizations of the boron carbide microstructure and its larger inhomogeneities have been performed by nanoindentation. Macroscopic dynamic and quasi‐static compressive responses have been studied in two characteristic orientations (parallel and perpendicular to the hot‐pressing direction) using a modified compression Kolsky bar setup (strain rates of /s) and standard MTS test machine (strain rates of /s). The microstructure characterization showed that boron carbide has a fine‐grained microstructure with a complex superposition of nonmetallic inclusions, such as free carbon, AlN, and BN. Nanoindentation tests conducted in three principal planes of the plate revealed an anisotropy of the mechanical properties. The compression tests revealed that the strength of this hot‐pressed boron carbide is orientation dependent. Detailed SEM analysis indicated transgranular fracture and microcracking originating at large carbon inclusions. Influences of microstructural anisotropy on the mechanical response of the material are discussed.