Applied Mechanics and Materials Vols. 217-219

Abstract: Carbon black (CB) filled polypropylene composites were prepared, with CB modified by coupling agent. Three phenomena could be observed during the course of the magnetostrictive properties measurement. The first was that a relative large magnetostriction of 115ppm, comparative with that of metallic material, was obtained. The second was that the magnetostriction was strongly dependent on magnetic intensity and time interval. And the third was that obvious hysteresis effect appeared which was seldom found for material of Tb_xD_1-xFe_2-y thought as typical magnetostritive material.

Abstract: High after-grow intensity with controllable morphology SrAl₂O₄: Eu, Dy phosphors were synthesized by an innovative combustion-melted-salt-assistant-Sol-Gel (CMSASG) method, by using Oxides, Carbonate, Nitric acid, Polyethylene glycols and Urea as raw materials, Gel-forming at 100°C, Combustion under 450°C, Melted-salt-calcination at 1250°C. The luminescent intensity and after-grow intensity of the SrAl₂O₄: Eu, Dy phosphors with the suitable pair-dope synthesized by CMSASG method are higher than those of commercial samples. The size of the phosphor with excellent luminescent characteristics and shape of sphericity or near sphericity synthesized can be controlled from about 200 nm to 10 μm.

Abstract: The structure stability、micro-structure and electrical properties of lithium doping on potassium sodium niobate ceramics (Na0.5K0.5)NbO3 (NKN) were investigated in this study. Solid oxide mixing method with post calcination and sintering was employed to fabricate(Na0.5K0.5)(1-x) LixNbO3 ceramic. Lithium oxide was adopted as the sintering aids. For Li doping x=6 mol% in (Na0.5K0.5)(1-x) LixNbO3 ceramic a optimal crystallization and electrical properties could be achieved after 650°C calcination and 1060°C sintering. Ferroelectric properties of the lead-free ceramic behaved a coercive field of 12.5kV/cm and remanent polarization as high as 30uC/cm2.

Abstract: The development of CdTe/CdS solar cells on flexible substrates is reviewed in this article. Photovoltaic structures on lightweight and flexible substrates have several advantages over the heavy glass based structures in both terrestrial and space applications. The cells mounted on flexible foil are not fragile, the requirements of the supporting structures are minimum and they can be wrapped onto any suitably oriented or curved structures. The specific power of the solar cells is an important factor in space applications and hence development of photovoltaic devices on light weight substrates is interesting. CdTe is one of the leading candidates for photovoltaic applications due to its optimum band gap for the efficient photo-conversion and robustness for industrial production with a variety of film preparation methods. Flexible solar cells with conversion efficiencies exceeding 11% have been developed on polyimide foils. The development of CdTe devices on metallic substrates is impeded due to the lack of a proper ohmic contact between CdTe and the substrate. The polymer substrate has the advantage that the devices can be prepared in both “superstrate” and “substrate” configurations.

Abstract: This paper considered that putting the specialized soft magnetic material in the permanent magnetic field with a particular structure and the magnetic field strength can make it be magnetized, finally the surface of the soft magnetic material will produce twice strength than that of original permanent magnetic field. And we made a analysis for said phenomenon. We introduce d the deironing machines of permanent magnet strong magnet and high-gradient permanent magnet which are manufactured based on this principle. They can effectively remove the iron mineral of "kaolin" and its principles and structure is simple but it has the advantages of high efficiecy, energy saving, environmental protection. So it provides important references to chemical industry, ceramics and other industries which apply kaolin technologies.

Abstract: The thin films of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH- PPV) used as photoactive layer in organic photovoltaic cells were prepared on glass substrates by the spin-coating technique. The transmittance spectra of thin films were measured by a double beam spectrophotometer. The optical constants such as refractive index and extinction coefficient of the thin films were determined from the measured transmittance spectra using the method of whole optical spectrum fitting. The complex dielectric constant and the complex optical conductivity of the thin films were obtained. In addition, the optical bandgap of the thin film were calculated according to the Tauc's law. The results show that the thin films exhibit direct allowed transitions and the optical bandgap is about 2.18 eV. These results provide some useful references for the design and optimization of device structure in organic photovoltaic cells.

Abstract: In order to utilizing the light flux reasonably and effectively, the LED reflector which is designed according to light reflection principle, makes the light emitted from LED resource spread in a specific direction through reflection. The problems about LED oblique illumination are described in the paper. By comparing the optical properties of elliptical and parabolic and using the optical modeling software, a compound trough reflector is designed. The irradiance map of optical simulation shows that a uniform rectangular spot is shaped on the lighting plane and the optical efficiency reach up to 72.3％.

Abstract: Fe/In₂O₃ magnetic granular films have been prepared by radio frequency sputtering (rf) method. The results reveal that the nanometer-sized Fe grains uniformly disperse in the amorphous matrix In₂O₃ for the as-deposited samples. At room temperature, the Fe_0.35/(In₂O₃)_0.65 film shows a superparamagnetic behavior and 5.2% magnetoresistance (MR) ratio is obtained. The susceptibility measurements manifested that the blocking temperature is 50 K. Blow a certain freezing temperature Tf about 10K, the film transits from ferromagnetic state to a composite-cluster state in which the Fe atoms dispersed randomly in In₂O₃ severs as intermedia to couple the Fe grains together. In this case, the MR ratio of the film increases dramatically and a maximum giant magnetoresistance (GMR ) ratio up to 82.4% is obtained at 2.2 K, which is quite different to the MR effect at room temperature. The mechanism of this GMR is attributed to the increase of the hopping mobility of carriers under the applied magnetic field.

Abstract: A simple quantitative model is developed to understand the origin of the photoluminescence (PL) behavior of carbon dots. The sp² fraction and size depend on the energy gaps in carbon dots containing a mixture of sp² and sp³ bonding. The finite-sized molecular sp² domains within the carbon-carbon and carbon-oxygen sp3 matrix behave as the luminescence centers and when they are opposed to the surface of carbon dots, surface passivation by organic molecules is required for preventing the occurrence of nonradiative recombination. According to our calculations, highly efficient and tunable PL from carbon dots can be achieved by controlling the nature of sp² sites.

Abstract: The light delivery system is an important component in heat-assisted magnetic recording technology. It needs a light source and delivery the laser beam to the slider for writing process. However, the different designs lead to the different manufacturing processes, number of process steps and technologies consequently affect to the fabrication cost. This paper aims to propose an alternative design for a light delivery system. The complicated processes to manage a heat in a manufacturing are also take into account to have the final product meets the requirement for HAMR technology. The components are also fabricated which is made for a design and also presented.