Advanced Materials Research Vols. 846-847

Abstract: CIP particles first have been coated with SiO₂ shell by a Stober process , then grafted the polyaniline by in-situ polymerization to prepare CIP/SiO₂/PANI core-shell composites, and the composites are composed the dielectric loss properties with the magnetic loss properties. It is observed that PANI are on the surface of CIP/SiO₂ particles from the SEM image, XRD patterns further confirm that the CIP/SiO₂/PANI composites are synthesized successfully. In comparison with CIP, the complex permittivity of CIP/SiO₂/PANI composites have certain enhancement in 8-12 GHz frequency range, but it has a very small impact on the complex permeability. On the basis of the Electromagnetic Wave Absorbing Theory, the composites could prepare high-performance absorbing coating based on λ/4 type design, and the coating is below-10dB in the whole X-band, which could be used for architectural space electromagnetic radiation protection.

Abstract: High-purity Li₂CO₃ was purified and prepared by carbonation decomposition method using industrial Li₂CO₃ as raw material. The effects of carbonation temperature on the purity, productivity and the removal of impurities containing Ca, Mg, Fe, Cu and Ni in purification process were investigated. The results shown that high carbonation temperature didnt benefit the purity and productivity of Li₂CO₃. The content of Mg decreased with the increase of carbonation temperature. The other impurities, such as Ca, Fe, Cu and Ni, had no obvious change with the increase of carbonation temperature. The optimum carbonation temperature was determined as 25°C.

Abstract: In recent years, the development of thin film materials has been applying widely in various fields. ZnO has many advantages Compared with GaN, which is based on wide band gap semiconductor material and also the most successful technology currently. ZnO is a kind of thin film materials with development potential in high technology field and civil field. Based on the current study of functional thin film materials, this paper introduces the main physical method of preparation in ZnO thin film, focusing on method of ZnO thin films preparation by sol-gel, and summarizes.

Abstract: The electronic-energy band structure and optical properties of SrTi_0.5Zr_0.5O₃ are calculated by the pseudo-potential plane wave (PP-PW) mehod with the generalized gradient approximation (GGA). The energy band structure, density of states (DOS) are obtained. The optical properties including the dielectric function, reflectivity, absorption spectrum, extinction coefficient, energy-loss spectrum and refractive index are also discussed.

Abstract: The electronic-energy band structure and optical properties of BaTi_0.75Nd_0.25O₃ are calculated by the pseudo-potential plane wave (PP-PW) mehod with the generalized gradient approximation (GGA). The energy band structure, density of states (DOS) are obtained. The optical properties including the dielectric function, reflectivity, absorption spectrum, extinction coefficient, energy-loss spectrum and refractive index are also discussed.

Abstract: Based on first-principles method of density functional theory, the electronic structures and absorbing properties of pure ZnO system and Co doped ZnO have been calculated. Meanwhile, the relationships between electronic structures and absorbing properties are investigated. The results show that the absorbing properties of Co doped ZnO improved significantly compared to pure ZnO system. Absorption frequency peak moves to low frequency and two absorption band appear at 425.6nm and 802.7nm, combining the absorbing properties of experimental results of Co-doped ZnO. The theoretical results have offered theoretical data for the designing and application of of ZnO which is a new type of wave absorbing material and is subjected to an extensive concern. Meanwhile, the calculated results also enable more precise monitoring and controlling during the growth of ZnO material.

Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60 meV).Based on first-principles spin-density functional calculations, the electronic structures and reflectivity of pure ZnO have been calculated. We find that theory calculated peaks basal consistent with the experiment results. The absorbing properties of Ni doped ZnO have also been calculated and the relationships between electronic structures and absorbing properties are investigated. The results show that the absorbing properties of Co doped ZnO improved significantly compared to pure ZnO system. Absorption frequency peak moves to low frequency and one absorption band appear at 1236.9nm.The theoretical results have offered a direction for the designing and application of ZnO which could lead to lasing action based on exciton recombination even above room temperature.

Abstract: The electronic structure, including band structure, density of states ( DOS) and optical properties of SrTi_0.5Nb_0.5O₃ are calculated from the first principles of plane wave ultra soft pseudo potential technology. The calculated results reveal that due to the electron doping, the Fermi level moves into the conduction bands and the system shows metallic behavior. The optical properties are also discussed in detail.

Abstract: The DC power substation equipment is all energy infrastructure, once therere some problems with the DC equipment, which will make all the related equipment loses power, it will directly affect the safe operation of the substation. This article discusses some shortcomings of the original lead-acid batteries for emergency DC power, demonstrated high frequency switching power supply with the combination used of LiFePO4 iron group of science, along with a brief description of the features and benefits of their work.