Advanced Materials Research Vol. 1058

Abstract: The metallization of polymer microsphere has attracted attention in recent years due to its wide range of technological applications. In this study, chemical etching with concentrated sulfuric acid and potassium dichromate bichrome (K₂Cr₂O₇) was used to prepare acrylic resin microspheres’ surfaces for high polymer/metal adhesion. Meanwhile, the influence of etching time and temperature on the surface morphology of electroless nickel plated acrylic resin microsphere was investigated. The optimal etching process conditions were identified in this test as follows: etching temperature of 70°C and etching time of 60 ~ 90min. Specular reflection FTIR and scanning electron microscopy was employed to observe the morphology of the nickel plated films and the Ni/polymer interfacial structures. As the results shown, the effect of etching process conditions on the coating thickness and the surface topography of the film was obviously.

Abstract: In actual measurement of particle size distribution by the Shifrin-transform, many noises are easily misread as distribution peaks, and bring serious difficulties to the measurement. The purpose of this paper is to find a method of removing these noises to improve existing technology. By analyzing the source of these noises, we found these noises are mainly caused by the serious large angle data loss, and then propose a compensation function in the Shifrin-transform to remove these noises. Simulations explain that the method has a good effect. The method is actually tested for the sample particles of the unimodal and bimodal distribution by experiments. The result shows that the noises disappear but the number and location of original distribution peaks aren’t affected after using the compensate function. So this method can remove effectively noises and restore accurately original distribution in the measurement.

Abstract: In the present work we report on the Single-crystal samples synthesis of type-VIII clathrates Ba₈Ga_16−xCu_xSn₃₀ (x = 0, 0.75, 1, 1.5, 2) by the Sn-flux method and the effects of Cu doping Ba₈Ga₁₆Sn₃₀ have been investigated using x-ray photoemission spectroscopy (XPS). The structural and electronic properties have been studied by first-principles method based on the density-functional theory. We found that the Cu doping induced rearrangement of host-cage configuration, and consequently change of the electron transport properties. It was found that the binding energies for the Ba₈Ga_16−xCu_xSn₃₀ series decrease with increasing Cu substitution, resulting in a decrease of stability. Calculations indicate that these alloys are all indirect gap semiconductors and the band gap increases with increasing Cu content. Theoretical results indicate that Cu doping Ba₈Ga_16−xCu_xSn₃₀ should be p-type semiconductors, which does not agree with the previous experimental results.

Abstract: First-principles plane wave pseudopotential method based on the density functional theory is used to study of the evolution rule of the optical properties and electronic structure for ZnO tetragonal phase under different pressure. The results show that the chemical bond between zinc and oxygen is shortened with the increase of the external pressure, while the increase of orbital hybridization between the zinc atom and the oxygen atom. The calculations also show that the band structure of ZnO tetragonal phase changes with the increase of the pressure, and the band gap is broadened, which causes that the optical absorption margin and the optical absorption peak move to the direction of high energy.

Abstract: Considering that Ca²⁺ has the similar ion radius and the substituted ability as Sr²⁺ and Ba²⁺ but the same family, Ca_xSr_1-x-yLa_yO•nFe_(2n-z)/nCo_z/nO₃ ferrites have been synthesized by the conventional ceramic process. Structure and magnetic properties of Ca_xSr_1-x-yLa_yO•nFe_(2n-z)/nCo_z/nO₃ compounds have systematically been investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM) and B-H hysteresis curve measurements. Several compositions are selected to investigate the formation of M phase with the joint replacement of Ca-La-Co. It is found that the formation mechanism is based on the replacement of Sr²⁺ by La³⁺ plus Ca²⁺ and the charge compensation by Co²⁺. In futher results, the unexpectedly intrinsic coercivity of 436 kA/m and residual flux density of 0.445 T were obtained. In terms of material preparation, we believe that Ca_xSr_1-x-yLa_yO•nFe_(2n-z)/nCo_z/nO₃ is effective in the production of future high energy permanent magnets.

Abstract: The total energy, the electronic properties, phase transitions, and elastic properties of Cu₂ZnSnS₄ (CZTS) in the three structures are investigated by first-principles calculations based on density functional theory. Results show that the total energies of stannite (ST) and primitive-mixed CuAu (PMCA) structures are higher than that of kesterite-type (KS), and the KS is the ground state structure. Relationships between enthalpy and pressure of the KS, ST and PMCA structure of CZTS are also investigated at 0 K, since the pressure can have profound impacts on the electronic structure, possible phase transitions and structure stability. And results also show that KS structure is always the most stable; ST is the second; and the PMCA structure is the most unstable; phase transitions of three structures could not occur in high pressure. The high ratios of shear modulus to bulk modulus (G/B) indicate that CZTS compounds in three types have ductile behaviors. The Poisson ratios for the three structures are from 0.27 to 0.31, which again proves that all structures of CZTS have better plasticity. The results can increase more hints about further research directions, and these effects can play an important role in future experimental preparation technology and theoretical work of CZTS materials.

Abstract: CaF₂ could be used as inner protection liner material of the cavity which is chemical etched by H₂O and HF. This is because CaF₂ is not easy deliquescence, corrosion resistance and self-lubricating properties. This paper mainly analysis and research the three kinds of powder form different manufacture factory. The powder is burned in the air at 1360°C for 0.5h, the result display that the density of block we get after a powder is burned is the biggest and the width of the peak gets narrow after were calcined, which indicates the crystallinity has improved. The powder did not react with water at 90°C,but the powder was burned react with water at 90°C。

Abstract: Computations by density functional theory (DFT) method were performed on a series of di-s-tetrazine derivatives with different substituents and linkages. The heat of formation (HOF) was predicted by designed isodesmic reaction. The results illustrated that introductions group –N₃ or –N=N– could augment the HOF extremely. The crystal structures were obtained by molecular mechanics methods with dreiding force field. Detonation performance was evaluated by using the Kamlet-Jacobs based on the calculated density and HOF. It was found that –ONO₂, –NF₂, –NH–NH– and –N=N– groups were effective to enhance the detonation performance of these derivatives. Seven compounds were screened as the potential candidates for high energy density materials.

Abstract: Thermogravimetry (TG-DTA) method was used to study the heat resistance properties and the thermal decomposition kinetics of the aromatic amine-terminated polyurethane (ATPU)/Epoxy Resin System (E-44) which includes both flexible chains and rigid structural units. The results indicate that the decomposition temperature of the cured ATPU-2/E-44 is higher than that of the cured ATPU-1.5/E-44, and thermal decomposition residual of cured ATPU-2/E-44 is higher than that of cured ATPU-1.5/E-44 system. These results denote that the cured ATPU-2/E-44 has better heat resistance. The results of decomposition kinetics showed that the decomposition reaction activity of the ATPU-2/E-44 system is higher than that of ATPU-1.5/E-44.

Abstract: Magnetotransport properties are investigated in two-dimensional electron gas (2DEG) of AlGaN/GaN heterostructure, including the Drude conductance, the Shubnikov-de Haas (SdH) oscillations and the change with temperature, the electron-electron interaction (EEI) and the change with temperature, the weak antilocalization (WAL) and the change with temperature etc.