Advanced Materials Research Vols. 335-336

Abstract: Ln(Mg_0.5Ti_0.5)O₃ (Ln=La, Nd, Sm) powders were prepared by polymeric precursor method. After calcined at the temperature range of 600 °C to 1300 °C, the powders were characterized by XRD, SEM and FT-IR. The results indicated that Ln(Mg_0.5Ti_0.5)O₃ perovskite crystal phases were formed when the precursor powders were calcined at 800 °C and the crystallization of Ln(Mg_0.5Ti_0.5)O₃ powders increased gradually with the increasing calcining temperature.

Abstract: A novel complex [Ru(phen)₃][Cu(opba)]‧6H₂O has been prepared and characterized structurally. The crystal structure showed that the complex consisted of dication [Ru(phen)₃]²⁺ and complex dianion [Cu(opba)]^2–. The IR, Uv-vis, EPR spectra were studied, and EPR spectra showed hyperfine structure from copper isotopes ⁶³Cu and ⁶⁵Cu, and superhyperfine(shf) from ¹⁴N coupling, giving parameters g// = 2.207，g = 2.026，A//^Cu = 196 G，A^Cu = 43 G，A//^N = 13 G，A^N = 17 G. The bond parameters were evaluated based on the EPR spectra, indicating substantial π-bonding character in the Cu–N and Cu–O bonds in the complex [Cu(opba)]^2–. The spin density on nitrogen and oxygen atoms is 0.081 and 0.195, respectively.

Abstract: The nanosize magnetic particles were synthesized by thermal decomposition method with size distribution in the range of 10 ~ 30 nm. Different category and quantity of surfactants were used modifying the surface of the synthesized nanoparticles to control the particles’ shape and size. Multi-shapes, such as uniformity cubic, mixture of spherical and cubic, and the similar chick footmarks, were acquired in our experiment by different surfactants. It indicates the surfactant is a key factor for the size and shape of particles. The surfactants of PVP and oleylamine made the particle shape be uniformity cubic; However, the particle partly behaved as spherical shape in the case of using PVP and oleic acid as surfactants.

Abstract: The sintering behaviors and microwave dielectric properties of the Ca_0.6La_0.8/3TiO₃-Li_0.5Nd_0.5TiO₃ (abbreviated CLLNT) ceramics doped by small amounts of ZnO-B₂O₃-SiO₂ glass were investigated in this paper. The adding of ZnO-B₂O₃-SiO₂ glass improved the densifications of the CLLNT ceramics and the sintering temperature of the CLLNT ceramic had been efficiently lowered to 1050°C. Especially, the 8wt% ZnO-B₂O₃-SiO₂ glass doped CLLNT ceramic sintered at 1050°C for 3 h has optimum microwave dielectric properties of Kr=89, Q×f=1445GHz, and TCF=11.4 ppm/°C and it should be a suitable candidate for LTCC applications.

Abstract: A facile chemical approach of preparing magnetic Fe₃O₄ nanoparticles with controlled sizes was developed by microwave-assisted co-precipitation method. By changing the synthetic conditions, particle diameter can be tuned from 9.6 to 19 nm. The results indicate that the hydrothermal temperature (HT) and consequent aging time play important roles in controlling of the particle size and crystallization.

Abstract: Transparent conducting ZnO:Zr thin films were deposited on glass substrates by DC reactive magnetron sputtering in Ar+O₂ ambience with different Ar/O2 ratios. The structural, electrical and optical properties of ZnO:Zr films were analyzed by X-ray diffraction, four-point probe measurements and UV–vis spectrophotometers. When Ar/O₂ ratio increases from 20:1 to 25:1, the resistivity significantly decreases because of the improvement of the crystallinity. However, with further increase in Ar/O₂ ratio, the crystallinity begins to deteriorate resulting in an increase in the resistivity. The films deposited at the optimum Ar/O₂ ratio of 25:1 have the minimum resistivity of 1.4×10^-3 Ω•cm and a high transmittance of above 92%.

Abstract: (1- x) K_0.5Na_0.5NbO₃ – x BiFeO₃ lead-free piezoelectric ceramics were prepared by the conventional ceramic processing. The compositional dependence of the phase structure and the electrical properties of the ceramics were studied. A morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases was identified in the composition range of x = 0.01. The ceramics exhibit a strong compositional dependence and enhanced piezoelectric properties. The ceramics with 0.6 mol.% BF exhibit good electrical properties (d₃₃ ～146 pC/N, kp ～51%, Tc ～405°C, To-t ～185 °C, εr ～432, and tan θ～ 4.60 %. The related mechanism of the enhanced electrical properties of the ceramics was also discussed. These results show that the air-sintered (1−x) KNN− x BF (0.006 < x < 0.01) ceramic is a promising lead-free piezoelectric material.

Abstract: Light-weight radar absorbing material (RAM) based on resistive frequency selective surfaces (FSS) was designed and prepared. The principle of the resonances of the RAM was analyzed by calculating the impedance of the FSS and the grounded substrate according to the equivalent circuit method, and the results show that a wideband absorbing structure can be gained by producing two adjacent resonances. After design and optimization by Genetic Algorithm (GA), the RAM with absorbing bandwidth of 7.5~18GHz below -10dB was obtained, whose thickness is only 3mm. The designed RAM was gained by preparing resistive patches on the grounded dielectric substrate of rigid polyurethane foam using screen painting technology. The density of the absorber is only 0.2g/cm³, the reflectivity was measured and it shows that the experimental result is consistent with the design one.

Abstract: Eu³⁺ doped LaF₃-SiO₂ nano-composite material were synthesized by sol-gel method at room temperature, and the structure and properties were characterized by XRD, TG-DTA, IR, excitation and emission spectrum. The structure indicated that the optimal doping formula for preparing nano-materials was La₅Si₉₅ that transformed into a stable mineral structure of cerium fluoride, and mainly found Si-O-Si bonds when the temperature was above 500 °C. Luminous property researches showed that the optimum annealing temperature was 500 °C. The best excitation wavelength was 395 nm when the monitoring wavelength was 612 nm, and the optimal doping molar concentration of Eu³⁺ was 0.35 mol %.

Abstract: Health assessment is one of the key technologies for civil aircraft health management system. In order to access the health status of components, subsystems and systems of civil aircrafts, this paper explicitly defines the health status, and presents the fuzzy synthetic evaluation algorithm. Then the model of the evaluated object is established to get the health status of quantitative level. Finally, the method is used for health assessment of aircraft hydraulic pump .The results of simulation show the practicability of this method.