Key Engineering Materials Vols. 512-515

Abstract: Compared to phosphors, scintillating films are shown as a better feature for high–resolution display devices with low loss diffusion. Ce ³⁺ doped lutetium aluminum garnet (Lu₃Al₅O₁₂, LuAG) scintillating films with different Ce ³⁺ concentration have been fabricated by Pechini sol–gel processing combined with the spin–coating technique and characterized by X–ray diffraction (XRD) and photoluminescence (PL) under excitation of UV–VIS light. The results of XRD patterns indicated that the specimen under study is a well–crystallized single–phase of cubic structure. Under an excitation of 442nm , it was found that the PL spectra was the typical Ce ³⁺ emissions located in the 460–650 nm consisting of two emission bands due to the transitions from the lowest 5d excited state (2D) to the 4f ground state of Ce ³⁺ , which matches well with the sensitivity curve of the Si–photodiode . The luminescent intensity of LuAG: Ce ³⁺ films varies with the Ce ³⁺ contents and reaches the maximum at 1.0 mol% doped. With the increase of calcining temperature, the luminescence intensity in the PL spectra of LuAG:Ce ³⁺ films was found to increased accordingly due to the improved crystallization.

Abstract: In this experimental, solid state method is used to synthesize proportioned nano-ZnO and SiO₂ powders into Zn₂SiO₄ phosphor, and to achieve better control on grain size and grain shape than traditional powder. La is used to replace Mn; and to achieve better control on grain size and grain shape than traditional powder. With different sintering conditions, With different sintering conditions, the effect of the luminescent intensity due to sintering temperature and the concentration of activator would be discussed by the X-Ray Diffraction, SEM and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles. Photoluminescence (PL) spectroscopy was utilized to characterize the optical properties. This use of phosphor materials is the application of the main light source, display components. Therefore, our study zinc silicate as the main principle of doping Mn, La of the characteristics of, expects to find the best glow.

Abstract: Fe-Co-Ni-Cr spinels have been prepared by conventional solid state sintering. The valence states and distribution of transition ions are be studied by the XPS analysis,thermodynamics analysis and crystalline field theory.The crystal structure and infrared radiant properties are studied by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), IR radiation tester and band theory.With the change of Fe/Cr, the states of occupying are also change,leading to the information of different products of different lattice parameters and the variation of the spin state of Fe³⁺ in octahedral sites，which causing the change of infrared radiation properities, and the action of different spin states of Fe³⁺ and carriers has an important influence on infrared radiant properties in the 3～5μm band with increasing of the content of Fe.The optimized sample s3 exhibits the average emissitivity is 0.915 in the whole band,0.833 in the 3～5μm band and 0.948 in the 8～14μm band,respectively.

Abstract: Fe–Mn–O Ceramics Have Been Synthesized by Conventional Solid State Reaction. the Structure and Infrared Radiation Properties of (1+x)Fe₂O₃•MnO₂ Compounds Were Studied by X-ray Diffraction(XRD) and IR Radiation Tester. X–ray Photoelectron Spectroscopy(XPS) Analysis Shows the Valence States. the Phases of All Samples Change from Complex Oxides to Spinel–like Structure with the Increasing of X.And Fe and Mn Element of All Samples Also Have Two Different Valence States Exsistence.According to the Measurement Results of Sheet Resistance and the Radiation Tester Analysis, the Sheet Resistance and Infrared Radiance Have Shown a Corresponding Variation, and the Infrared Radiation Properties in the 3˜5µm Waveband Are Influenced by the Carrier Transport and the Distortion of the Crystal Structure.the Sample with X=0.4 Exhibits the Average Emissitivity Is 0.94 in the 3˜5μm Waveband at Room Temperature,and the Result Shows that Fe–MnO Compounds Can Application in Energy–saving of High Temperature in Industrial Furnace.

Abstract: In this paper, ZnO nanopowders and dye sensitized solar cells were prepared by sol-gel and screen printing method, respectively. First, ZnO nanopowders were synthesized by using zinc acetate, ethanol and diethanolamined as raw materials. The effects of Zn2+ molar concentration on the microstructure and photocatalytic efficiency of ZnO nanopowders were investigated. When Zn2+molar concentration were 0.4M, 0.6M, 0.8M and 1.2M, ZnO nanoparticles with diameter of about 80~100nm were obtained. When Zn2+ molar concentration reached 2.4M, ZnO nanobowls consisted of nanoparticles with diameter about 80~100nm were synthesized. When Zn2+molar concentration reached 3.6M, ZnO nanoparticles were obtained, and particle size distribution of obtained ZnO nanoparticles became broader. Methyl orange degradation rate of ZnO nanopowders prepared with 0.4M, after treated by ultraviolet radiation for 8 hours, were up to 88.5%. ZnO nanopowders prepared with 1.2M and 3.6M were assembled into solar cells. The properties of the solar cell prepared with 1.2M were optimal. The short-circuit photocurrent, open-circuit photovoltage, fill factor and efficiency were 14.72 mA/cm2, 0.649V, 0.332 and 0.914%, respectively.

Abstract: Lead lanthanum zirconate titanate (PLZT) transparent ceramics present an attractive electrically controlled light scattering performance with high transmittance and large contrast ratio. PLZT ceramics of 8 mole% lanthanum with different Zr/Ti ratios (Zr/Ti=68/32, 70/30, 72/28) were prepared by the hot pressing method to figure out the influence of Zr/Ti ratios to the light scattering performance. X-ray diffraction patterns confirm that all the samples are perovskite structure with no secondary impurity phase detected. All the three compositions show double tending slim hysteresis loops which due to antiferroelectric phase coexisted. Besides, within the range of near-infrared to ultraviolet wavelength, all the PLZT samples show high transmittance. While the Zr/Ti ratio increasing from 68/32 to 72/28, the transmittance reduced value R_T of the sample decreases gradually (λ: 632.8 nm). PLZT (8/68/32) sample shows a maximum R_T, it promises a good application in optical modulators, goggles and so on.

Abstract: Abstract. The Si and SiC in wire cutting waste slurry from photovoltaic silicon were recovery and separation by froth floatation in this paper, and the lauryl amine and sodium hamates were used as collector and flocculants, respectively. The effects of collector concentration, inhibitor species, and solution temperature and pH value on separation efficiency were investigated. The morphology of collected solid was characterized by SEM.The phase composition of collected solid was characterized by XRD. Laser particle seizer was used to study the particle size distribution. The results showed that temperature had little effect on the flotation efficiency. When pH value was 7, the lauryl amine adapts to neutral environment and the collecting effect of collector was the best, and cellulose was considered to be the best inhibitors in four different inhibitors. When volume fraction of lauryl amine, sodium humate flocculant, cellulose inhibitor, and temperature and pH value were 0.16%, 0.16%, 0.25‰, 30°C and 7, respectively, the solid collecting rate and collected SiC purity were respectively 51.94% and 94.7%.

Abstract: In this paper, pure ZnO nanospheres and IO3- ions doped ZnO nanospheres were prepared by heating under reflux with zinc acetate and diethylene glycol as raw materials, and the ZnO dye-sensitized solar cells (DSCs) were prepared. The influences of reaction time and IO3--ions dope on ZnO properties were studied. DSCs properties prepared with obtained ZnO nanospheres were investied. ZnO nanospheres were characterized by XRD, SEM and infrared absorption spectrogram. The results showed that when the temperature was 160°C, ZnO nanospheres with diameter 100-800nm were obtained. When reaction time was 2h, ZnO diameter was about 500nm. When the reaction time was 24h, the diameter of ZnO was about 800nm with wider distribution. The ZnO DSCs were prepared by using ZnO nanopowders with different reaction time as photoanode. The photoelectric conversion efficiency of 24h-ZnO DSCs was the highest. The photoelectric conversion efficiency, open circuit voltage, short-circuit current and fill factor were 2.15%, 0.64V, 6.47 mA•cm-2, 0.52, respectively.

Abstract: Abradable coatings are used in gas turbines to reduce the clearance between rotating and stationary parts, thereby improve the efficiency and reduce the oil consumption. Besides, the abradable coatings also have to prevent the alloy blade from wearing out. Common used abradable coatings have a diphase structure with hard, strong matrix and soft, self-lubricant phase. In this work, yttria-stabilized-zirconia was used as matrix, and layer-structured LaPO₄ or Ti₃SiC₂ was lubricant phase. The samples were prepared by both pressureless sintering and SPS. The regularity of the mechanical properties, such as hardness and modulus, influenced by the lubricant content were studied. And the abradability was also measured by SRV high temperature friction tester.

Abstract: Use starch, corn meal and activated carbon as pore-making agent, Ni-YSZ/YSZ composite ceramic green body was prepared by multiple gel-tape casting with acryloyl ammonium-polyvinyl alcohol. The specimen was sintered at 1450°C for 4h, then reduced in hydrogen atmosphere at 800°C for 4h, Ni-YSZ/YSZ composite ceramic disk was obtained, the porosity, thermal expansion coefficient, electrical properties and microstructures of the specimen was tested. The results showed that the porosity of Ni-YSZ/YSZ composite ceramic disk reaches about 30% when use starch as pore-making agent, expansion coefficient is proportional to porosity, both of them reduced with the temperature increased. The YSZ is continued and compact with network structure, Ni particulates are well distributed in it, suitable for intermediate temperature solid oxide fuel cell anode materials. Image analysis of SEM micrograph showed that the structure is loose, porous, uniform and compact in Ni/YSZ/YSZ multi-layer composite ceramics, which meet the requirement of intermediate temperature SOFC.