Key Engineering Materials Vol. 591

Abstract: Sr₂CeO₄: Ho³⁺ was prepared by high-temperature solid-state method. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and photo luminescent (PL). The Sr₂CeO₄:Ho³⁺ phosphors showed a red emission under the near-ultraviolet excitation (280 nm) and the main emission centered at 475 nm. It has been found that A⁺ (A⁺ = Li⁺, Na⁺ or K⁺) codoped Sr₂CeO₄: Ho³⁺ phosphors could lead to a remarkable increase of photoluminescence. Luminous intensity was the highest when doping Li⁺ ions. Investigation indicated that Sr₂Ce_0.989O₄: 0.001Ho³⁺, 0.01Li⁺ exhibited the strongest emission. The average particle size was about 6 um. The optimum sintering temperature was 1200 °C and the possible mechanism was also discussed.

Abstract: Fifty-one yellowish-green color 5mm×7mm oval faceted peridots are experimented by Color i5 to test their color parameters, and concept of metamerism is introduced into this article, to analyze the effects of color parameters on the color appearance of peridots. SPSS analysis indicates: wavelength λ has no correlation with metamerism index MI, but excitation purity Pe has significant correlation with MI (rPe×MI=0.826, 0.01), means with the increase of excitation purity, the color appearance of peridot tend to be more unsteady and change more with the illumination conversion. Simultaneously, metamerism index MI increase with increasing chromaticity C* and lightness L* (rC*×MI=0.979, rL*×MI=0.889, 0.01), means the change of color appearance increase with illumination conversion. In conclusion, when the yellowish-green of peridot is more saturate and brighter, the effect of illumination on color appearance is greater.

Abstract: 48 yellowish green peridots examined to test the color parameter under the neutral backgrounds whose lightness values are 10, 20, 30, 40, 50, 60, 70 and 80 by Color i5 tester, combing with the color parameter of peridots themselves, such as lightness values L*∈(50,60), chroma values C*∈(27,45), make the influence of different backgrounds on peridots’color appearence clear.With the help of two-factor analysis method, get that the F index of Row factor(standing for the lightness of peridots themselves): 16.61 which is greater than the its Fcrit index:1.40, and the F index of Column factor(standing for the lightness of backgrounds): 193.99 which is much greater than the Fcrit index, either, thus it shows that the peridots’color appearance is not only resulted by their onw lightness, but also by the backgrounds’. What is more, the influence of backgrounds is more significant; and comparing all samples’ chroma index fit line under different backgroud, find out peridot’s chroma index turning to be greater when the backgrounds’lightness increasing, and the influences are obvious during the samples with high chroma indexes. It is concluded that, for the peridots with medium lightness,the neutral backgrounds impact more on their color appearence than their own lightness do, and with the increase of backgrounds’lightness, peridots’lightness and chroma indexes will be higher.

Abstract: Layered Molybdenum trioxide M_OO₃, with a two-dimensional (2D) structure was successfully delaminated into colloidal nanosheets in n-butanol via a soft-chemical process involving intercalation of dodecylamine. X-ray diffration (XRD) showd that: after intercalation spacing of the layered material expend to 2.69nm from 1.38nm, and Characterizations by transmission electron microscopy (TEM) and scan electron microscopy (TEM) confirmed the formation of unilamellar 2D nanosheet crystallites with an average lateral size of 400 nm. The obtained nanosheets exhibited photochromic properties upon UV-VIS excitation. The chromogenic nanosheet obtained in this study features the intense UV absorption and optically switchable Visible-to-IR absorption, which may be useful for window applications such as heat-absorbing films.

Abstract: Objective:To study the relative translucency of 5 veneered and glazed all-ceramic systems core material, including Procerra AllCeram Alumina, Vita In-Ceram Zirconium, Ivoclar Vivodent Empress, In-Ceram Spinell and Colored Zirconia. Methods: Under standard black and white background, the surface light reflectivity of 5 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 5 core materials all declined, and ranged from 0.6740 of In-Ceram Spinell to 1.00 of In-Ceram zirconia, among of that In-Ceram Spinell was most transparent. Conclusion: Among the groups, there is no significant differences among Empress II, Procera AllCeram and Colored Zirconia (IL1,IL2,IL3). Compared with Procera AllCeram and Vita In-Ceram Zirconium , Procera AllCeram has significant difference. There is a significant difference between Procera AllCeram and In-Ceram Spinell.

Abstract: The ZnO nanorods were prepared at 130 °C, 160 °C and 190 °C for 6 h by hydrothermal method. The structural and optical properties of ZnO nanorods were invesitigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). XRD pattern analysis showed that the ZnO nanorods are the hexagonal structure (space group P63 mc). No other crystal phases, such as Zn and Zn (OH)₂ were detected. FT-IR study identified the sharp peak that appeared at 573 cm^-1 is related with the ZnO stretching mode. Also, SEM images revealed that the diameter of a single ZnO crystal ranges from 100 to 300 nm and the length ranges from 1 to 3 μm.

Abstract: ZnS films have been deposited on glass substrates by chemical bath deposition (CBD). The optical and structural properties were analyzed by UV-VIS spectrophotometer and X-ray diffraction (XRD). The results showed that the prepared thin films from the solution using N₂H₄ as second complexing agent were thicker than those from the solution without adding N₂H₄ in; this is due to using second complexing agent of N₂H₄, the deposition mechanisms change which is conductive to heterogeneous deposition. When using N₂H₄ as second complexing agent, the crystallinity of ZnS thin films improved with a significant peak at 2θ=28.96°which can be assigned to the (111) reflection of the sphalerite structure. The transmittances of the prepared films from the solution adding N₂H₄ in as second complexing agent were over 85%, compared to those from the solution without N₂H₄ (over 95%). The band gaps of the ZnS films from the solution using N₂H₄ as second complexing agent were larger (about 4.0eV) than that from those from the solution without N₂H₄ (about 3.98eV), which indicated that the prepared ZnS films from the solution adding N₂H₄ in as second complexing agent were better used as buffer layer of solar cells with adequate optical properties. In short, using N₂H₄ as second complexing agent, can greatly improve the optical and structural properties of the ZnS thin films.

Abstract: Graphene material has ideal lattice structure and unique electrical, optical and other properties. In the electronics, composite materials, and other fields it has a broad application prospect. In this paper, using the Hummers method, to prepare oxidized graphite and graphene , to optimize the conditions of the preparation of graphite oxide. With two kinds of reductors, glucose and hydrazine hydrate, reduction graphite oxide, and dropped silver ions in the process of reduction. Using XRD, SEM and Raman spectra to character and analyze the products. The result showed that the graphite and silver ions in the oxidation reaction process were both restored by glucose, hydrazine hydrate. This structure that silver nanoparticles are uniformly distributed in the graphene sheet layers, can effectively prevent the reunion of graphene layers, and also upset the rules of the pile of the graphene layers.

Abstract: The color parameters of 19 pieces purity transparent and color uniform commercial grade tanzanites were measured by colorimeter Color i5 and this article introduces the concept of Metamerism and calculates the color quantitatively, based on CIE1976 L*a*b* uniform color space, analysis the contribution of different illuminators to the bluish-violet color of tanzanite. The change of hue-angle h0 is in contrast to the actual visual effect, this is called abnormal hue-angle change of the gemstone tanzanite; both of the contributions of lightness difference and chroma difference play the same role to the change of the color difference, form the bluish-violet of tanzanite; it is shown that Metamerism indexes (Mt) of different samples are different and the same sample’s main wavelength follows the change while illuminators altered. Therefore, while illuminators altered, the color of tanzanite samples change from blue to bluish-violet, and the Mt larger, the change of color is greater, namely, the violet hue is more clear, with the better color appearance.

Abstract: The existence of a temperature difference across a vacuum glazing causes dimensional differences between the hot and cold glass sheets, with associated mechanical stresses and bending. In order to understand the distribution characteristics of the stresses and deformation in vacuum glazing due to temperature difference, in this work, the mechanical models were established and the calculation formula of the shear stress in the edge seal and bending tensile stress on the surface of the two glass sheets of the vacuum glazing were given. A test device was designed and the maximum tensile stresses and deflection of the vacuum glazing with various temperature difference were tested by experimental, it was shown that they are identical between the experiments and the theories.