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1.
Sm3+-doped SrO–Al2O3–SiO2 glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-ceramics were investigated. The results indicate that the crystal phase in this system is monocelsian (SrAl2Si2O8). Under the excitation with blue light (475 nm) the Sm3+-doped SrO–Al2O3–SiO2 glass-ceramics emit green, orange and red lights centered at 565, 605, 650 and 715 nm, which can be assigned to the 4G5/2 → 6HJ/2 (J = 5, 7, 9, 11) electron transitions in Sm3+ ions, respectively. With the increase of nucleation/crystallization temperature, the crystallite part rises from 66 to 79%. Besides, by increasing crystallization temperature or concentration of Sm3+, the samples emission located at 565, 605 and 650 nm is intensified significantly. We envision that, by fine controlling and combining of these three (green, orange and red) lights in an appropriate proportion, the Sm3+-doped glass-ceramics are promising luminescence materials for white light-emitting diodes devices. 相似文献
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S. V. Mulevanov V. M. Nartsev A. N. Trofimov O. F. Beinarovich I. N. Gavrikova 《Glass Physics and Chemistry》2017,43(2):188-190
It is shown that the phase heterogeneity of SiO2–Na2O–Al2O3 glass has a liquation and crystallization nature, the balance between which is determined by the conditions of their synthesis. An increase in the aluminum oxide content decreases the number of liquation and crystallization sites, and also the linear sizes of the crystalline formations without eliminating the phase separation due to the liquation. The area of metastable immiscibility in the SiO2–Na2O–Al2O3 system, which is determined by scanning electron microscopy, is probably wider than the area detected by the optical methods. 相似文献
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Vapor–liquid equilibria of binary components of the BrCF2COOCH3–CF3COOH–BrCF2COOH–CF3COOCH3 quaternary system have been studied experimentally at constant pressure. The experiments have been carried out on a modified Sventoslavskii ebulliometer. Using the Aspen Plus software package, the appropriate models have been selected and the vapor–liquid equilibria for six binary systems have been simulated. 相似文献
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The concentration and the type of Cu2+ species adsorbed on a natural zeolite (Clinoptilolite) was measured and studied by using Electron Paramagnetic Resonance
Spectroscopy (EPR). The EPR results together with macroscopic sorption data indicate that the solution ionic strength as well
as, the type of electrolyte anion (Cl−, NO3− and SO42− ions were examined) affect the amount of Cu adsorbed and the type of Cu surface complexes. The increasing in solution pH
affects Cu adsorption quantitatively whereas; the type of surface complexes formed depends mainly on solution ionic strength.
For low solution ionic strength, when the inhibition from solution species is limited, the adsorbed Cu is characterized by
more than one type of chemical environment. On the contrary, for high solution ionic strength the Cu adsorption is inhomogeneous
and EPR spectra show only one type of surface complex. When the anions of the background electrolytes are different, but of
equal normality, the results indicate that in the presence of SO42− discernible Cu surface complexes are formed whereas, for Cl− and NO3− these surface formations are obtained only for high Cu adsorbed concentrations. 相似文献
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Some photon interaction parameters such as mass attenuation coefficient, effective atomic number, half value layer, mean free path and electron density for 15ZnO–(17.5–x)Al2O3–xFe2O3–67.5P2O5 glass system (x = 0, 7.5, 12.5, 17.5) and 15ZnO–(25–x)Al2O3–xFe2O3–60P2O5 glass system (x = 0, 25) have been investigated in the photon energy range of 1 keV to 100 GeV. It has been observed that all the photon interaction parameters for the selected glass systems vary with the photon energy. Among the selected glass systems, the sample 15ZnO–25Fe2O3–60P2O5 glass system shows maximum values for mass attenuation coefficients, effective atomic numbers, electron densities and minimum values for mean free path and half value layer in the entire energy grid. 相似文献
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Idris Kabalci Erkan Koc Sirri Semih Ozturk 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(3):788-794
Oxide based optical glass materials has important potential material in many applications from fiber optic to sensor due to the high transparency and amourphous structures. The objective of this study is to synthesize the novel optical glass materials based on the bismuth and aluminum contents to be able to determine the physical, chemical and mechanical properties by considering the systematic experimental steps. In this study, Bi2O3–Al2O3 based tellurite optical glasses have been prepared by using conventional melt quenching method as a function of the both Bi2O3 and Al2O3 compositions. There is a strong interactions between the glass former and modifier ions that might effect on the structure and mechanical properties. During the experimental steps, thermal, structural and mechanical properties of the prepared glass materials have been determined considering the DTA/DSC, FT-IR spectroscopy, SEM and Vicker’s hardness techniques, respectively. Thermal parameters, like glass transition, Tg, onset, Tx, crystallization, Tp, and melting, Tm, temperatures were obtained by using DTA scan. 相似文献
8.
Pawel Mierczynski Radoslaw Ciesielski Adam Kedziora Waldemar Maniukiewicz Tomasz P. Maniecki 《Catalysis in Industry》2017,9(2):99-103
Monometallic copper and bimetallic palladium-copper catalysts supported on ZnO–Al2O3 and ZrO2–Al2O3 were prepared by conventional impregnation method and tested in methanol synthesis reaction under elevated pressure (3.5 MPa) in gradientless reactor at 220°C. The physicochemical properties of prepared catalytic systems were studied using BET, X-ray, TPR-H2, TPD-NH3 techniques. The promotion effect of palladium on catalytic activity and selectivity of copper supported catalyst in methanol synthesis reaction was proven. The highest activity of this system is explained by the Pd–Cu alloy formation. 相似文献
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E. A. Buluchevskii E. D. Fedorova A. V. Lavrenov M. V. Zhuravleva 《Catalysis in Industry》2018,10(2):118-125
The effect of the hydroisomerization conditions of the benzene-containing fraction of catalytic reforming gasoline on the yield and composition of products is studied on Pt/B2O3–Al2O3 and Pt/WO3–Al2O3 catalysts. These catalysts allow benzene to be completely removed from the raw material. At the same time, the greatest yields of liquid products are obtained with minimal losses of the octane number at 2 MPa, a mass feedstock hourly space velocity (MFHSV) of 2 h?1, and 325°C: 96.3 and 95.4 wt % on Pt/B2O3–Al2O3 and Pt/WO3–Al2O3 catalysts, respectively. The activity of the catalysts is maintained for 100 h during their operation. 相似文献
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A. O. Chauhan A. B. Gawande S. K. Omanwar 《Journal of Inorganic and Organometallic Polymers and Materials》2016,26(5):1023-1027
The phosphors LiSrPO4:Gd3+ and LiSrPO4:Gd3+, Pb2+ with different concentration of Gd3+ and Pb2+ were synthesized by combination of re-crystallization and modified solid state diffusion method. The synthesized phosphors were characterized using XRD, SEM and PL spectroscopies. The PL excitation spectra of LiSrPO4:Gd3+ phosphor exhibit peak at 275 nm due to the 8S7/2 →4IJ transition of Gd3+ ions and gave narrow UVB emission at 312 nm. The effect of Pb2+ ions on the PL properties of LiSrPO4:Gd3+have also been investigated. Upon the addition of Pb2+ ions, the excitation of phosphors shows broad peak with maximum at 247 nm, overlapping the Hg 253.7 nm line. This addition of Pb2+ ions improved the emission intensity of narrow band UVB i.e. 312 nm under the excitation of 247 nm. The phosphor could be good candidate as phototherapy lamp phosphor material. 相似文献
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S. S. Ordan’yan S. V. Vikhman Yu. S. Nagaeva 《Refractories and Industrial Ceramics》2009,50(2):127-130
Sections are constructed for WSi2–Me
VB2 of the quaternary systems W–Si–(V, Nb, Ta)–B described by eutectic diagrams of state with T
eut (1940 ± 20), (1980 ± 20) and (2020 ± 30)°C and a boride content in the eutectics of 35, 20 and 15 mol.% respectively.
Translated from Novye Ogneupory, No. 3, pp. 41 – 44, March 2009. 相似文献
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Nichola J. Coleman Samantha P. Lewis Andrew P. Mendham Vivek Trivedi 《Journal of Porous Materials》2010,17(6):747-753
Zirconium umbite, K2ZrSi3O9·H2O, is a microporous framework ion exchanger whose potential as a carrier for Zn2+ ions in antimicrobial formulations has not yet been investigated. Accordingly, batch Zn2+-exchange kinetics of synthetic zirconium umbite (K-UM) and the subsequent antimicrobial action of the zinc-bearing phase
(Zn-UM) against Staphylococcus aureus and Escherichia coli are reported. Nonstoicheiometric over-exchange of Zn2+ for K+ was observed and attributed to hydrolysis and complexation reactions of Zn2+ within the umbite framework. The exchange process, which was described by a simple pseudo-first-order model (k
1 = 2.69 × 10−4 min−1, R
2 = 0.992), did not achieve equilibrium within 120 h at 25 °C, by which time the uptake of zinc was found to be 1.04 mmol g−1. The minimal bactericidal concentrations of Zn-UM for E. coli and S. aureus were found to be >10 g cm3 and <1.0 g cm3, respectively. 相似文献
14.
Lianwei Shan Jun Ding Wenli Sun Zhidong Han Liguo Jin 《Journal of Inorganic and Organometallic Polymers and Materials》2017,27(6):1750-1759
To enhance the photocatalytic activity of monoclinic scheelite (ms) BiVO4 for dye degradation, the heterostructured core (BiVO4)/shell (BiVO4:Eu3+) samples were synthesized by sol–gel method. The samples were characterized by UV–Vis diffuse reflectance spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). The results reveal that as-synthesized photocatalysts are characteristic of ms core/shell structure, responsive to visible light. The XPS spectra confirm that the doped Eu3+ mainly distributed in the outside layer of BiVO4 particle. The valence band (VB) spectra indicate the shell (BiVO4:Eu3+) exhibits a high carrier mobility. The core/shell photocatalysts showed higher photocatalytic activity than pure BiVO4 through degrading Rhodamine B and Methylene blue. The better performance of core/shell heterojunction mainly results from that the Eu3+ ions selectively present on shell layer, increasing the VB value of shell layer (forming a interface electric field with core) and carrier mobility. It is considered that the half-filled 7f–electron configuration of Eu3+ can improve the electron trapping and transfer. Besides, the low PL intensity and high SBET of BiVO4/BiVO4:Eu3+ contribute to enhanced photocatalytic performances. 相似文献
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A highly dispersive powder with a (ZrO2)0.92(Y2O3)0.03(Gd2O3)0.03(MgO)0.02 composition and specific surface area of 150 m2/g has been synthesized via a method of coprecipitation of hydroxides with the subsequent cryochemical treatment of the gel. Nanoceramics based on the cubic modification of zirconium dioxide with the grain size of ~40–45 nm have been obtained. The temperature dependence of the specific electrical conductance of the nanoceramics within a temperature range of 350–870°C in air has been studied, and the ratio of the ionic and electronic parts of the conductance has been determined. Recommendations for the use of the obtained oxide nanocomposite as an electrolyte for a high-temperature fuel cell have been given. 相似文献
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Vitrification in the Ga2S3–GeS2–PbF2 system is considered. The physicochemical properties of glasses, such as density, microhardness, electroconductivity, refraction index, and transmission percentage of specimens in visible and IR ranges of spectrum are studied; differential thermal analysis is carried out; and Raman and electron paramagnetic resonance spectra are investigated. 相似文献
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The results of the studies of the conditions of the liquid-phase synthesis of highly dispersed xerogels with a low degree of agglomeration and precursor nanopowders (~10–12 nm) based on zirconium dioxide in the ZrO2–HfO2–Y2O3(CeO2) system are presented. The thermal decomposition of xerogels and formation of crystalline solid solutions with the structure of fluorite are investigated. The optimal conditions for the solidification of nanodispersed powders for fabricating compact ceramics based on solid solutions of ZrO2 and the physical–chemical properties of these ceramics are studied. 相似文献
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L. V. Morozova M. V. Kalinina T. V. Khamova E. A. Vasil’eva O. A. Shilova 《Glass Physics and Chemistry》2016,42(4):408-413
The results of the studies of the process of fabricating ceramic filtration membranes in the system ZrO2(Y2O3)–Al2O3 are presented. The phase compositions of the precursor powders and sintered ceramics have been investigated and their porous structures have been determined. Two stages of the implementation of the technology were demonstrated: fabrication of substrates with an open porosity ranging from 20 to 47% and pore sizes in the 100–300 nm range, as well as the deposition of nanocrystalline aluminum oxide layers on them. It has been established that the pore size distribution in the membrane layer of α-Al2O3 is unimodal (from 30 to 100 nm). 相似文献
19.
Yoshio Takasu Wataru Sugimoto Yoshinori Nishiki Shuji Nakamatsu 《Journal of Applied Electrochemistry》2010,40(10):1789-1795
The morphology and composition of RuO2–TiO2/Ti and IrO2–RuO2–TiO2/Ti anodes, which have been used for the production of chlorine for more than 10 years, were analyzed by various methods;
such as high-resolution scanning electron microscopy, high-resolution Auger electron spectroscopy, electron probe X-ray emission
microanalysis and X-ray diffraction analysis. Drastic changes in the surface morphology, including partial exfoliation of
a small amount of the oxide layer and a reduction in the content of ruthenium species through dissolution, were observed for
the RuO2–TiO2/Ti anode. For the IrO2–RuO2–TiO2/Ti anode, on the other hand, there were moderate changes in the surface morphology and moderate dissolution of iridium and
ruthenium species. 相似文献