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31.
《Journal of the European Ceramic Society》2020,40(8):3270-3278
Ultra-stable CsPbBr3 perovskite quantum dots (QDs) multicomponent glass with high transmittance was prepared by melt-quenching heat treatment. The average diameter of the CsPbBr3 QDs was ∼1.96 nm. The resulting glass displayed a high exciton binding energy of 362 ± 18 meV. Notably, these glass-encapsulated materials exhibited excellent resistance to heat, light, and water, superior to that of previously reported perovskite-based materials, and underwent an extremely low rate of Pb leaching during water immersion. Based on the glass, a high-performance white light-emitting diode (WLED) device was fabricated with Commission Internationale de L’Eclairage (CIE) coordinates of (0.3156, 0.3326) and color gamut of ∼113 % National Television Standards Committee (NTSC). The CsPbBr3 QDs glass without rare earth elements further acted as an optical gain medium, realizing up-conversion lasing with 980-nm laser excitation for the first time. The reversible linear fluorescence response indicates that the glass could be a potential candidate for temperature sensors. 相似文献
32.
This work aims to investigate the unsteady conjugate interphase mass transfer between a stationary deformed drop and the modest extensional flow in a cross-intersected 2D channel. It is very difficult to accurately quantify the transient mass transfer rate of solute in such a geometry. Therefore, we established a mathematical model on the basic of the Stokes equation and solved it by the boundary element method, which could deal precisely with a two-phase flow system with a deformable interface; meanwhile, the convection-diffusion equation was solved by the finite difference method to calculate the unsteady conjugate interphase mass transfer. The simulation results showed that the mass transfer rate, analyzed and characterized in terms of mean concentration variation and Sherwood number Sh, was affected by capillary number Ca, Peclet number Pe, viscosity ratio λ , interior-to-exterior diffusivity ratio K, distribution coefficient m, and wall effect factor W. 相似文献
33.
34.
Haiyang Zhu Renli Fu Simeon Agathopoulos Jun Fang Guojun Li Qinjiang He 《Ceramics International》2018,44(9):10147-10153
The influence of BaO content (up to 15?mol%) on the crystallization behaviour, structure, thermal properties and microwave dielectric properties of the BaO-CaO-B2O3-SiO2 glasses and glass-ceramics system was investigated. The glasses were produced by melting at 1400?°C and quenching into water, and the glass-ceramics were produced via heat treatment at temperatures between 750 and 800?°C. The results of X-ray diffraction analysis showed that increasing the BaO content raised the resistance of the glass against crystallization and favoured the transformation of β-CaSiO3 and α-CaSiO3 phases, which crystallized in the Ba-free and in low BaO content compositions, into SiO2 and Ba4Si6O16, which crystallized in compositions with higher concentrations of BaO. The BaO content had little influence on the glass transition temperature (Tg) and the linear coefficient of thermal expansion (CTE), but strongly reduced the softening point (Ts). Even the addition of BaO as minor additives resulted in a dramatic reduction of the Ts; for example, the Ts decreased from 902?°C for the Ba-free composition to 682?°C for the BaO-containing one (5%). Low values of the dielectric constant (5.9?≤?εr ≤?6.63) and dielectric loss (1.12?×?10?3 ≤?tanδ?≤?3.15?×?10?3) were measured. 相似文献
35.
Enrico Kleebusch Christian Patzig Thomas Höche Christian Rüssel 《Ceramics International》2018,44(16):19818-19824
Glass-ceramics based on lithium-alumo-silicate glasses are commercially important for a wide range of applications, due to their special properties, like a vanishing thermal expansion. In order to tailor these properties, the composition of the glass and the temperature/time schedule are crucial factors. For the industrial production of most lithium-alumo-silicate glasses, high melting temperatures are required due to the high viscosities of the respective melt compositions. In this study, a simplified lithium-alumo-silicate glass composition with ZrO2 as nucleating agent, on the basis of the commercially available Robax® composition, is studied. Adding boron oxide leads to lower viscosities of the glass melt and notably lower melting temperatures may be supplied. The resulting glass is investigated using X-ray diffraction and transmission electron microscopy. During the crystallization process, phases such as ZrO2 and β-quartz types are formed. The microstructure of the glass ceramics is notably coarser than that of glass-ceramics which are obtained from lithium-alumo-silicate glasses of standard compositions. EDX-analyses indicate a considerable enrichment of chemical elements in comparatively small areas of the microstructure. Especially boron oxide is found to be enriched in the residual glass of the investigated glass-ceramics. 相似文献
36.
To explore the synergistic effect of glass fibre and Al powder on the mechanical properties of glass-ceramics, blast furnace slag was chosen as the main material, and glass fibre and Al powder as reinforcement materials. The phase compositions, microstructures, compressive properties, and apparent density of the glass-ceramics with varying quantities of glass fibre and Al powder were investigated. The experimental results indicated that Al powder could exist as a simple substance in glass-ceramics and form a dense net coating on the surface of blast furnace slag to improve the plasticity of the glass-ceramic. The glass fibre had better reinforcement effect than Al powder because of its extremely high mechanical strength. The plasticity of glass-ceramics, however, severely decreased; the glass-ceramics exhibited brittle failure during compression. A slight increase in the content of CaSi2 and SiO2 in the glass-ceramics was closely related to the addition of glass fibre. Considering safety and economy, glass-ceramics with 6% Al and 14% glass fibre (S4) have the best mechanical properties. The compressive strength, strain at maximum force, and apparent density were 40?MPa, 19% and 1.974?g/cm3, respectively. 相似文献
37.
Coproduction of Ethyl Acetate and n‐Butyl Acetate by Using a Reactive Dividing‐Wall Column 下载免费PDF全文
The performance of the reactive distillation dividing‐wall column for coproduction of ethyl acetate and butyl acetate was experimentally studied. n‐Butanol and ethanol are raw reaction materials that react with acetic acid in the reaction zone to produce n‐butyl acetate and ethyl acetate, respectively. n‐Butyl acetate is not only a product, but also acts to remove water generated by the esterification reactions. The effects of various parameters, such as catalyst loading per stage, reflux ratio, liquid split and molar feed ratios, ethyl acetate/n‐butyl acetate purity, pressure drop, and total energy consumption, are investigated. Results show that ethanol could be completely converted and the products could be easily separated, which shows great industrial application potential in the coproduction of ethyl acetate and n‐butyl acetate. 相似文献
38.
Dynamic Performance of a Complex Distillation System to Separate a Five‐Component Hydrocarbon Mixture 下载免费PDF全文
Juan Gabriel Segovia Hernández Fernando Israel Gómez-Castro Eduardo Sánchez-Ramírez 《化学工程与技术》2018,41(10):2053-2065
Distillation is one of the most used separation processes in chemical industry, although it is a highly energy‐intensive operation. For multicomponent distillation, complex structures have been proposed in previous works, which may allow energy savings. Nevertheless, it is mandatory to understand the dynamic characteristics of such complex structures. In this work, the dynamic performance of a dividing‐wall‐based structure for the separation of a five‐component mixture is studied. A sensitivity analysis is performed on the structure in terms of the interlinking streams, performing a singular value decomposition analysis to selected cases with different operational conditions. The designs with the lowest energy duties also showed the best open‐loop properties. 相似文献
39.
Hierarchical micro-nanostructured albite-based glass-ceramic for high dielectric strength insulators
V. Fuertes M.J. Cabrera J. Seores D. Muñoz J.F. Fernández E. Enríquez 《Journal of the European Ceramic Society》2018,38(7):2759-2766
A novel glass-ceramic material based on albite type Na-rich feldspar has been synthesized by conventional ceramic process. High crystallinity, >94%?Vol.% is obtained by fast sintering which allows energy saving processing. Albite is the main crystalline phase and tetragonal SiO2 is a secondary phase. Electrical properties were examined by complex impedance, DC measurements, and dielectric breakdown test. Dielectric characterization shows a non-Debye type dielectric behavior with low dielectric constant, 4.6 at 1?MHz, low dielectric losses, (~10?3 at 1?MHz, and a large dielectric strength, ~60?kV/mm), that it is the largest value reported in ceramic insulators. Those dielectric properties are attained by the low glassy phase content in the samples and their unique micro-nanostructure. All these properties make this novel material a very promising candidate in the market of ceramic electrical insulator, highlighting for high-voltage applications. 相似文献
40.
《Ceramics International》2020,46(1):186-195
The Al2O3/SiO2–B2O3–Al2O3–Na2O glass/Al2O3 joints reinforced cooperatively by glass matrix and in-situ Al4B2O9 whiskers were obtained via a low-melting borosilicate glass braze. The composition of glass seam transformed from SiO2–B2O3–Na2O to SiO2–B2O3–Al2O3–Na2O due to continuous diffusion and dissolution of Al2O3. An appropriate amount of [AlO4] units introduced into the glass braze played a vital role in strengthening the glass network structure resulting to considerably improved mechanical strength of the glass seam. Meanwhile, plenty of in-situ Al4B2O9 whiskers growing from the Al2O3/glass braze interface to the center of glass seam in various directions generated. Three-dimensional crisscross structures were fabricated at the Al2O3/glass braze interface domains, where were enhanced by crack-bridging and pull-out effect of the whiskers. Generally, ascribed to the cooperative reinforcement of the glass matrix in the seam and in-situ Al4B2O9 whiskers at Al2O3/glass braze interface domains through reactions of Al2O3 and borosilicate glass braze, strength of the as-brazed joints was promoted prominently. The shear strength of the joints reached a maximum of 61 MPa brazed at 1050 °C for 60 min. 相似文献