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本文采用光电子能谱分析方法,首次研究Li_2S-SiS_2-LiBO_2-LiCl体系硫氧化物玻璃锂离子导体的组成、结构和状态。指出在该玻璃体系中,除与硅(硼)相键合的桥硫存在外,还有不与硅(硼)相键合的非桥硫存在;玻璃中的硫取代了氧的位置,进入玻璃网络中使结构紧密交联。对网络中的元素状态,成键及性能进行了讨论。 相似文献
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An Intermediate-temperature H2S Fuel Cell with a Li2SO4-based Proton-conducting Membrane 总被引:3,自引:0,他引:3
A laboratory-scale intermediate-temperature H2S fuel cell with a configuration of H2S, (metal sulfide-based composite anode)/Li2SO4+Al2O3/(NiO-based composite cathode), air was developed and studied for production of power and for desulfurization of a fuel gas process stream. The cell was run at typical temperature (600-650℃) and ambient pressure, but its electrochemical performance may be limited by electrolyte membrane thickness. The membrane and its performance in cell have been characterized using scanning electron microscope (SEM) and electrochemical impedance spectrum (EIS) techniques. Composite anodes based on metal sulfides, Ag powder and electrolyte behaved well and stably in H2S stream, and composite cathodes based mainly on nickel oxide, Ag powder and electrolyte had superior performance to Pt catalyst. The maximum power density of up to 70mW.cm^-2 and current density of as high as 250mA.cm^-2 were obtained at 650℃. However, the long-term cell stability remains to be investigated. 相似文献
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The possibility of using vanadium pentoxide (V2O5) as a catalyst in rechargeable lithium–oxygen (Li–O2) batteries was studied. A V2O5-carbon composite was cast onto Ni foam to form a cathode. Electrochemical cells designed based on the flat cell manufactured by Hohsen Corporation were fabricated. The initial discharge capacity was 715 mA?h?g?1, and the maximum discharge capacity reached 2,260 mA?h?g?1 during the twelfth cycle. The cell had high capacity retention during cycling (1.24?% during cycles 2–8). V2O5 acted as a catalyst as well as an active material, improving the specific capacity and capacity retention of the non-aqueous Li–O2 cell more effectively than do other materials. 相似文献
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Pavel P. Fedorov Vera Y. Proydakova Sergey V. Kuznetsov Valery V. Voronov Alexandr A. Pynenkov Konstantin N. Nishchev 《Journal of the American Ceramic Society》2020,103(5):3390-3400
The thermal analysis and X-ray powder diffraction studies of the Li2SO4–Na2SO4 system, including the high-temperature X-ray diffraction technique, have elucidated four phases of variable composition: three solid solutions based on the α-Li2SO4, α-Na2SO4, and α-LiNaSO4 high-temperature polymorphs, and a low-temperature β-LiNaSO4 phase. α-Na2SO4-Base solid solution disintegrates into two phases via a monotectoid phase transformation. It is quite probable that the monotectoid process is related to the conversion of the second-order phase transition to the first-order phase transition. 相似文献
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《Fuel Processing Technology》1988,19(2):141-152
A novel experimental system was adapted to determine factors controlling selective absorption of hydrogen sulfide (H2S) from carbon dioxide (CO2). This work demonstrates that liquid film controlled mass transfer regime and a low value of the liquid side mass transfer coefficient favors selective removal of H2S from CO2. By identifying the factor controlling selective removal of H2S from CO2, this work lays the basis for the parameter optimization of a process for selective removal of H2S from CO2. 相似文献
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《Ceramics International》2017,43(13):9769-9777
Glass ceramics based on the system Li2O/Al2O3/SiO2 (LAS) often show a coefficient of thermal expansion close to zero. Although these glass-ceramics are of high economic importance, the fundamentals of the crystallization process are still not fully understood. In this paper, the effect of ZrO2 addition as a sole nucleation agent on the crystallization of the LAS glass is described predominantly using transmission electron microscopy and X-ray diffraction. The composition of the studied green glass was close to that of the commercially available Robax™ glass (Schott AG), which, however, contained both, ZrO2 and TiO2 as nucleating agents. It was found that during thermal treatment, in a first step, already at temperatures around 10–20 K below the glass transition temperature, Tg, ZrO2 nanocrystals with sizes in the range from 5 to 15 nm were precipitated. The next crystalline phase that forms during the crystallization process was LAS with a structure similar to the hexagonal high temperature phase of quartz. These crystals were much larger than the ZrO2 crystals. If thermal treatment was carried out at higher temperatures, a dense network of LAS crystals was formed. Differently shaped crystals in samples with different thermal history were visualized, and an enrichment of Ba and Sb in the residual glass phase in the late stages of thermal treatment was found. Also, an enrichment of aluminum around the ZrO2 crystals was evident, which is a hint at a preceding droplet phase separation from which the ZrO2 crystals were precipitated. The crystallization is notably different from that of mixed ZrO2/TiO2 nucleating agents used in commercial lithium alumosilicate glass ceramics. 相似文献
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《Ceramics International》2016,42(7):8395-8401
The study of thermoelectric transport properties in Cu2−xSe and Cu2S has gained an importance in the thermoelectric research during last few years due to their superionic behavior and low cost. Here, we reported a facile method to enhance the thermoelectric efficiency of Cu2−xSe by introducing Cu2S nanoparticles (NPs) in the matrix of Cu2−xSe. The observed efficiency is a direct result of simultaneous improvement of Seebeck coefficient (S) because of the external strain induced by Cu2S nanoinclusions in Cu2−xSe and decline in the total thermal conductivity by suppressing both electronic and lattice thermal contributions. Such higher S and lower thermal conductivity is realized for a composite structure with 10 wt% nanoinclusions of Cu2S which effectively contributed to higher ZT value of 0.90 at moderate temperature of 773 K. Thus, it is believed that the proposed hybrid structure is a promising p-type thermoelectric material for mid-temperature range energy harvesting applications. 相似文献
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U.B. Shinde Sagar E. Shirsath S.M. Patange S.P. Jadhav K.M. Jadhav V.L. Patil 《Ceramics International》2013,39(5):5227-5234
Stoichiometric compositions of ferrites with the chemical formula Li0.5?0.5xCoxFe2.4?0.5xDy0.1O4 with x=0, 0.25, 0.5, 0.75, 1.0 were prepared by the standard double sintering ceramic method. X-ray diffraction analysis confirmed the cubic spinel structure of the prepared samples. The structural, morphological and magnetic properties were studied by X-ray diffraction, infra-red spectroscopy (IR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and ac susceptibility measurements. Lattice constant, grain size and density increase whereas porosity decreases with the increase in Co2+ substitution. IR measurements show the characteristic ferrite bands. Spectral absorption bands were observed in IR spectroscopic analysis at ν1=564?601 cm?1, ν2=486?519 cm?1 and ν3=551?578 cm?1. The cation distribution estimated by the X-ray diffraction is supported by magnetization and susceptibility studies. The saturation magnetization decreases from 44.25 to 17.14 emu/g whereas coercivity remarkably increases from 240.69 to 812.14 emu/g with increasing Co2+ substitution. The mechanisms involved are discussed. 相似文献
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《Cement and Concrete Research》1987,17(4):532-538
The lifetime spectrum of positron in β-C2S of added Na2O or P2O5 is studied with positron annihilation technique. According to the theory of the capture of positron, we discuss the relationship between lifetime spectrum parameters obtained through experiment and the microstructure of β-C2S. The results show that the long living component τ2 (about 470 ps) represents the capture of positron in the defects of Ca2+ vacancies and that the intensity of I2 of τ2 decreases with the increasing of Na+ and increases with the increasing of P5+. The results also verify that Na+ replaces Ca2+ and creates anion vacancies; while P5+ replaces Si4+ and creates cation vacancies. Vacancy concetration increases Na+ and P5+. Our work shows that the positron annihilation technique is a useful tool for studying the change of microstructure defects in doped β-C2S. The relationship between heat treatment and hydration activity of doped β-C2S and its impurities are also studied and discussed. 相似文献
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《Ceramics International》2016,42(5):6005-6009
Li2MnO3 ceramics co-doped with 2 wt% LiF and x wt% TiO2 (x=0, 3, 5, 7, 10) were prepared by solid-state reaction for low-temperature co-fired ceramics (LTCC) applications. The sintering temperatures of Li2MnO3 ceramics were successfully lowered to 925°C due to the formation of a LiF liquid phase. Their temperature stability was improved by doping with TiO2. A typical Li2MnO3-2 wt% LiF-5 wt% TiO2 sample with well-densified microstructures displayed optimum dielectric properties (εr=13.8, Q×f= 23,270 GHz, τf=1.2 ppm/°C). Such sample was compatible with Ag electrodes, which suggests suitability of the developed material for LTCC applications in wireless communication systems. 相似文献
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《Journal of the European Ceramic Society》2003,23(3):527-536
The formation of lithium ferrites (LiFe5O8 and LiFeO2) from mechanically activated mixtures of Li2CO3–Fe2O3 has been studied using thermal analysis (TGA, DSC), evolved gas analysis (TG/FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and particle size analysis. It is shown that mechanical activation of the precursors considerably enhances the reactivity of the solid system analysed and makes it possible to obtain reaction products with a much lower expense of thermal energy. In particular, lithium ferrites can be obtained at temperatures at least 160 °C lower than those necessary in the absence of mechanical activation. Moreover, both the microstructure and the allotropic ratio of the products, as well as the reaction path, are affected by mechanical activation. 相似文献
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Linling Tan John C. Mauro Jie Peng Xinlei Yang Mingying Peng 《Journal of the American Ceramic Society》2019,102(1):185-194
Tantalum silicate glasses serve as laser host materials to take advantage of their high refractive index and the ability to tailor their physical properties in the design of high-performance photonic and photoelectric components. However, successful attainment of feature control in tantalum-doped materials remains a longstanding problem due to the limited understanding of local structure around the tantalum ions, a problem that lies at the heart of predicting the micro- and macroscopic properties of these glasses. Herein, we present a novel approach for predicting the local structural environments in tantalum silicate glass based on a phase diagram approach. The phase relations and glass formation region of Li2O–Ta2O5–SiO2 ternary systems are explored to calculate the structure and additive physical properties of lithium tantalum silicate glasses. These measured and calculated results are in good quantitative agreement, indicating that the phase diagram approach can be applied broadly to Li2O–Ta2O5–SiO2 ternary glass systems. Using the phase diagram approach, the local structure of tantalum can be directly obtained. Each Ta atom is surrounded by six atoms, and its polyhedron, the TaO6 octahedron, bonds through oxygen to Li and Ta. As a network modifier, Ta5+ depolymerizes the silicate glass structure by modulating the local structure of lithium atoms in Li2O–Ta2O5–SiO2 ternary glass system. The compositional dependence of structure in lithium tantalum silicate glasses is quantitatively determined based on the structure of the nearest neighbor congruent compound through the lever rule. These findings offer a precise prediction of tantalum silicate glass properties with quantitative control over local structural environment of the disordered materials. 相似文献
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S. V. Degtyarev A. A. Man'shina A. V. Kurochkin D. V. Zhuzhel'skii Ya. G. Grigor'ev Yu. S. Tver'yanovich 《Glass Physics and Chemistry》2001,27(3):209-213
The results of spectral measurements and the differential thermal analysis (DTA) data for glasses in the Ga2S3–GeS2–Nd2S3system are presented. The boundaries of the glass formation region in the Ga2S3–GeS2–Nd2S3system are determined. It is shown that the luminescence efficiency increases with an increase in the gallium sulfide content due to the displacement of the concentration quenching boundary of Nd3+luminescence with a change in the glass matrix composition. 相似文献
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《应用陶瓷进展》2013,112(4):227-231
AbstractGlass ceramics in the Li2O–Al2O3–SiO2 system have been synthesised to produce bulk materials grown in a glass phase via quenching followed by controlled crystallisation. The crystallisation and microstructure of Li2O–Al2O3–SiO2 (LAS) glass–ceramic with nucleating agents (B2O3 and/or P2O5) are investigated by differential thermal analysis, X-ray diffraction and scanning electron microscopy and the effects of B2O3 and P2O5 on the crystallisation of LAS glass are also analysed. The introduction of both B2O3 and P2O5 promotes the crystallisation of LAS glass by decreasing the crystallisation temperature and adjusting the crystallisation kinetic parameters, allows a direct formation of β spodumene phase and as a result, increases the crystallinity of the LAS glass ceramic. Microstructural observations show that the randomly oriented, nanometre sized crystalline is found with residual glass concentrated at crystallite boundaries. Furthermore, it is interesting that codoping of B2O3 and P2O5 creates not much effect on the crystallisation temperature. The dielectric properties of the glass–ceramics formed through controlled crystallisation have a strong dependence on the phases that are developed during heat treatment. The dielectric constant is continuously increased and the dielectric loss is decreased with addition of additives where mobile alkali metal ions (e.g. Li+) are incorporated in a crystal phase and minimise the residual glass phase. 相似文献