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81.
《中国稀土学报(英文版)》2022,40(10):1509-1518
Gd2O3:Eu3+@CsPbBr3 quantum dots (QDs) mesoporous hollow nanocomposites with good luminescent properties and high stability were built. Among which, the hollow Gd2O3:Eu3+ spheres and CsPbBr3 QDs were prepared by urea homogeneous precipitation and hot-injection method, respectively. Finally, the Gd2O3:Eu3+@CsPbBr3 QDs shell–core compounds were constructed through mechanical stirring. The structure, morphology, stability and luminescent properties were studied by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry/thermogravity (DSC/TG), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence excitation/photoluminescence (PLE/PL) and life decay tools. Compared to the original CsPbBr3 QDs, Gd2O3:Eu3+@CsPbBr3 QDs display better photostability, thermal stability and current stability. The resulting Gd2O3:Eu3+@CsPbBr3 QDs composite exhibits good yellow emission. The Gd2O3:Eu3+@CsPbBr3 QDs mixed silicone resin was directly coated on the blue LED chip, then the w-LED device with the color coordinate of (0.31, 0.32) was successfully assembled. The Gd2O3:Eu3+@CsPbBr3 QDs compounds with excellent luminescent properties and stability are expected to be widely used in lighting and display areas. 相似文献
82.
《中国稀土学报(英文版)》2022,40(12):1899-1904
To improve the coercivity and temperature stability of Nd-Fe-B sintered magnets for high-temperature applications, the eutectic Tb80Fe20 (wt%) alloy powders were added into the Nd-Fe-B sintered magnets by intergranular method to enhance the coercivity (Hcj) and thermal stability. The microstructure, magnetic properties and thermal stability of the Nd-Fe-B magnets with different Tb80Fe20 contents were studied. The experimental results demonstrate that the coercivity (Hcj) of the sintered Nd-Fe-B magnet is significantly enhanced from 14.12 to 27.78 kOe, and the remanence (Br) decreases not obviously by introducing 4 wt% Tb80Fe20 alloy. Meanwhile, the reversible temperature coefficients of coercivity (β) and remanence (α) of the Nd-Fe-B magnets are increased from ?0.5634%/℃ to ?0.4506%/℃ and ?0.1276%/℃ to ?0.1199%/℃ at 20–170 ℃, respectively. The Curie temperature (TC) of the Nd-Fe-B magnet is slightly enhanced with the increase of Tb80Fe20 content. Moreover, the irreversible flux magnetic loss (hirr) is obviously reduced as Tb80Fe20 addition increases. Further analysis of the microstructure reveals that a modified microstructure, i.e. clear and continuous RE-rich grain boundary layer, is acquired in the sintered magnets by introducing Tb80Fe20 alloy. The associated mechanisms on improved coercivity and thermal stability were comprehensively researched. 相似文献
83.
Xinhua Wang Changyao Wang Changpin Chen Qidong Wang 《Journal of Alloys and Compounds》2006,420(1-2):107-110
In this paper, we deduced an empirical equation for predicting the stabilities of the hydrides of AB5-type compounds with the consideration of the effects of geometrical factor and electric factor. The theoretical curves derived from this equation are in good agreement with the test results of La1−xCaxNi5, Ml1−xCaxNi5 and La1−xCexNi5 compounds. With this model, we can easily interpret the phenomenon that the initial partial substitution of R by Ca in R1−xCaxNi5 (R is rare earth metal) compounds cause an increase of hydrogen desorption pressure to a maximum value, whereas in the range of larger Ca content x the hydrogen desorption pressure decreases with increasing x. 相似文献
84.
Diffusion and reaction models of varying complexity are used to study the stability of the combustion of single char particles. In contrast to past studies which have considered only the reaction of carbon with oxygen, both the heterogeneous reactions of carbon with oxygen and carbon dioxide and the homogeneous oxidation of carbon monoxide are taken into account in the formulation of the mathematical models. Emphasis is placed on the investigation of the feasibility of occurrence of oscillatory combustion. Our results show that high rates of the C-O2 reaction and high concentration of O2 in the ambient favor the occurrence of multiple steady states and oscillatory solutions, but the appearance of oscillatory instability is suppressed by the homogeneous reaction in the gas phase and the presence of CO and CO2 in the ambient. The parametric investigation of the problem reveals, in agreement with the results of past studies, that the heat capacity of the porous solid, the Lewis number, and the thickness of the stagnant film are three key parameters for the occurrence of the oscillatory response of the system. Reasonably large values of solid heat capacity practically eliminate the possibility of oscillatory combustion, but an appropriate combination of large values of stagnant film thickness and small Lewis numbers may offset the effect of solid heat capacity 相似文献
85.
In this paper we describe an apparatus for reproducibly measuring thermal shock resistance of thick polymer layers bonded to metals. The thermal shock behavior is discussed in terms of epoxy samples bonded to an aluminum substrate. It was found that both high resin toughness and low resin thermal expansion coefficient improved thermal shock resistance of thick coatings, but only a sample containing 60wt. % glass beads did not develop a failure crack. Effects of sample thickness, temperature gradient, and resin composition on thermal shock behavior are discussed. 相似文献
86.
微粉对矾土基超低水泥浇注料性能的影响 总被引:1,自引:3,他引:1
以高铝矾土熟料为主原料 ,加入 2 %的铝酸钙水泥及总量为 6 %的Al2 O3 微粉和SiO2 微粉 ,配制了矾土基超低水泥浇注料 ,研究了微粉对浇注料的烧结性能、力学性能及热震稳定性的影响。结果表明 :(1 )SiO2 微粉对浇注料的促烧结作用优于Al2 O3 微粉。这是因为与Al2 O3 微粉相比 ,由气相沉积生成的SiO2微粉的粒度小 ,比表面积大 ,活性较高。 (2 )随着SiO2微粉加入量的增加 ,在 1 1 0 0℃和 1 4 0 0℃处理后的常温强度以及在 1 30 0℃和 1 4 0 0℃下的高温抗折强度和抗热震性明显提高。这是由于引入的SiO2 微粉在高温下与Al2 O3 反应生成的针状莫来石穿插进入刚玉骨架 ,起着明显的强化和韧化作用 相似文献
87.
Shape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH)2 to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH)2. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing
effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at
elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices. 相似文献
88.
M. Bilal Banaras Khan H.A. Rahnamaye Aliabad M. Maqbool S. Jalai Asadabadi I. Ahmad 《Computer Physics Communications》2014
Thermoelectric properties of two antiperovskites SbNCa3 and BiNCa3 are calculated using first principles calculations. High values of Seebeck coefficients are observed for these materials. Electrical and thermal conductivities are also calculated. Increase in thermal conductivity and decrease in electrical conductivity are found with increasing temperature. The maximum values of thermal conductivity are 92×1014 W/m K s and 88×1014 W/m K s for SbNCa3 and BiNCa3 respectively at a temperature of 900 K. The peak values of 5×1020/Ω m s and 5.2×1020/Ω m s are achieved for n-type SbNCa3 and BiNCa3 respectively at a temperature of 300 K. Figure of merit is achieved for these materials at room temperature which shows that these materials can be useful for thermoelectric devices and alternative energy sources. 相似文献
89.
PC/PA1010共混物的热行为 总被引:2,自引:0,他引:2
利用热失重、微分热失重和显示扫描量热法研究了聚碳酸酯/尼龙1010共混物的热行为和解降解过程。结果表明:共混物在600℃以下分两步降解,降解温度随尼龙1010用量增加有下降趋势;共混物的熔点随尼龙1010用量增加而升高。 相似文献
90.
《Calphad》2014
Experimental investigations and Gibbs energy modelling of KCl–LiCl–UCl3 system employing CALPHAD method are reported. Gibbs energy modelling of the subsystems KCl–UCl3 and LiCl–UCl3 was carried out primarily using phase diagram data from the literature. For the Gibbs energy modelling of the KCl–LiCl subsystem, new phase boundary data corresponding to four terminal compositions , 0.05, 0.95 and 0.97) obtained through differential thermal analysis data along with thermochemical and phase diagram data from the literature were used. Thermal analysis was also carried out for KCl–LiCl eutectic mixture containing small amounts of UCl3 and ). The liquidus temperatures for these compositions were found to be 637 K and 674 K. Electromotive force data for dilute solutions of UCl3 in the KCl–LiCl eutectic melt, measured in the temperature range 708–833 K in the present work, were found to be in good agreement with the literature data. These data were also used as input for the Gibbs energy modelling of the KCl–LiCl–UCl3 system. In order to improve the quality of the resulting Gibbs energy functions of the quasibinaries and the quasiternary, enthalpies of mixing of the corresponding melts estimated using an empirical correlation based on surrounded-ion model were also used as input. Finally, the generated Gibbs energy functions were used to compute phase equilibria. 相似文献