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Jafar Baseri Rahim Naghizadeh Hamid Reza Rezaie Farhad Golestanifard Mohammad Golmohammad 《International Journal of Applied Ceramic Technology》2020,17(6):2709-2715
CoAl2O4 spinel was successfully synthesized by combustion synthesis method using glycine and urea by 1:1 molar ratio as fuels and sol-gel process using citric acid as a chelating agent. The as-synthesized powders were calcined at desired temperatures to obtain CoAl2O4 spinel as a single phase. X-ray diffraction, thermogravimetric, and differential thermal analysis results revealed that the formation of CoAl2O4 spinel in combustion method needs 300°C higher temperatures than those of sol-gel. Scanning electron microscopy and transmission electron microscopy analysis results revealed that “sol-gel spinel” had nanometric particle size which was smaller than those of “combustion spinel.” Temperature programed reduction with hydrogen and Fourier transform infrared spectroscopy results declared that there was a little residual cobalt oxide in combustion spinel while there is no oxide resided in “sol-gel spinel.” Consequently, the sol-gel method has more benefit in synthesizing spinel with sulfate precursors than combustion. 相似文献
3.
Pengcheng Zhao Yu Xiang Yan Xu Yuehua Wen Wenfeng Zhang Xiayu Zhu Meng Li Zhaoqing Jin Hai Ming Gaoping Cao 《Ceramics International》2018,44(8):9105-9111
Garnet-type Li5La3Ta2O12 (LLTaO) solid electrolyte is a potential candidate component for future all-solid-state batteries due to its extraordinary stability against the reaction with molten lithium. In contrast with traditional cold isostatic pressing (CIP) method, which generally pursues ultra-high pressure, this paper tries to enhance the density and ionic conductivity of LLTaO by self-consolidation strategy without the assistance of any pressing operations. A LLTaO bulk with a relative density of 95% is obtained. SEM images reveal that the bulk sample is assembled by large dense particles in size of tens of microns indicating that the interstitial space among the particles has been dramatically minimized. Accordingly, the total ionic conductivity and the bulk ionic conductivity at 30?°C are promoted up about one order of magnitude higher to 2.63?× 10?5 S?cm?1 and 1.41?×?10?4 S?cm?1, respectively. Moreover, the lithium ionic migration network in the crystalline unit cell of LLTaO is first explored from its assembled way. A hexagon-like basic unit with tetrahedral Li1 joint sites and Li1- - Li1 edges is identified. The tetrahedral Li1 sites act as crucial junctions for the transportation of lithium ions. This work would significantly stimulate the development of LLTaO electrolyte membrane technology. 相似文献
4.
Gd and Al co-doped LiMn2-x(GdAl)xO4 (x?=?0, 0.01, 0.02, 0.03, 0.04 and 0.05) materials with spinel structure were synthesized by sol–gel method. Powder X-ray diffraction results confirm the formation of cubic spinel structure and average particle sizes are found to be between 80 and 110?nm from FE-SEM and TEM analysis. Decrease in peak potential difference as a function of doping in Cyclic Voltammetry results establishes enhancement in Li+ intercalation and de-intercalation. Electrochemical Impedance Spectroscopy (EIS) results showed that accumulation of charges on electrode has improved with doping over pristine samples. At a doping of x?=?0.02 charge transfer resistance values were found to be least. First cycle charge–discharge profiles for LiMn1.96(GdAl)0.02O4 shows 139.2?mAh/g discharge capacity over other doped derivatives and pure LiMn2O4 (119.6?mAh/g) in aqueous Li2SO4 electrolyte. Doping of x?=?0.02 exhibit good cycling performance with only a total 4% capacity loss after 30 cycles. 相似文献
5.
Katerina Zaharieva Maya Shopska Ilyana Yordanova Sonia Damyanova 《Ceramics International》2018,44(1):326-332
Magnesium aluminate-based materials were prepared by applying different methods: (i) mechanochemical milling of the initial mixture of magnesium and aluminium nitrate powders (in appropriate stoichiometric amounts) followed by heat treatment at temperatures of 650 °C and 850 °C and (ii) melting of the mixture of nitrate precursors at 240 °C followed by thermal treatment at 650 °C, 750 °C and 850 °C. The effect of synthesis method on the structure and morphology of the obtained solids was studied by using various techniques such as: nitrogen adsorption-desorption isotherms, powder XRD, IR spectroscopy and SEM. It was shown that the mechanochemical milling performed before calcination procedure leads to obtaining of nanocrystalline magnesium aluminate spinel phase at lower temperature of 650 °C in comparison with the method using thermal treatment only (at 750 °C). The obtained nanomaterials exhibit mesoporous structure. 相似文献
6.
Pengcheng Zhao Yu Xiang Yuehua Wen Meng Li Xiayu Zhu Songtong Zhao Zhaoqing Jin Hai Ming Gaoping Cao 《Journal of the European Ceramic Society》2018,38(16):5454-5462
Garnet-like Li7La3Zr2O12 electrolytes with Nb doping are synthesized by self-consolidation method. Different from conventional methods such as cold or hot isostatic pressing, not any pressing assistance is employed throughout the preparation process. Although the preparation process is dramatically simplified, both density and ionic conductivity of the obtained samples are enhanced. Nb-doped content plays a key role in the sintering of the packed precursor powders and in the structure stabilization of the obtained bulk samples. The optimized 0.60?mol Nb-doped sample with relative density of 94%, fine particle boundaries, and solitary cubic structure possesses the maximum total ionic conductivity of 5.22?×?10?4?S?cm?1 at 30?°C, which is comparable to the highest reported value of the samples prepared by conventional pressing methods. This work verifies that self-consolidation strategy is effective, reliable, and productive for the preparation of cubic Li7La3Zr2O12 electrolyte, which would significantly facilitate the development of ceramic electrolyte membrane technology. 相似文献
7.
This paper reports for the first time, synthesis of NiCo2O4 nano spinel by green oxidative precipitation and its performance in photocatalytic desulfurization of dibenzothiophene (DBT) from gas oil model at different process conditions under visible light. The as-produced nanostructure was characterized by X-ray diffraction, Fourier transform infrared, UV–VIS diffuse reflective spectroscopy, energy-dispersive X-ray spectrometry and scanning electron microscopy. The experiments for the study of different photocatalytic conditions were designed by response surface methodology and a second-order regression model was developed with a determination coefficient (R2) of 0.9769. Pareto analysis predicted that the relative importance of process factors for DBT removal is as follows: irradiation time?>?reaction temperature?>?photocatalyst dosage?>?DBT concentration. The promising results for DBT removal were concluded by photo desulfurization over the nano spinel. The study confirmed that nano spinels could be an alternative and cheap photocatalyst for desulfurization from the oil products. 相似文献
8.
高性能阴极材料的开发对推动中温固体氧化物燃料电池(intermediate temperature solid oxide fuel cells, IT-SOFCs)的发展具有重要意义。本文采用溶胶-凝胶法制备了尖晶石型NiMn2O4(NMO)电子-离子混合导体材料,并作为IT-SOFCs阴极进行了系统的研究,通过X射线衍射表征确定NMO材料呈稳定的立方相结构,并采用电导弛豫方法对其氧离子传导能力进行了研究。发现NMO具有优秀的氧离子传导能力,为其电化学性能提供了保障。对称电池的电化学阻抗谱测试结果表明,800℃时NMO阴极材料的界面电阻值为0.27 Ω·cm-2,同时作为阳极支撑型SOFC的阴极材料进行放电时的最大功率密度可以达到864.9 mW·cm-2。上述结果表明,NiMn2O4是一种极具潜力的IT-SOFCs阴极材料。 相似文献
9.
《International Journal of Hydrogen Energy》2020,45(27):13841-13847
The catalysts are often used in fuel cells and metal-air batteries to speed up electrochemical reactions. In this study, we prepared CoFe2O4 nanoparticles with mainly inverse spinel structure and FeCo2O4 nanoparticles with mainly spinel structure as bifunctional catalysts by hydrothermal method. After annealing at 350 °C, pure CoFe2O4 and FeCo2O4 nanoparticles with uniform size distribution have been obtained. The CoFe2O4 nanoparticles showed high current density of 5.5 mA/cm2 at −0.8 V in the ORR test. It's low Tafel slope of 83.0 mV/dec further confirmed the excellent ORR catalytic properties of CoFe2O4 nanoparticles. Furthermore, the CoFe2O4 nanoparticles also showed good OER properties with satisfied current density of 35.7 mV/cm2 at l.0 V and low OER Tafel slope of 71.0 mV/dec. Both the ORR and OER properties of CoFe2O4 nanoparticles showed good time stability which were compared with FeCo2O4 nanoparticles. These results indicated that CoFe2O4 nanoparticles with mainly inverse spinel structure had better electrocatalytic performance than FeCo2O4 nanoparticles with mainly spinel structure. The CoFe2O4 nanoparticles with mainly inverse spinel structure show a significant potential application in rechargeable battery. 相似文献
10.
摘要:在含铬铁水转炉冶炼过程中,Cr很容易被氧化成Cr2O3进入渣中,并与渣中其他成分反应生成高熔点含铬尖晶石。采用FactSage热力学软件计算了CaO-SiO2-FeO-Cr2O3-MgO-MnO转炉渣系在冶炼温度1300~1700℃下的物相组成,研究了Cr2O3、FeO和碱度对炉渣中尖晶石相含量的影响规律。研究结果表明,温度和渣系成分都会影响炉渣的物相组成。渣系中含有Cr2O3时,物相中均含有MgCr2O4、FeCr2O4和MgFe2O4尖晶石相,尖晶石相的总含量随着Cr2O3和碱度的增加而增加,随着炉温的升高而减少。温度为1300~1500℃时,炉渣中尖晶石含量随着FeO的增加而增加;温度为1500~1700℃时,尖晶石含量随着FeO的增加而略有减少。在温度小于1500℃的转炉冶炼前中期,炉渣物相组成中尖晶石相所占比例较大,易造成化渣不良或者炉渣粘稠,影响转炉冶炼工艺的顺行。 相似文献