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目前,工业产品的三元正极材料LiNi0.5Co0.2Mn0.3O2通常使用间接共沉淀和高温固相烧结相结合的方法.共沉淀制得的氢氧化镍钴锰前驱体,其形貌和粒径分布等直接影响着三元材料LiNi0.5Co0.2Mn0.3O2的性能.使用X射线衍射(XRD)、扫描电镜(SEM)表征和观察材料晶体结构和表面形貌,并测试粒径分布、振实密度和电化学性能,考察三种前驱体对制得的三元材料的影响.研究结果表明,前驱体的粒径分布直接影响材料的物理性能,表面有大量微孔而又致密的球形是较理想的前驱体形貌;焙烧后可得到结晶度高的材料,0.2C全电池放电比容量达到156.4 mAh·g-1,循环寿命优异,300周期循环其容量基本不衰减,500周期循环后容量保持率高达92%. 相似文献
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以氯化亚铜,硝酸锌,氯化锡和硫脲作为反应前驱体,聚乙二醇作为模板,利用溶剂热方法合成Cu2ZnSnS4中空球。其中,聚乙二醇对于产物的最终形成起到关键作用。文章讨论了Cu2ZnSnS4中空球的生长机制,并通过X射线衍射(XRD)、拉曼光谱、场发射电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)、X射线光电子谱(XPS)、选区电子衍射谱(SAED)和紫外-可见光分光光度计(UV-Vis)等技术对样品的微结构以及光学性质进行了表征和分析。结果显示Cu2ZnSnS4中空球为四方晶体,尺寸为600 nm。其禁带宽度为1.52 eV,适用于制作光伏器件。 相似文献
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以氯化亚铜,硝酸锌,氯化锡和硫脲作为反应前驱体,聚乙二醇作为模板,利用溶剂热方法合成Cu2ZnSnS4中空球。其中,聚乙二醇对于产物的最终形成起到关键作用。文章讨论了Cu2ZnSnS4中空球的生长机制,并通过X射线衍射(XRD)、拉曼光谱、场发射电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)、X射线光电子谱(XPS)、选区电子衍射谱(SAED)和紫外-可见光分光光度计(UV-Vis)等技术对样品的微结构以及光学性质进行了表征和分析。结果显示Cu2ZnSnS4中空球为四方晶体,尺寸为600 nm。其禁带宽度为1.52 eV,适用于制作光伏器件。 相似文献
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以尿素替代水为溶剂,采用改良的尿素水解法制备不同结构的CeOHCO3和CeO2,并运用N2吸附-脱附、X射线衍射、H2程序升温还原、O2程序升温脱附、X射线光电子能谱、扫描电镜及甲烷燃烧反应对CeO2催化剂进行表征和催化性能测试.结果表明,CeO2催化性能和前驱体CeOHCO3的晶相结构(六方相或八面体相)存在直接关系.与以八面体为前驱体制得的颗粒状CeO2相比,以六方相为前驱体制得的棒状CeO2具有比表面积大、氧化还原能力强、表面氧空缺浓度高以及催化甲烷燃烧活性高的特点. 相似文献
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采用高温熔融法制备Eu3+?Tb3+共掺杂SiO2?B2O3?Na2O?Y2O3?P2O5前驱体玻璃。对前驱体玻璃粉末进行差示扫描量热(DSC)分析,确定玻璃陶瓷样品的热处理温度。前驱体玻璃热处理后,采用X射线衍射(XRD)和扫描电镜(SEM)分析可知前驱体玻璃中有Na3.6Y1.8(PO4)3晶粒析出。利用荧光光谱对玻璃陶瓷样品的发光性能进行表征,同时分析了Tb3+离子的荧光衰减曲线,确定Eu3+、Tb3+离子的发光机理以及能量传递过程。通过对Eu3+?Tb3+共掺杂玻璃陶瓷样品的发射光谱采集并用色坐标软件和色温计算程序,获得玻璃陶瓷样品的色坐标和相关色温。 相似文献
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采用溶胶-凝胶法制备CaO-P2O5-SiO2-Na2O-B2O3体系前驱体粉末,用CaF2替代部分CaO再次制备前驱体粉末。 通过TG-DSC分析确定结晶温度为865 ℃,经过热处理获得主晶相为Na6Ca3Si6O18的玻璃陶瓷。 通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)等技术手段及体外生物活性实验分析玻璃陶瓷的显微结构及性能。 结果表明,CaF2的加入能提高玻璃陶瓷的体积密度、抗折强度和弹性模量,并且不会破坏玻璃陶瓷的生物活性。 相似文献
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Valerie F. Allen Ronald Mason Peter B. Hitchcock 《Journal of organometallic chemistry》1977,140(3):297-307
X-ray crystallographic analyses of H2Os3(CO)10, H(SC2H5)Os3(CO)10 and (OCH3)2Os3(CO)10 are reported. Although hydrogen atom positions have not been located, the essential isostructural nature of the three commplexes establishes the hydride ligands as bridging two metal atoms, separated by 2.670 Å, with a formal bond order of two; the bridging hydrido- and thiolato-ligands span an osmium---osmium bond of length 2.863 Å and formal bond order one; the two μ-methoxy ligands bridge two metal atoms separated by 3.078 Å which, by simple 18 electron rule counting, has a metal---metal bond order of zero. Some general comments are made on the structures of polynuclear transition metal carbonyls. 相似文献
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C.R. Mariappan 《Journal of solid state chemistry》2006,179(2):450-456
The nanostructured NASICON-type LiTi2(PO4)3 (LTP) material has been synthesized by Pechini-type polymerizable complex method. The use of water-soluble ammonium citratoperoxotitanate (IV) metal complex instead of alkoxides as precursor allows to prepare monophase material. Thermal analyses have been carried out on the powder precursor to check the weight loss and synthesis temperature. X-ray powder diffraction analysis (XRD) has been performed on the LTP powder obtained after heating the powder precursor over a temperature range from 550 to 1050 °C for 2 h. By varying the molar ratio of citric acid to metal ion (CA/Ti) and citric acid to ethylene glycol (CA/EG), the grain size of the LTP powder could be modified. The formation of small and well-crystalline grains, in the order of 50-125 nm in size, has been determined from the XRD patterns and confirmed by transmission electron microscopy. 相似文献
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The title compound can be prepared in good yield by heating either [Ru4(μ-H)4(CO)12] or [Au2Ru4(μ3-H)2(CO)12(PPh3)2] with [AuMe(PPh3)] in toluene. The related compound [Au3Ru4(μ3-H)(μ-dppm)(CO)12(PPh3)] has also been prepared. Both trigoldtetraruthenium clusters undergo dynamic behaviour in solution, involving intramolecular rearrangement of the metal core, as revealed by variable temperature NMR studies. The crystal structure of [Au3Ru4(μ3-H)(CO)12(PPh3)3] has been established by an X-ray diffraction study. The metal atom core comprises a trigonal bipyramidal AuRu4 unit with two AuRu2 faces capped by gold atoms. 相似文献
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We report a low temperature synthesis of layered Na0.20Co02 and K0.44CoO2 phases from NaOH and KOH fluxes at 400°C. These layered oxides are employed to prepare hexagonal HCoO2, LixCoO2and Delafossite AgCoO2 phases by ion exchange method. The resulting oxides were characterised by powder X-ray diffraction, X-ray photoelectron spectroscopy,
SEM and EDX analysis. Final compositions of all these oxides are obtained from chemical analysis of elements present. Na0.20Co02 oxide exhibits insulating to metal like behaviour, whereas AgCoO2 is semiconducting.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
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CoFe2O4/TiO2 magnetic composite films were prepared using the sol-gel method with tetrabutyltitanate and metallic chlorates as starting
materials. The effects of heat treatment temperatures on microstructures and on magnetic properties were studied. The microstructure
and properties of the samples at different heat treatment temperatures were characterized by X-ray diffraction, Raman spectrum,
scanning electron microscopy, polarized microscopy and vibrating sample magnetometry. The results show that crystals of different
substances grow up independently. Cobalt ferrite is evenly embedded into the titanium dioxide matrix in the prepared composite
films. The magnetism of the composite films is enhanced with an increase of the heat temperature.
Supported by the National Natural Science Foundation of China (Grant Nos. 50632030 and 10474077), and the Natural Science
Foundation of Shaanxi Province (Grant No. 2006E135) 相似文献
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The results of the X-ray structural study for the K4LiH3(SO4)4 single crystal are presented at a wide temperature range. The thermal expansion of the crystal using the X-ray dilatometry and the capacitance dilatometry from 8 to 500 K was carried out. The crystal structures data collection, solution and refinement at 125, 295, 443 and 480 K were performed. The K4LiH3(SO4)4 crystal has tetragonal symmetry with the P41 space group (Z=4) at room temperature as well as at the considered temperature range. The existence of a low-temperature, para-ferroelastic phase transition at about 120 K is excluded. The layered structure of the crystal reflects a cleavage plane parallel to (001) and an anisotropy of the protonic conductivity. The superionic high-temperature phase transition at TS=425 K is isostructural. Nevertheless, taking into account an increase of the SO4 tetrahedra libration above TS, a mechanism of the Grotthus type could be applied for the proton transport explanation. 相似文献
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A method of synthesis of some metal ortho-tellurates of the type Me3TeO6 and Me2TeO6 was developed. Crystallographic data (parameters of the elementary cell and the number of the formula units of these compounds) were calculated. Their picnometric density and X-ray density were determined and compared. The thermostability of these ortho-tellurates was studied. 相似文献
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V. V. Gurzhiy P. A. Mikhailenko S. V. Krivovichev I. G. Tananaev B. F. Myasoedov 《Russian Journal of General Chemistry》2012,82(1):23-26
Crystals of a new uranyl selenate complex [CH3(CH2)3NH3](H5O2)[(UO2)2(SeO4)3(H2O)] were obtained by isothermal evaporation at room temperature of its aqueous solution. The crystal structure was determined
by the X-ray diffraction analysis. The observed character of the arrangement of organic molecules in the interlayer space
confirms the concept of hydrophilic and hydrophobic zones. 相似文献
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Masao Matsuoka Tsuyoshi Matsuda June Tamaki Yoshifumi Yamamoto Chiaki Iwakura 《Research on Chemical Intermediates》2006,32(5):389-402
Laves-phase hydrogen storage alloy has a high potential for use as negative electrode material as alternative for the misch-metal-based
material. In order to improve the energy density and the rate capability of negative electrode, chemical and mechanical modification
of Lavesphase alloy with different stoichiometric ratios was carried out. Discharge capacity and high-rate dischargeabilty
was evaluated by electrochemical methods and the characterization of Laves-phase alloy was made by X-ray diffraction, SEM
observation and PCT measurement. The best result in discharge capacity could be obtained for stoichiometric Laves-phase alloy
with a composition of Zr0.9Ti0.1Ni1.1Co0.1Mn0.5V0.2Cr0.1 by boiling in 10 M KOH solution. On the other hand, the high-rate dischargeability was increased remarkably by introducing
mechanical grinding before alkali treatment. The cause for improved performance was discussed on the basis of thermodynamic
stability of metal hydride and changes in crystal structure and surface morphology influencing on diffusion coefficient and
diffusion path length of hydrogen. 相似文献
20.
Yun-Hui Huang Ke-Feng Huang Lian-Long He Chun-Sheng Liao 《Journal of solid state chemistry》2003,174(2):257-263
Granular Ag-added La0.7Ca0.3MnO3 (LCMO) samples were prepared by a sol-gel chemical route. Significant enhancements in Curie temperature (TC), metal−insulator transition (Tp) and magnetoresistance (MR) effects near room temperature are observed in as-obtained samples. 10 wt% addition of Ag in LCMO causes TC shift from 272 to 290 K, Tp boost up for more than 100 K and resistivity decrease by more than 3 orders of magnitude. X-ray diffraction patterns, thermal analysis and energy dispersive analysis of X-rays evidently show the existence of metal silver in LCMO matrices. High-resolution electron microscopy illustrates a well crystallization for LCMO grains in existence of Ag. It is argued that improved grain boundary effect and better crystallization caused by Ag addition are responsible for the enhancements. 相似文献