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ratio of citrate/nitrate (1~3) and calcination temperature of 850 ℃ for 1 h, M-type BaGdxFe12-xO19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA*m-1 at x=1.0, which is far greater than that of barium ferrite (BaFe12O19). Key words:materials science; sol-gel method; permanent ferrite; citrate; ultrafine powders; rare earths; [全文内容正......
不同气氛下柠檬酸铁制备铁氧化物的研究 夏笑虹1,刘洪波1,何月德1,石磊1 (1.湖南大学,材料科学与工程学院,湖南,长沙,410082) 摘要:以柠檬酸铁为原料,分别在富氧和无氧气氛中经热处理得到铁氧化物,利用TG技术研究了柠檬酸铁在不同气氛下的热解过程,采用XRD技术研究了不同气氛下柠檬酸铁反应温度与反应时间对产物组分,结构的关系.结果表明:柠檬酸铁在空气气氛的热解产物为Fe_3O_4,提高反应温度或延长反应时间均有利于Fe_3O_4向α-Fe_2O_3的转变.然而,柠檬酸铁在无氧气氛的热解产物为Fe_3O_4与无定形热解炭,增加反应温度和/或延长反应时间会促进Fe_3O_4向Fe,FeO的转变. 关键词:柠檬酸铁; 铁氧化物; 热处理; ferric citrate; iron oxide; heat-treatment; [全文内容正在添加中] ......
硫酸盐电沉积Zn-Fe合金工艺的研究 王先友1,周益春2,杨才千2,龙志林2 (1.湘潭大学化学化工学院 411105;2.湘潭大学物理系 411105) 摘要:通过正交试验研究了酸性硫酸盐体系电沉积低铁含量的Zn-Fe合金镀层工艺,结果表明该体系的镀液配方简单,镀液稳定,操作简便,成本低廉.以柠檬酸钠和柠檬酸分别为络合剂和缓冲剂的镀液pH值稳定.通过Hull槽试验还发现,该镀液的电流密度范围宽,镀层结晶细致,光亮平整. 关键词:电沉积工艺; Zn-Fe合金; 硫酸盐; [全文内容正在添加中] ......
methanesulfonate; tri(2-ethylhexyl) citrate; esterification; catalytic activity; [全文内容正在添加中] ......
-chao, YANG Hai-yu, LI Lei, YANG Jia-kuan (College of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China) Abstract: The lead citrate precursors were prepared at room temperature with citric acid as the main leaching agent combined with other additives such as sodium citrate and H2O2. The ultrafine lead oxide powder was prepared from......
·2H2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO3)2) and sodium oxalate(Na2C2O4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments......
be fabricated at 750-900 ℃ in different citrate acid molar proportions for 0.2-1.0. For all the oxides, both the Seebeck coefficients S and the electrical conductivitiesκincrease with the increasing... to the thermal conductivity κ. The citrate acid molar proportions have a large influence on the particle sizes, which influences the thermoelectric properties of the ceramics. The figure of merit increases......
of phosphates, i.e. sodium tripolyphosphate, sodium trimetaphosphate and trisodium phosphate with different structures was investigated through sedimentation tests of monomineral and artificial mixed mineral... metaphosphates. The dispersion capability of three kinds of phosphates from strong to weak is sodium tripolyphosphate, sodium trimetaphosphate and trisodium phosphate. The different structures of phosphates......
state(SS) and citrate gel(CG) methods. The PL intensity of phosphors increases with the increase of x value in Y0.9-xGdxEu0.1BO3(prepared by SD) due to an energy migration process like Gd3+-(Gd3...) with spherical shape and smooth surface. Furthermore, the spray drying-derived phosphors have higher photoluminescence(PL) intensity than those by citrate gel method, but still a little lower than those......
柠檬酸法合成的Ni-Zn铁氧体粉末的结构与电磁性能 冯则坤1,胡昌吉1,何华辉1 (1.华中科技大学,电子科学与技术系,湖北,武汉,430074) 摘要:用柠檬酸法合成了不同组分的Ni-Zn铁氧体粉末,利用XRD,SEM分析手段对铁氧体粉末的结构和形貌进行了研究,利用网络分析仪测量了微波频段铁氧体粉末的电磁参数,考察了铁氧体组分变化对其电磁参数的影响.结果表明,用柠檬酸法合成的铁氧体粉末的ε′随测试频率的提高变化很小,随铁氧体中Zn含量的增大而减小;而ε″的值一直保持很小;μ′在2~9GHz范围内随铁氧体中Zn含量的增加而减小,而在9~18GHz范围内则变化很小;μ″基本随铁氧体中Zn含......
