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使用喷雾干燥法制备了Li1+2xMn0.3+xNi0.3-3xCr0.4O2 (x=1/60、1/30、1/20、1/15、1/12)系列样品, 并借助XRD, SEM, ICP, XPS, IR和Raman等手段对所制备系列样品的结构、价态及电化学性能进行了表征。研究表明, Li1+2xMn0.3+xNi0.3-3xCr0.4O2 系列样品均具有典型的富锂层状固溶体型的晶体结构特征, 且在其XRD图谱中未观测到任何杂相的存在。然而, XPS的数据表明Cr3+与Cr6+共存于各个样品中, 且由于Cr6+的存在使得样品表现出强烈的吸湿性。Cr6+可通过水洗处理去除。对于它们的电化学特征而言, 未经水洗处理的样品由于具有强烈的吸湿性, 其电化学性能很差。水洗处理后的系列样品表现出典型的三元富锂层状固溶体的电化学行为, 其首次放电比容量随着样品中Li和Mn含量的增加而增大。样品Li1.17Mn0.38Ni0.05Cr0.4O2的首次放电比容量为203 mA h/g, 50次循环后容量保持率为71%。 相似文献
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β-MxV2O5(M=Li,Na,K)的溶胶凝胶法合成及其高温阴极放电性能 总被引:1,自引:0,他引:1
用柠檬酸盐溶胶-凝胶工艺制取了三种β-MxV2O5氧化物Li0.3V2O5、Na0.33 V2O5和K0.25V2O5;TG和DTA试验显示干凝胶焙烧过程中出现两个吸热峰,中间有一个放热峰;XRD分析表明高温处理时Li0.3 V2O5可氧化成LiV3O8和V2O5,而Na0.33V2O5和K0.25有较好的化学稳定性;模拟Li-B合金/LiCl-KCl/β-MxV2O5(或α-V2O5)热电池500℃放电试验表明β相阴极放电较α相平稳,但初始电压峰值略有降低,β-Li0.3V2O5相因具有较α-V2O5相更通畅的Li+快速扩散通道,且通道内没有Na+或K+大离子对Li+扩散的阻碍,放电最为平稳,有效比容量最高. 相似文献
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Huanfu Zhou Hong Wang Xiaoyan Ding Xi Yao 《Journal of Materials Science: Materials in Electronics》2009,20(1):39-43
A new Li2O–Nb2O5–TiO2 (LNT) ceramic with the Li2O:Nb2O5:TiO2 mole ratio of 3:1:3 has been investigated. The compound is composed of two phases, the Li2TiO3 and “M-phase” solid solution phase. The microwave dielectric ceramic has low sintering temperature (∼1100 °C) and good microwave
dielectric properties of a relatively high permittivity (∼51), high Q × f value up to 8700, and small temperature coefficient (∼37 ppm/°C). The low-amount doping of 0.83Li2O–0.17V2O5 (LV) can effectively lower the sintering temperature from 1100 to 900 °C and induce no obvious degradation of the microwave
dielectric properties. Typically, the 1 wt.% LV-doped ceramic sintered at 900 °C has better microwave dielectric properties
of εr = 51.3, Q × f = 7235 GHz, τ
f
= 22 ppm/°C, which suggests that the ceramics can be applied in microwave LTCC devices. 相似文献
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合成了4种不同铜含量的间苯二甲酰二茂铁二乙酰腙配位聚合物(PFZCu),然后在高温(600~800℃)热解制得粒径为10~25nm的固溶体xCuFe2O4·(1-x)Fe3O4(0相似文献
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简介了上海硅酸盐研究所多年来对F″-Al2O3陶瓷的研究结果。内容包括制备工艺和性能研究两部分。前者涉及原料和稳定剂选择,化学成分和显微结构控制以及烧结工艺等。后者包括β″-Al2O3陶瓷的吸水性和表面性质以及稀土离子交换的研究。 相似文献
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I. Ardelean O. Cozar N. Vedeanu Dorina Rusu C. Andronache 《Journal of Materials Science: Materials in Electronics》2007,18(9):963-966
glass system, with 0 < x
50 mol%, was prepared and investigated by EPR method. For low content of V2O5 all the spectra present a hyperfine structure typical for isolated V4+ ions. With the increasing of V2O5 content, the EPR absorption signal showing hyperfine structure is superposed by a broad line without hyperfine structure
characteristic for clustered ions. At high V2O5 content, the vanadium hyperfine structure disappears and only the broad line can be observed in the spectra.
Spin Hamiltonian parameters g
, g
, A
, A
, dipolar hyperfine coupling parameters, P, and Fermi contact interaction parameters, K, have been calculated.The composition dependence of line widths of the first two absorptions from the parallel band and of
the broad line characteristic to the cluster formations was also discussed. 相似文献
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锂离子电池用正极材料LixCo0.8N0.2O2 总被引:7,自引:0,他引:7
在控制结晶工艺合成LixCo0.8Ni0.2O2的基础上制备了锂离子电池正极材料LixCo0.8Ni0.2O2。能量散射谱分析结果表明活性材料中Co、Ni元素分布均匀。由于在控制结晶合成的前驱体Co0.8Ni0.2(OH)2中,Co、Ni均匀分布在M(OH)2中的M层,因此可以避免形成一般固溶体发生扩散性重组所需长时间的煅烧过程。扫描电子显微镜分析了表微观形貌的变化。X米衍射分析表明LixCo0.8Ni0.2O2为单一相的α-NaFeO2层状结构,不存在其它杂相;晶胞参数a和c随x变化经历了由小到大再变小的;c/a则经历了一个由大到小再变大的过程。 相似文献
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V2O5常压干燥气凝胶薄膜的制备及Li+注入研究 总被引:2,自引:0,他引:2
采用溶胶-凝胶技术制备溶胶,结合提拉法镀膜,通过溶剂替换工艺在常压下制备出了纳米多孔结构的V2O5气凝胶薄膜.使用TEM、BET、椭偏仪分别观测和测试溶胶的形貌、气凝胶孔径分布以及薄膜的折射率和孔洞率.采用标准三电极法研究了薄膜的电化学伏安循环特性以及恒流充放电性质.研究结果表明,常压干燥制备的薄膜孔隙率达到了56%,比干凝胶薄膜提高了16%,而且比容量达到530mAh/g左右,比干凝胶薄膜提高了33%,可逆性也得到了改善.研究表明,这些性能的提高归因于常压干燥气凝胶薄膜较高的孔隙率以及较大的孔洞直径. 相似文献
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A. Sayyadi-Shahraki E. Taheri-Nassaj S. A. Hassanzadeh-Tabrizi H. Barzegar-Bafrooei 《Journal of Materials Science: Materials in Electronics》2014,25(1):355-360
The effects of Li2O–ZnO–B2O3 (LZB) glass additive on the sintering behavior, phase composition, microstructure and microwave dielectric properties of Li2Zn3Ti4O12 ceramics were investigated. The addition of a small amount of LZB glass can reduce the sintering temperature of Li2Zn3Ti4O12 ceramics from 1,075 to 900 °C without much degradation of the microwave dielectric properties. Only a single-phase Li2Zn3Ti4O12 is formed in Li2Zn3Ti4O12 ceramic with LZB addition. Typically, the 1.5 wt% LZB glass-added Li2Zn3Ti4O12 ceramic sintered at 900 °C for 2 h can reach a high relative density of 97.5 % and exhibits good microwave dielectric properties, i.e., relative dielectric constant (ε r ) = 19.1, quality factor (Q) = 7083.5 at 9 GHz, and temperature coefficient of resonant frequency (τ f ) = ? 48.9 ppm/°C. In addition, the ceramic could be co-fired well with an Ag electrode, which is made it as a promising dielectric ceramic for low temperature co-fired ceramics technology application. 相似文献
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本文利用DTA、XRD和SEM对Li2O-Al2O3-SiO2(以下简称LAS)微晶玻璃核化晶化热处理制度及氟离子在该玻璃体系中的作用进行研究.通过分析得出:含氟LAS玻璃核化温度和晶化温度分别为620℃和710℃,比相同组份的不含氟Li2O-Al2O3-SiO2玻璃核化、晶化温度分别降低了40℃和160℃左右;引入氟离子明显降低LAS玻璃析晶温度,系统的活化能降低约54kJ/mol,当含氟LAS玻璃的核化时间为1h、晶化时间为4hrs,平均微晶颗粒尺寸在50nm左右. 相似文献