J.T.Guo
,
S.H. Wang
,
H. Li
,
W.H. Lai and M.H.Tan(Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China Manuscript received 26 August 1996)
金属学报(英文版)
The isothermal oxidation behavior of Ni_3Al containtng 15 at.% Fe and NiAl containing 30 at.% Fe was studied for 100 h at 850, 950, 1050 and 1150℃, respectively. The results show that the oxidation kinetics of the two alloys obey a parabolic law at various temperatures and every parabolic curve possesses two oxidation rate constants. The morphology, microstructure and the chemical composition of the oxide scales were examined using optical metallography, X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis. The oxide scale of Ni_3Al containing 15 at.% Fe consists mainly of NiO, NiFe_2O_4, and FeAl_2O_4, and that of NiAl containing 30 at.% Fe consists of Fe_2O_3 and (Fe,Ni)Fe_2O_4, contrasting sharply to the oxide scales of pure Ni_3Al and NiAl which consist of Al_2O_3. The oxide scales on the surfaces of Ni_3Al and NiAl containing Fe are not too dense and not too cohesive to the matrix,so their oxidation resistance is not too good.
关键词:
:oxidation
,
null
,
null
,
null
Journal of Materials Research
The effect of Li(3)N additive on the Li-Mg-N-H system was examined with respect to the reversible dehydrogenation performance. Screening Study with varying Li(3)N additions (5, 10, 20, and 30 mol%) demonstrates that all are effective for improving the hydrogen desorption capacity. Optimally, incorporation of 10 mol% Li(3)N improves the practical capacity from 3.9 wt% to approximately 4.7 wt% hydrogen at 200 degrees C, which drives the dehydrogenation reaction toward completion. Moreover, the capacity enhancement persists well over 10 de-/rehydrogenation cycles. Systematic x-ray diffraction examinations indicate that Li(3)N additive transforms into LiNH(2) and LiH phases and remains during hydrogen cycling. Combined structure/property investigations suggest that the LiNH(2) "seeding" should be responsible for the capacity enhancement, which reduces the kinetic barrier associated with the nucleation of intermediate LiNH(2). In addition, the concurrent incorporation of LiH is effective for mitigating the ammonia release.
关键词:
complex hydrides;improvement;mixtures;imides;amide;h-2
Journal of Physical Chemistry C
The Li-Mg-N-H system was prepared by reacting magnesium amide [Mg(NH(2))(2)] with lithium nitride (Li(3)N) and investigated with regard to the hydrogen storage properties. Our study shows that the present method is superior to the conventional route in enhancing the reversible dehydrogenation properties. Through optimizing the Li(3)N:Mg(NH(2))(2) ratio in the starting materials, the reversible capacity of U-Mg-N-H system increases to 4.9 wt %, 18% higher than that typically obtained from the Mg(NH(2))(2) + 2LiH mixture at 200 degrees C. Furthermore, increasing the Li(3)N:Mg(NH(2))(2) ratio is effective for mitigating the ammonia release from thus-prepared samples. Combined property/structure investigations indicate that the obtained enhancements should be ascribed to the effects of LiNH(2) and LiH that were in situ generated from the excess Li(3)N. LiNH(2) may promote the dehydrogenation reaction via seeding the reaction intermediate. The concurrently generated LiH acts as an effective ammonia trapping agent. These findings highlight the potential of "intermediate seeding" as a strategy to enhance the reversible hydrogen storage properties of metal-N-H systems.
关键词:
complex hydrides;ultrafast reaction;amide;improvement;desorption;linh2;destabilization;mechanism;mixtures;imides
裴增文
,
刘晓鹏
,
黄倬
,
李志念
,
王树茂
,
蒋利军
稀有金属
doi:10.3969/j.issn.0258-7076.2010.04.013
采用等容法研究了机械球磨工艺制备的Li-Mg-N-H材料储氧性能,结果发现,在室温下采用氦气对样品室体积进行标定时,由于Li-Mg-N-H材料对氦气有一定量的物理吸附,造成准确Li-Mg-N-H材料样品体积标定误差,进而造成Li-Mg-N-H储氢材料在503 K下放氢容量随压力的降低而增加异常变化.为准确标定样品体积,通过对Li-Mg-N-H材料室温氮气吸附容量测定,并采用迭代计算方法获得准确的储氢材料样品体积,进而测定Li-Mg-N-H储氢材料503 K下放氢PCT曲线,其表现为放氢容量随压力降低而减小的正常变化规律.Li-Mg-N-H储氢材料503 K,9.6 MPa氢压下的最大储氢容量为4.81%(质量分数),放氢过程表现为单一放氢平台特性.
关键词:
轻质储氢材料
,
Li-Mg-N-H
,
储氢性能
,
等容测试方法
Journal of Alloys and Compounds
Motivated by the ion migration mechanism proposed by David et al. [J. Am. Chem. Soc. 129 (2007) 1594-1601], we mechanically mill the Li3N/Co powder mixture to obtain defective Li3N-type structure with enhanced Li+ mobility. Compared with Li3N the hydrogen storage property of such defective phase is markedly improved, presumably due to the ion-migration-enhancing effect from the incorporation of Co and Fe (from milling utensils). During subsequent cycling, however, this effect cannot persist due to the precipitation of Co-Fe alloy upon hydrogenation. The close correlation between Co-Fe incorporation/precipitation and property variation of Li3N hydrogen storage material provides a preliminary evidence to support the ion migration mechanism. (C) 2007 Elsevier B.V. All rights reserved.
关键词:
Hydrogen absorbing materials;Nitride materials;hydrogen-storage;lithium amide;mechanism;nitride;batteries;mixtures;hydride;imides;linh2;anode
Energy & Environmental Science
The Li-Mg-B-H system that is prepared from 2LiH + MgB(2) or 2LiBH(4) + MgH(2) possesses high hydrogen capacity and relatively favorable thermodynamics, but it is greatly restricted in practical hydrogen storage applications by problematic H-exchange kinetics. In the present study, TiF(3) was mechanically milled with a 2LiH + MgB(2) mixture and examined with respect to its effect on reversible dehydrogenation of the Li-Mg-B-H system. Experimental study showed that TiF(3) is highly effective for promoting the two-step dehydrogenation reaction in the Li-Mg-B-H system. Compared to the neat 2LiH + MgB(2) sample, the 2LiH + MgB(2) + 0.01TiF(3) sample exhibits significantly reduced dehydrogenation temperature and markedly enhanced dehydriding rate at both steps. Furthermore, the catalytic enhancement arising upon adding TiF(3) additive was observed to persist well in the hydrogenation/dehydrogenation cycles. Based on the results of phase analysis and a series of designed experiments, the mechanism underlying the observed property improvement is discussed.
关键词:
complex hydrides;libh4;tif3;kinetics;naalh4
米菁
,
郝雷
,
刘晓鹏
,
杜淼
,
蒋利军
,
王树茂
金属功能材料
doi:10.13228/j.boyuan.issn1005-8192.2015053
基于对Li-Mg N-H体系放氢动力学机理的研究发现,其放氢过程的速率控制步骤是Li+、H+或H-的扩散.在实验中,原位析出的Li3Bi相增加了Li-Mg-N-H体系放氢过程中Li+离子的扩散速率,进而使得该体系在200℃下放氢量(质量分数)从4.37％增加到4.55％,达到90％放氢量的放氢时间从298 min缩短到11 min.
关键词:
储氢材料
,
Li-Mg-N-H Li3Bi
,
放氢
赵中伟
,
刘旭恒
中国有色金属学报
运用同系线性规律对Li-Fe-P-H2O系中缺少的LiFePO4和Li3PO4的△GΘ进行估算.结合已有的热力学数据,运用ψ-pH图的绘制原理,得到25℃时Li-Fe-P-H2O系在不同浓度下的ψ-pH图.结果表明,在水溶液中,LiFePO4具有较大的热力学稳定区域,这对湿法制备LiFePO4很有利.根据所绘制的热力学平衡图,详细讨论了各种LiFePO4软化学制备方法的可行性途径,并就液相法制备LiFePO4可能的技术途径和条件进行分析,为在水溶液中用软化学法制备LiFePO4提供理论依据.
关键词:
Li-Fe-P-H2O系
,
磷酸铁锂
,
热力学
卢洋藩
,
叶志镇
,
曾昱嘉
,
陈兰兰
,
朱丽萍
,
赵炳辉
无机材料学报
doi:10.3724/SP.J.1077.2006.01511
采用Li-N-H共掺技术在玻璃衬底上生长p型ZnO薄膜. XRD结果表明共掺ZnO薄膜具有高度cll轴取向, Hall测试表明薄膜的电阻率为25.2Ω·cm, Hall迁移率为0.5cm2/(V·s), 空穴浓度为4.92×1017/cm3. 此外, p-ZnO薄膜在可见光区域具有90%的高透射率.
关键词:
p-ZnO
,
magnetron sputtering
,
codoping
