材料期刊网

TEXTURES,INTERFACE AND FRACTURE OF A 1D-C/C PREPARED BY CVD

R.Shi , H.J. Li , Z. Yang and M.K. Kang(Dept. of Materials Science and Engineering , Northwestern Polytechnical University , Xi'an 710072 , China Manuscript received 26 August 1996)

金属学报(英文版)

A unidirectional carbon/carbon composite (1D-C/C) of low bulk density with textures of poruns granular and isotropic carbons sharply manifests brittle fracture and does not display high pseudoplasticity as expected. The results of transmisson electron microscopy (TEM) studies show that the strong interface of fiber-matrix should determine its fracture mode.

关键词: :1D-C/C , null , null , null

Enhanced H-storage property in Li-Co-N-H system by promoting ion migration

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

Effect of Li(3)N additive on the hydrogen storage properties of Li-Mg-N-H system

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

H_2气氛保护热处理1J50组织结构与性能的研究

孙建春 , 盛光敏 , 陈登明 , 周安若 , 朱光俊

功能材料

1J50软磁合金的性能主要是通过H_2热处理获得的,在1130℃和H2气氛保护下对冷轧态1J50软磁合金进行了热处理.运用MATS-2010SA软磁测试仪对处理前后1J50软磁合金的磁性能进行了检测,运用金相显微镜、XRD等手段对处理前后1J50软磁合金的组织结构进行了分析.结果表明,通过H_2热处理,1J50软磁合金的矫顽力显著降低,起始磁导率和最大磁导率提高;组织结构发生明显变化,冷轧态1J50软磁合金组织为孪晶奥氏体,平均晶粒尺寸为200μm,处理过后,晶粒显著长大,平均晶粒尺寸为100μm;由于在600℃时采取了快冷,处理后1J50软磁合金中未出现大量FeNi相和FeNi_3相.

关键词: H2热处理 , 1J50 , 组织结构 , 性能

Enhanced Hydrogen Storage Properties of Li-Mg-N-H System Prepared by Reacting Mg(NH(2))(2) with Li(3)N

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

Li-Mg-N-H储氢材料储氢性能测试方法研究

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

Improved hydrogen storage property of Li-Mg-B-H system by milling with titanium trifluoride

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

原位析出Li3Bi对Li-Mg-N-H体系放氢动力学性能的影响

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

Li-Fe-P-H2O系热力学分析

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

Li-N-H共掺法制备 p型 ZnO薄膜

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