Z. Wu
,
C.H. Li
,
P. Qin
,
H.L. Liu and N. Y. Chen(Shanghai Institute of Metallurgy
,
Chinese Academy of Sciences
,
Shanghai 200050
,
China)
金属学报(英文版)
A modified Miedema model using four atomic parameters and pattern recognition or artificial neural network has been used to study the factors that affect the entropy of mixing of liquid binary alloy systems. It has been found that the systems with larger electronegativity difference (△Φ) usuallg have negative △Sxs of mixing, while the systems with larger valence electron density difference(denoted by △n) and small △Φ usually have positive △Sxs of mixing. The artificial neural network-atomic parameter method can be used to predict the △Sxs of binary alloy systems consisting of non-transition elements.
关键词:
entropy of mixing
,
null
,
null
刘奕新
,
杨书全
,
张丹丹
,
黎光旭
,
韦文楼
,
郭进
无机材料学报
doi:10.3724/SP.J.1077.2009.00813
利用机械合金化方法制备了Li-N-H络合氢化物,并研究B、C作为催化剂对其储氢性能的影响.结果表明:LiNH2、Li2NH为Li-N-H络合氢化物的主要储氢相,随B的加入,储氢相的非晶化程度提高.虽然B、C的添加均使储氢量下降,但n(B):n(C)=1:2的混合添加提高了有效储氢量,同时也提高吸放氢动力学性能;B的添加可有效降低可逆吸放氢温度,适当增加球磨时间,有利于提高可逆吸放氢量.
关键词:
Li-N-H络合氢化物
,
储氧性能
,
机械合金化
齐民华
,
沈琪
,
陈小平
,
翁林红
应用化学
doi:10.3969/j.issn.1000-0518.2003.07.004
无水YCl3与1-环戊烷基茚基锂以1/2的摩尔比在THF中反应合成了二(1-环戊烷基茚基)氯化钇(C5H9C9H6)2Y(μ-Cl)2Li(THF)2,产物用元素分析、红外光谱及XRD进行表征. 结果表明,其晶体属于正交晶系,Pna2(1)空间群,a =1.648 2(7) nm,b =1.877 2(8) nm,c =1.131 7(5) nm,V =3.501(3) nm3,Z=4,Dc=1.285 Mg/m3,最终的偏离因子R=0.068 3,Rw=0.114 3.
关键词:
环戊烷基茚基
,
稀土配合物
,
合成
,
晶体结构
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
金春雁
,
王建安
,
徐增莱
,
顾龚平
,
沙莎
,
吴国荣
中国稀土学报
以盾叶薯蓣茎段为外植体,在生根培养基中添加不同浓度的Ce3+,观察其对盾叶薯蓣组培苗生根和抗氧化酶系统及活性氧代谢水平的影响. 结果表明,0.5～20 mg·L-1的Ce3+对盾叶薯蓣组培苗生根有明显的促进作用,可显著提高外植体的生根率、单株发根数、根的鲜重等,5 mg·L-1的Ce3+显示出最强的促进效应,而高浓度的Ce3+呈抑制效应. 培养基中添加合适浓度的Ce3+对组培苗叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)等有显著的调节作用,有效抑制·O2-的生成速率和丙二醛(MDA)的积累,显示出Ce3+对组培苗促进生根的效应与调节活性氧代谢水平的一致性.
关键词:
铈
,
盾叶薯蓣
,
生根效应
,
活性氧代谢
,
稀土
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
张倩倩
,
庄全超
,
徐守冬
,
邱祥云
,
崔永丽
,
史月丽
硅酸盐通报
本文分别以柠檬酸(C6H8O7·H2O)和蔗糖(C12 H22 O11)为碳源,采用溶胶凝胶法合成了Li2 MnSiO4/C材料.X射线衍射(XRD)结果显示合成出的Li2 MnSiO4/C材料均属于正交晶系Pmn21空间群.扫描电子显微镜(SEM)结果表明合成出的Li2 MnSiO4/C1(以C6H8O7·H2O为碳源)材料粒径均在500 nm左右,Li2MnSiO4/C2(以C12 H22O11为碳源)材料粒径在1μn左右.充放电测试结果显示,Li2MnSiO4/C2较Li2 MnSiO4/C1有较高的首次不可逆容量；两种电极材料经几周循环后均具有稳定的循环性能,所制得的Li2 MnSiO4/C1较Li2 MnSiO4/C2具有高的循环容量.
关键词:
锂离子电池
,
Li2 MnSiO4/C
,
碳源
,
包覆
,
电化学性能
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
刘兴亮
,
鲁道荣
,
桂宏亮
金属功能材料
采用溶胶-凝胶法,合成纳米复合材料硅酸亚铁锂(Li2FeSiO4/C).用XRD、TEM和电化学方法,研究了Co2+掺杂对Li2FeSiO4/C的影响.结果表明,掺杂适量的Co2+不会改变Li2FeSiO4的正交晶系结构,可稳定材料结构,改善高倍率充放电性能.室温下,Li2Fe0.97Co0.03SiO4/C以0.1C放电的首次放电比容量为151.8 (mA· h)/g,20次充放电循环后放电比容量为131.2 (mA·h)/g;Li2FeSiO4/C的首次放电比容量为122.0 (mA·h)/g,20次循环后,比容量衰减率为20.3％.交流阻抗测试表明:Li2Fe0.97Co0.03SiO4/C在1.5～4.5V下充放电的可逆性优于Li2FeSiO4/C.
关键词:
溶胶-凝胶法
,
正极材料
,
硅酸亚铁锂
,
掺杂Co2+
,
电化学性能
