A1替代Ni对La2MgNi7.5-xCo1.5Alx

采用X射线衍射、电子探针和电化学测试研究了La2MgNi7.5-xC01.5A1x(x=O.0～0.5)合金的相结构和电化学性能.XRD结果和EPMA观察表明,A1替代改变了合金的物相组成和物相的丰度.LaNi3相消失,αLa2Ni7相丰度的变化表现为先增加(x从O.0～0.1)后减少(x=O.3和O.5),LaNi5相随合金中A1含量x的增加而明显增加.A1替代Ni降低了合金的最大电化学放电容量和活化性能,但明显改善了La2MgNi7.5Co1.5合金的电化学循环稳定性.     

La-Mg-Ni系A5B19超晶格负极材料相结构及电化学性能EI北大核心CSCD

感应熔炼制备La0.8-xCexMg0.2 Ni 3.8(x=0,0.1,0.3,0.5),研究Ce替代部分La对La4MgNi19超晶格负极材料相结构及电化学性能的影响。研究表明,La4MgNi19合金相由LaNi5,(La,Mg)2Ni7,(La,Mg)5Ni19(3R-Ce5Co19)相组成。加入Ce后,(La,Mg)2Ni7相消失,出现2H-Pr 5Co 19结构的(La,Mg)5Ni19相,同时随着Ce替代量的增多,(La,Mg)5Ni19相含量增多,LaNi5相随之减少,Ce加入有利于形成A5B19相,特别是形成2H-Pr5Co19结构。电化学放电容量随着x值的增加呈现先增后减趋势,x=0.1时样品的电化学放电容量380.36 mAh/g最佳。合金电极活化次数、容量保持率和倍率放电性能随着Ce含量增加而增大。H在合金中的扩散速率是影响其倍率放电性能主要因素。     

La0.7-xPrxZr0.1Mg0.2Ni2.75Co0.45Fe0.1Al0.2 (x=0.00,0.05,0.10, 0.15,0.20)合金储氢及电化学性能研究

在Ar气保护下,采用高频感应悬浮炉制备La0.7-xPrxZr0.1Mg0.2Ni2.75Co0.45Fe0.1Al0.2(x=0.00,0.05,0.10,0.15,0.20)合金,研究Pr替代La对合金电极电化学性能的影响。结果显示,所有合金主要由LaNi5和La2Ni7相组成,以Pr替代La后,LaNi5相和La2Ni7合金相的晶胞收缩,导致氢原子在合金电极体内扩散受限,合金电极的动力学性能下降。但由于Pr的抗腐蚀作用,合金电极循环稳定性增加,经过200次充放电循环后容量保持率分别从66.2%(x=0.00)逐渐增加到69.5%(x=0.05)、73.2%(x=0.10)、74.0%(x=0.15)和75.1%(x=0.20)。     

La0.67Mg0.33Ni3.0-xAlx(x=0～0.3)贮氢合金的相结构及电化学性能的研究

研究了Al元素对合金La0．67Mg0．33Ni3．0中Ni的替代对舍金的微观组织结构及电化学性能的影响。X射线衍射(XRD)分析结果表明La0．67Mg0．33Ni3．0合金由PuNi3型(La，Mg)Ni3相和Ce2Ni2型(La，Mg)2Ni7相组成，Al元素加入后，开始出现CaCu5型LaNi5相，随着Al含量的增加，LaNi5相逐渐增多，当x=0．3时，LaNi5相成为合金的主相，合金La0．67Mg0．33Ni3．0中Al的X荧光元素面分布图像表明了Al元素主要进入LaNi5相中，说明Al是一种LaNi5相形成元素；电化学测试表明，随着Al含量的增加，合金的最大放电容量依次下降，4种合金的最大放电量分别为392、324、267和252mAh／g，活化次数变化不大(2～3次即可活化)，循环稳定性先增加后下降。     

Fe部分取代Co对La_(0.7)Zr_(0.1)Mg_(0.2)Ni_(2.75)Co_(0.75-x)Fe_x(x=0,0.05,0.1,0.15,0.2)合金储氢性能的影响

在氩气保护下,采用磁悬浮感应熔炼方法制备La0.7Zr0.1Mg0.2Ni2.75Co0.75-x Fex(x=0,0.05,0.1,0.15,0.2)合金,并研究Fe取代Co对La0.7Zr0.1Mg0.2Ni2.75Co0.75-x Fex(x=0,0.05,0.1,0.15,0.2)合金储氢性能及电化学性能的影响。结果表明:合金主要由LaNi5和La2Ni7相组成,随着Fe含量的增加,LaNi5和La2Ni7相的晶胞体积逐渐增大,且合金中依次出现ZrFe2相(x≥0.05)和La7Ni3相(x≥0.1)。适量的Fe取代Co,不仅能提高La0.7Zr0.1-Mg0.2Ni2.75Co0.75-x Fex(x=0,0.05,0.1,0.15,0.2)合金的储氢容量,降低合金的放氢平台压,改善合金氢化物的稳定性,而且能延长合金电极的循环寿命,提高合金电极的高倍率放电性能。     

Pr替代La对La-Mg-Ni系A_2B_7型电极合金微观结构及循环稳定性的影响

为了改善La-Mg-Ni系A2B7型电极合金的电化学循环稳定性,用Pr部分替代合金中的La,并用熔体快淬技术制备了La0.75-xPrxMg0.25Ni3.2Co0.2Al0.1(x=0、0.1、0.2、0.3、0.4)电极合金。用XRD、SEM、TEM分析了铸态及快淬态合金的微观结构,测试了铸态及快淬态合金的电化学循环稳定性,研究了Pr替代La对合金微观结构及循环稳定性的影响,探讨了合金电极在电化学循环过程中的失效机理。结果表明,铸态及快淬态合金均具有多相结构,包括2个主相(La,Mg)Ni3及LaNi5和一个残余相LaNi2。Pr替代La使(La,Mg)Ni3明显增加而LaNi5减少。电化学测试的结果表明,合金的循环稳定性随Pr替代量的增加而增加。导致合金电极失效的主要原因是电极表面被电解液剧烈腐蚀以及合金电极在电化学循环过程中的粉化。     

La0.7Mg0.3Ni2.65Co0.75-xMn0.1Six储氢电极合金的结构和电化学性能

系统研究了Si部分替代Co对La0.7Mg0.3Ni2.65Co0.75Mn0.1储氢电极合金结构和电化学性能的影响。XRD结果显示,随着Si替代量的增加,合金中(La,Mg)Ni3相的丰度逐渐降低,而LaNi5相的丰度逐渐增加,且含Si合金中出现了La2Ni7相。电化学测试表明,Si部分替代Co降低了合金的放电容量,但显著提高了其循环稳定性,改善了其高倍率放电性能。其中Si替代量x=0.15时合金的综合性能较好,合金最大放电容量323mAh/g,75次循环后的容量保持率约为71.9%,1250mA/g电流放电时的HRD可达55%。     

Mo对A2B7型La-Mg-Ni贮氢电极合金相结构及电化学性能的影响

采用X射线衍射技术(XRD)、电池程控测试仪和电化学工作站等技术手段,研究了少量Mo替换Ni对La0.75-Mg0.25Ni3.5-xMox(x=0~0.5,原子分数/%,下同)贮氢电极合金相结构及电化学性能的影响。结果表明:La0.75Mg0.25-Ni3.5-xMox合金具有多相结构,主相由Gd2Ni7型结构的La2Ni7和CaCu5型结构的LaNi5构成,合金活化性能良好,经过4次充放电过程基本都能达到活化状态。当Mo的加入量达到0.3%时,合金中出现MoNi4,且La2Ni7和LaNi5的点阵参数随之增大;合金的高倍率放电(HRD)性能显著提高,HRDI=900mA/g由82.58%(x=0)增加到86.72%(x=0.5);循环稳定性能(S100)也得到较大改善,呈现先增加后降低的变化趋势,x=0.3时循环稳定性能最好,S100达到76.61%,但合金的最大放电比容量(Cmax)逐渐降低。     

La2-xMgxNi7.0(x=0.4,0.5,0.6,0.7,0.8)贮氢合金结构和电化学性能的研究

用高频感应熔炼的方法制备了La2-xMgxNi7.0(x=0.4,0.5,0.6,0.7,0.8)贮氢电极合金,采用x-ray衍射和XRD粉末衍射全谱拟合分析方法及电化学方法系统研究了随Mg含量的增加,该类合金相结构和电化学性能的变化规律,以及合金在不同退火温度(1123K,1203K,1253K)和不同退火时间(24h,72h,144h)下相结构和微观组织及电化学性能的变化规律.实验结果表明,该类合金由(La,Mg)2Ni7相(Ce2Ni7型结构)、LaNi5(CaCu5型结构)相、(La,Mg)Ni3相(PuNi3型结构)及少量未知相组成.随Mg含量的增加,电极电化学放电容量呈先升高后降低趋势,当x=0.6时达到最大值389.87mAh/g;当Mg含量进一步增加时,电化学放电容量迅速降低,x=0.8时电化学放电容量为188.34mAh/g;随Mg含量的增加,合金组织中(La,Mg)Ni3相和LaNi5相增多.退火处理很大程度上消除了LaNi5相,高温退火有利于(La,Mg)2Ni7相的生成,低温退火有利于(La,Mg)Ni3相生成.退火时间的延长对合金相结构影响不明显,但提高了合金组织均匀性,同时使电化学放电容量降低.不同的退火温度和退火时间对未知相影响不明显.本文研究表明,退火温度对(La,Mg)2Ni7合金相结构有重要影响,Mg含量是影响合金相结构和电化学放电容量的关键.     

镍氢电池负极材料V_2Ti_(0.5)Cr_(0.5)Ni_(1-x)Mo_x(x=0.02~0.08)的结构和电化学性能

为了改善镍氢电池负极材料的循环稳定性能,采用真空感应电弧熔炼炉制备了V_2Ti_(0.5)Cr_(0.5)Ni_(1-x)Mo_x(x=0.02~0.08)合金,分析了不同含量的Mo替代Ni之后对合金电极的组织结构及电化学性能的影响。研究结果表明,电极材料主要由BCC结构的V基固溶体主相和Ti Ni二次相组成,随着合金中Mo替代Ni含量x由0.02增加到0.08,合金电极的放电容量先增加后降低,合金电极的循环稳定性能以及电化学动力学性能先得到改善而后降低,合金电极的综合性能均在x=0.04时达到最好。     

La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的储氢性能研究

针对两种新型稀土型储氢合金La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2的储氢特性进行研究分析。实验表明,相同温度下,La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的PCT曲线基本重合,且都具有优良的吸氢动力学性能;相比之下,后者的滞后系数要小于前者,吸氢量较大,吸氢速率也较快,故其储氢性能较优。300次吸放氢循环实验结果表明,La0.5Y0.5Ni4.8Al0.2合金的吸氢动力学性能虽然略有下降,但抗粉化性能较好。     

Dy0.6Tb0.3Pr0.1(Fe0.95Mn0.05)x取向晶体的结构与磁致伸缩

采用Ｃｚｏｃｈｒａｌｓｋｉ方法生长了Ｄｙ０．６Ｔｂ０．３Ｐｒ０．１（Ｆｅ０．９５Ｍｎ０．０５）ｘ（１．８５≤ｘ≤１．９５）取向合金。所有合金主相为立方Ｌａｖｅｓ相结构,择优取向不完整择优取向的方向与Ｘ的大小有关。研究了沿着这些样品的生长方向的磁致伸缩性能以及磁致伸缩性能与压力之间的关系。     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.     

Plasma surface treatments of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)

The surfaces of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were modified by oxygen and nitrogen plasma treatments. The physical and chemical surface characteristics were evaluated by contact angle tests, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The plasma treatments caused an increase in both contact angle and roughening, altered the surface morphology, inserted polar groups, and, consequently, enhanced the hydrophilicity for both PLLA and PHBV polymers.     

Nanomechanical characterization of one-step combustion-synthesized Al(4)B(2)O(9) and Al(18)B(4)O(33) nanowires

Two kinds of aluminum borate nanowires, Al(4)B(2)O(9) and Al(18)B(4)O(33), were successfully synthesized by a one-step combustion method through control of the Al:B atomic ratio and synthesis temperature. Both nanowires are single crystalline but have distinguishing growth habits. Nanoindentation tests were performed directly on individual nanowires to reveal their mechanical properties. A 70% reduction in elastic modulus was found in Al(18)B(4)O(33) nanowires compared with their bulk counterpart. Al(18)B(4)O(33) nanowires exhibited higher hardness and elastic modulus than Al(4)B(2)O(9) nanowires.     

非晶态半导体 As_(24)Se_(76)、As_(40)Se_(60)和 As_(50)Se_(50)的光量子效率研究

光量子效率是非晶态光电导材料的一个重要参数。本文利用静电放电的方法,探讨和研究了 As—Se 系统非晶态半导体材料的光量子效率与电场和组份的关系,得出的结果与 Onsager 理论描述的相一致。由分析而得到了等剂量组份、富 As 和富 Se 系统光量子效率的变化趋势。     

Natural Passivity of Amorphous Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 Alloys

The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.     

Work Functions of Pd_(83.5)Si_(16.5)and Cu_(70)Ti_(30)Glassy Alloys

The work functions before and aftercrystallization of two glassy alloys,Pd_(83.5)Si_(16.5) andCu_(70)Ti_(30) have been measured by means of the con-tact potential difference method in the secondaryelectron field at room temperature under 10~(-5) Pavacuum.The results show that the work functionsof both glassy alloys are higher than those of thecorresponding crystalline alloys.     

An SANS Study of Decomposition Kinetics in Amorphous Cu_(12.5)Ni_(10)Zr_(41)Ti_(14)Be_(22.5)

Phase decomposition in amorphous Cu12.5Ni10Zr411Ti14Be22.5 alloy as annealed in the super-cooled liquid range was studied by applying small angle neutron scattering (SANS). As annealed between 600 K and 700 K, the alloy was observed to decompose into two new amorphous phases,with the second phase precipitates embedded in the matrix of the first. Long time annealing of the alloy results in crystallization in addition to evolution of the decomposed microstructure.The kinetic diagram of the decomposition and crystallization for this alloy is given. The second phase precipitates have several nanometers in size and occupy a quite low volume fraction. The decomposition of the supercooled liquid in overall temperature range exhibits the features of spinodal reaction.