铝含量对LaNi5—xAlx合金氘化与去氘化动力学函数的影响

测定了LaNi5-xAlx(x=0,0.1,0.2,0.3)的氘化去氘化的动力学参数,评价了铝含量对LaNi5-xAlx合金的氘化与去氘化动力学函数的影响,研究结果表明,铝含量不改变合金的氘化与去氘化的反应级数;反应速率常数随x 的增加而减少,活化能随x的增加而增加,氘化与去氘化反应级数a和b(由固相氘浓度决定）分别为2和1及0．5和1O在α β相域,氘化与去氘化反应的速控步骤分别为氘化物的成核－长大过程和氘化物中氘的扩散过程。     

LaNi5-xAlx合金吸放氢过程的滞后现象

测定了LaNi5-xAlx(x=0, 0.1, 0.2, 0.3)合金在吸放氢过程中P-C等温线的坪台压力及热力学参数.结果表明,坪台压力与热力学参数焓变ΔH,熵变ΔS随合金中Al含量的增加而降低,吸氢及放氢过程中的坪台压力存在一定的差异,即滞后现象(用滞后系数Hf表示).Hf随温度的升高而减弱,随合金中Al含量的增加而降低.滞后现象与合金在吸放氢过程中的应力释放有关.     

Ti-Hf合金的结构和吸氘热力学性质

采用磁悬浮法制备了4种TiHfx,(x=0.13,0.26,0.52,1.03)二元合金。利用X射线衍射技术对纯钛、纯铪和4种成分Ti-Hf二元合金吸氘前后的物相结构、晶胞参数和吸氘特性进行了研究。Ti-Hf合金吸氘前均为六方密堆结构,饱和吸氘后形成较单一的面心四方ε相氘化物。随Hf含量增加,Ti-Hf合金及其ε相氘化物的晶胞参数均呈增大趋势。压强-组成等温线显示,Hf含量增加将导致氘化物室温平衡压升高,Ti-Hf合金热力学性质趋近于H-Hf体系,Hf对Ti-Hf合金氘化物热力学性质起主导作用。Hf掺杂显著降低了Ti吸氘的体膨胀,从而有望缓解由于体胀导致的氢脆现象。     

硼对La17Fe76B7型储氢合金结构和电化学性能的影响

采用中频感应熔炼-快淬方法制备了La17Fe3Mn5Al2Ni73-xBx(x=0,1,3,5)储氢合金。结构分析表明,不含B的合金为双相结构,主相为LaNi5相,第二相为La2Ni7相,含B合金均由LaNi5相、La2Ni7相和La3Ni13B2相组成,且随着B含量的增加,LaNi5相和La2Ni7相减少,La3Ni13B2相逐渐增加。电化学测试表明,随着B含量的增加,合金的活化性能、最大放电容量不同程度下降,而循环稳定性有所改善。合金电极的倍率放电能力(HRD)随着B含量的增加呈先增大后减小的趋势,表明适量的B有利于提高合金的高倍率放电性能。合金电极的交换电流密度(I0)随着B含量的增加先增大后减小,而氢在合金中的扩散系数(D)则逐渐增大,表明合金的高倍率放电性能主要取决于合金表面的电荷转移能力。     

储氢合金La0.7-xCexMg0.3Ni2.4Co0.6(x=0～0.4)电化学性能研究

研究了以Ce部分取代La对AB3型储氢合金La0.7-xCexMg0.3Ni2.4Co0.6(x=0~0.4)结构和电化学性能的影响.实验表明,该系列合金主要包含LaNi3相和LaNi5相.随着Ce含量的增加,合金电极的最大放电容量逐渐降低,但循环稳定性得到了明显改善.     

金属镱高压吸氘性能研究

大部分稀土金属与氢反应 ,都能很容易地生成三氢化物。但镱和铕却是例外 ,镱在氘压力小于 1 .0 3× 1 0 5Ｐａ时只生成二氘化物。文献报道金属镱在氢压力约为 2 .0ＭＰａ时生成ＹｂＨ2 .58,2 0 0～30 0℃等温线平台区从约ＹｂＨ2 扩展到接近ＹｂＨ2 .5,表明有两种不同的氢化物物相存在。基于ｖａｎ’ｔＨｏｆｆ计算得到ＹｂＨ2 .5(至二氢化物 )离解热约为 1 3.8ｋＪ/ｍｏｌＨ2 。对于在压力大于 0 .1ＭＰａ条件下获得的高含氢量氢化镱 ,Ｈａｒｄｃａｓｔｌｅ报道有一个ａ为 5 .1 92 的ｆｃｃ相与低氢含量的氢化物相共存[1 ] ,两个物相的存…     

La0.7-xNdxMg0.3Ni3.4Al0.1(x=0～0.4)储氢合金的相结构及电化学性能

采用真空烧结方式制备了AB3.5型La0.7-xNdxMg0.3Ni3.4Al0.1(x=0,0.1,0.2,0.3和0.4)储氢合金.XRD分析表明,所有合金均由LaNi5,La2Ni7和LaNi3三相组成.当Nd含量增加时,合金中的LaNi5和La2Ni7相含量有不同程度的增加,而LaNi3相相应减少.电化学性能测试表明,添加适量的Nd能改善合金电极的循环稳定性,其中La0.6Nd0.1Mg0.3Ni3.4Al0.1合金具有相对较好的综合性能,其最大放电容量达到322.4 mAh·g-1,循环50周的容量保持率(S50)达到89.98%.     

钪元素对AB2型合金Zr1-xScxMn0.6V0.2Ni1.2Co0.1（x=0～1）储氢和电化学性能的影响

用真空电弧熔炼方法制备了Zr1-xScxMn0.6V0.2Ni1.2Co0.1(x=0～1)AB2型储氢合金,研究了Sc元素替代Zr对合金的微观组织结构、气态储氢及电化学性能的影响。研究结果表明,Zr1-xScxMn0.6V0.2Ni1.2Co0.1合金主要是由FCC型C15相、CsCl型结构的(ScZr)Ni相和少量的Ni10Zr7相组成,随Sc含量的增加,C15相丰度逐渐减小,(ScZr)Ni相丰度逐渐增加,当x=0.2时Ni10Zr7相基本消失;Sc元素对合金的首次气态吸氢动力学行为影响较大,随Sc含量的增加,合金吸氢动力学性能逐渐变缓,但吸氢容量逐渐提高,直至达x=1.0时的最大吸氢量1.87%;Sc元素对合金吸氢PCT曲线平衡氢压的影响规律不明显,随Sc含量增加,合金氢化物的形成焓ΔH从-26.66 kJ.mol-1逐渐减小到-8.14 kJ.mol-1。Sc元素的加入可明显改善合金电极的活化性能,提高放电容量,随Sc含量的增加,合金电极最大放电容量从x=0时的350.3 mAh.g-1增加到x=1时的429.8 mAh.g-1,呈先减小后增大的趋势,但电极容量的保持率S100随Sc含量增加而快速下降。     

低钴LaNi4.5Co0.4-xAl0.1+x储氢合金的相结构和电极性能

采用XRD,SEM等材料分析方法及恒电流充放电、线性极化等电化学测试技术研究了低钴LaNi4.5Co0.4-xAl0.1+x(x=0.00～0.30)储氢合金的电极性能。XRD分析表明:合金均为单一CaCu5型六方结构的LaNi5相结构,随着合金中Al含量的增加,其晶胞参数a和c及晶胞体积都显著增加。301 K时模拟电池测试结果表明:x=0.00时,合金电极具有最佳自放电性能;x=0.15时,合金电极的循环稳定性能最好,其高倍率放电性能达到70.21%(放电电流密度为1800 mA.g-1)。当0.10≤x≤0.15时,Al替代Co能改善AB5型低钴储氢合金的循环稳定性能和高倍率放电性能。     

镁含量对RE-Mg-Ni系A2B7型储氢合金结构与性能的影响

采用感应熔炼方法制备了La0.8-xGd0.2MgxNi3.1Co0.3Al0.1(x=0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4)储氢合金, 并在氩气气氛和1173 K下进行退火处理. 合金相结构分析结果表明, 镁含量(x)较低时合金以Ce2Ni7型为主相结构, A2B7型相丰度(Ce2Ni7+Gd2Co7)达到98.8%; 镁含量较高时合金相由A2B7型、 CaCu5型和PuNi3型物相构成, 随着镁含量的增加, PuNi3型和CaCu5型相组成逐渐增多, 其晶胞参数随Mg含量的增加而减小, 同时合金的吸氢平台也随之升高. 电化学测试结果表明, 随着合金中Mg含量增加, 合金电极的最大放电容量和循环稳定性均呈先增大后减小的规律, 其中x=0.15时合金电极具有最高的电化学放电容量(393 mA·h/g)和最佳的循环寿命(S100=92.82%). 合金电极的高倍率放电性能(HRD)随Mg含量的增加先减小再增大然后又减小, 适量的Mg元素改善了合金电极的动力学性能.     

LaNi4.7Al0.3Dx去氘化热、质传输二维模型研究

建立了LaNi4.7Al0.3Dx去氚化过程中热，质传输的二维数学模型。该模型考虑了气相和固相之间存在的温差以及氚化的密度和比热的变化。计算了金属氚化的在去氚化过程中气－固相温差，组分和密度的分布，以及热导率和加热流体温度对气－固相温差的影响，并考察了模型的适用性。计算结果表明：热导率及加热流体温度对气－固相温差影响显著，最大温差随热导率的增加而减小，随加热流体温度的升高而增大；金属氚化物中组分和密度的分布与气－固相温差有关；根据数学模型获得的反应分数与实验值具有很好的一致性。     

Probing Spatial Distribution of Alignment by Deuterium NMR Imaging

Deuterium NMR imaging was used to evaluate the spatial distribution of the degree of alignment in different types of alignment media by monitoring the deuterium quadrupolar splitting using spatially resolved NMR techniques in conventional liquid state NMR instruments. These images allow the unambiguous distinction of magnetic field and alignment inhomogeneities present in partially aligned samples, revealing the underlying reasons for linebroadening within an alignment medium that cannot be explained by the sole analysis of 1D ²H NMR spectra. For example, alignment inhomogeneities due to broken gels or the presence of concentration gradients in liquid crystalline solutions are clearly detected by the imaging methods proposed in this work.     

α-proton deuterium exchange of five-coordinate bicycloazastannoxides catalyzed by Et3N

The live-coordinate bicycloawstannowxides (1–6) in the presence of Et₃N has been investigated by ♪1H NMR spectrograph. It has been found that the deuterium exrhange of αCH of five-coordinate bicycloazastannoxides with CD₃0D takes place, which is catalyzed by Et₃N. In the presrnce of Et₃ N(2 pL), the apparent rate constants (koba.) for the deuterium cxchangc in CD₃OD) is determined by ♪1H NMR method, wd the value of k_Oba is in the range of (2.05-10.8) ×10-⁴ s^-1. Thr effect of the substitutes on the rates and the kinetic mechanism are discussed.     

α-proton deuterium exchange of five-coordinate bicycloazastannoxides catalyzed by Et_3N

The five-coordinate bicycloazastannoxides (1—6) in the presence of Et_3N has been investigated by~1H NMR spectrograph. It has been found that the deuterium exchange of αCH of five-coordinate bicycloazastannoxides with CD_3OD takes place, which is catalyzed by Et_3N. In the presence of Et_3N (2μL), the apparent rate constants (k_(obs)) for the deuterium exchange in CD_3OD is determined by~1H NMR method, and the value of k_(obs) is in the range of (2.05--10.8)×10~(-4) s~(-1). The effect of the substitutes on the rates and the kinetic mechanism are discussed.     

氘代阿戈美拉汀的合成

以苯酚为原料,氘代碘甲烷与氘代醋酸酐为氘代试剂.经过氘代甲基化、傅克酰基化、克脑文盖尔缩合、芳构化、还原及氘代乙酰化反应得到氘代标记的阿戈美拉汀(1).该合成路线简洁,原料易得、反应条件易于控制,总收率为15.2%,化学纯度为99.97%,氘代丰度大于98%.目标化合物结构经质谱、核磁共振等表征确定可用于其药代动力学研究.     

La2—xSrxCuO4和La2—xNdxCuO4＋y的键共价性计算

使用复杂晶体化学键理论计算了Ｌａ２－ｘＳｒｘＣｕＯ４和Ｌａ２－ｘＮｄｘＣｕＯ４＋ｙ中各键的健共价性,讨论了键性随着掺杂的变化规律,研究表明,对于２１４结构,没有发现明显的化学键性与超导温度的关系,因此２１４结构中有关超导现象产生的机理还有待于进一步研究。     

Nmr Spectroscopic Determination of Water In Deuterium Oxide/Water Mixtures

Abstract

Deuterium oxide was determined in synthetic mixtures of 70–100 % D₂O and 90–100 % D₂O by NMR spectroscopy with a Varian A-60 NMR spectrometer using peak heights and areas. The standard deviation for the best results was 0.4 % D₂O.     

An efficient and scalable process to produce morpholine-d8

Incorporation of isotopes has long been used as a research tool to label carbons and elucidate biochemical pathways. More recently, H→D exchange has led to analogs of therapeutic agents with improved metabolic stability and properties. Such compounds also have the potential for an improved drug/drug interaction profile and may even avoid the formation of toxic metabolites. Hence, a clear need for an efficient access to deuterated intermediates on large scale has emerged. In the context of an ongoing drug discovery program, we required large quantities of morpholine-d₈. We herein report the successful optimization of a one-pot process allowing a near complete exchange of all methylene hydrogens in morpholine to deuterium atoms using D₂O as the sole source of deuterium and Raney Nickel as catalyst. This facile and safe protocol will be used to scale up the synthesis of morpholine-d₈ in due course.     

Development of a microwave-enhanced isotopic labelling procedure based on the Eschweiler–Clarke methylation reaction

A number of primary and secondary amines have been rapidly methylated under microwave-enhanced conditions using formic acid-formaldehyde mixtures, providing a route to ²H(D)-containing compounds and the potential for ³H(T), ¹¹C, ¹³C and ¹⁴C labelling.     

Evidence for site‐specific intra‐ionic hydrogen/deuterium exchange in the low‐energy collision‐induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation

The experimental investigation of site‐specific intra‐ionic hydrogen/deuterium (H/D) exchange in the low‐energy collision‐induced dissociation (CID) product ion spectra of protonated small molecules generated by electrospray ionisation (ESI) is presented. The observation of intra‐ionic H/D exchange in such ions under low‐energy CID conditions has hitherto been rarely reported. The data suggest that the intra‐ionic H/D exchange takes place in a site‐specific manner between the ionising deuteron, localised at either a tertiary amine or a tertiary amine‐N‐oxide, and a γ‐hydrogen relative to the nitrogen atom. Nuclear magnetic resonance (NMR) spectroscopy measurements showed that no H/D exchange takes place in solution, indicating that the reaction occurs in the gas phase. The compounds analysed in this study suggested that electron‐withdrawing groups bonded to the carbon atom bearing the γ‐hydrogen can preclude exchange. The effect of the electron‐withdrawing group appears dependent upon its electronegativity, with lower χ value groups still allowing exchange to take place. However, the limited dataset available in this study prevented robust conclusions being drawn regarding the effect of the electron‐withdrawing group. The observation of site‐specific intra‐ionic H/D exchange has application in the area of structural elucidation, where it could be used to introduce an isotopic label into the carbon skeleton of a molecule containing specific structural features. This could increase the throughput, and minimise the cost, of such studies due to the obviation of the need to produce a deuterium‐labelled analogue by synthetic means. Copyright © 2010 John Wiley & Sons, Ltd.