Al、Ti掺杂对Mg2Ni合金相结构稳定性的影响及其微观机理

采用第一性原理赝势平面波方法,研究元素Al和Ti掺杂对Mg2Ni储氢合金相结构稳定性的影响及其微观机理.结果显示:在掺杂浓度x＝0～0.5范围内,所形成的Mg2Ni型Mg2-xMxNi(M＝Al,Ti)固溶体合金的相结构稳定性随Al掺杂浓度的增大而增强,随Ti掺杂浓度的增大而减弱,且Mg2-xMxNi(M＝Al,Ti)固溶体合金相对于立方结构的Mg3MNi2(M＝Al,Ti)化合物呈现热力学不稳定性,极易分解成由立方结构Mg3MNi2(M＝Al,Ti)和六方结构Mg2Ni组成的复合相,计算结果与实验结果吻合.电子结构分析表明,Al、Ti掺杂Mg2Ni储氢合金的相结构稳定性与体系在低能级区的成键电子数密切相关.     

Mg1.7M0.3(M＝Mg,Ti,Al)Ni贮氢合金结构及性能研究

采用固态烧结法制备了Mg1 7M0 3(M =Mg、Ti、Al)Ni贮氢合金 ,X射线衍射分析结果表明 ,适当提高烧结温度有利于Mg2 Ni相的形成 ;Ti对Mg的取代未引起合金相结构的明显变化 ,而Al取代Mg除有Mg2 Ni相外 ,还有一呈立方晶体结构的新相生成。Ti、Al对Mg的取代 ,不仅提高了Mg2 Ni合金的放电容量 ,同时也提高了合金的循环寿命。     

Mgl．7M0．3（M＝Mg，Ti，Al）Ni贮氢合金结构及性能研究

采用固态烧结法制备了Mg1．7M0．3(M＝Mg、Ti、A1)Ni贮氢合金，X射线衍射分析结果表明，适当提高烧结温度有利于Mg2Ni相的形成；Ti对Mg的取代未引起合金相结构的明显变化，而A1取代Mg除有Mg2Ni相外，还有一呈立方晶体结构的新相生成。Ti、A1对Mg的取代，不仅提高了Mg2Ni合金的放电容量，同时也提高了合金的循环寿命。     

A2B7型La0.75Mg0.25Ni3．5-xAlx（x=0-0．3）合金相结构及电化学性能

采用感应熔炼方法制备了A2B7型La0.75Mg0.25Ni3．5-xAlx（x=0，0．02，0．06 0.1，0．3）四元贮氢合金，系统研究了Al元素部分替代Ni对A2B7型La0.75Mg0.25Ni3．5合金相结构及电化学性能的影响。X射线衍射（XRD）分析表明：La0.75Mg0.25Ni3．5由单一La2Ni7相组成：Al元素加入后，开始出现CaCu5型LaNi5相，当x=0．3时，LaNis相成为合金的主相。Rietveld分析表明：随着Al含量的增加，LaNi5相逐渐增多，Al的加入利于CaCu5型LaNi5相的形成。电化学测试表明：Al替代Ni对A2B7型合金La0.75Mg0.25Ni3．5电极活化性能影响不大：而最大放电容量随Al在La0.75Mg0.25Ni3．5-xAlx，合金中替代量的增加而减小。当放电电流密度为1600mA／g时，合金的倍率放电性能由68.8％（x=0）增加到81．16％（x=0．1）然后减小到65．67％（x=0.3）。此外，La0.75Mg0.25Ni3．5-xAlx合金电极循环稳定性先增加而后下降。x=0．06时合金电极容量保持率最大（S100=85.21．％）。     

Ti合金化Mg2Ni氢化物能量和电子结构的第一性原理研究

采用基于密度泛函理论的第一性原理赝势平面波方法,计算Ti掺杂Mg2Ni储氢合金及其氢化物的能量和电子结构。计算结果表明:在掺杂浓度为0≤x≤0.5的情况下,Ti优先占据Mg(II)位,Ti的掺杂使Mg2Ni合金稳定性降低,且随着掺杂浓度的升高,对稳定性的削弱效果逐渐增强。六方结构的固溶体合金Mg(2-x)TixNi(0≤x≤0.5)相对于立方结构的Mg3TiNi2化合物呈现热力学不稳定性,极易分解为Mg3TiNi2和Mg2Ni组成的复合相。Ti的掺杂使低能级区域的成键电子数减少,削弱了H-Ni的成键作用,提高了Mg2Ni氢化物的解氢能力。     

Mg(2-x)AlxNi的燃烧合成及其电极性能

采用燃烧合成法合成了三元镁基储氢合金Mg2-xAlxNi(x=0.1~0.5),XRD衍射研究表明合成产物中出现了具有Ti2Ni型立方结构的新相,SEM结果显示合金表面存在大量缺陷.Al元素部分替代Mg对Mg2Ni电化学性能影响的研究表明:Mg2-xAlxNi合金的电化学容量和循环寿命明显优于无Al的Mg2Ni,这归因于新相Mg3AlNi2的结构特点及形成的Al2O3保护层.此外,对合成产物的进一步的机械研磨有助于改进合金的活化行为及电极容量,但无助于循环能力的提高.     

La0.67Mg0.33Ni3.0-xAlx（x=0.0-0.35）贮氢合金相结构和电化学性能研究

采用X射线衍射、电子探针和电化学测试研究了La0.67Mg0.33Ni3.0-xAlx（x=0.0-0.35）合金的相结构和电化学性能。XRD结果和EPMA观察表明：La0.67Mg0.33Ni3.0合金由LaNi3相和La2Ni7相组成。然而La0.67Mg0.33Ni3.0-xAlx（x=0．1，0．2，0．35）合金不含LaNi3相。研究结果表明Al替代Ni改变了La0．67Mg0．33Ni3.0合金的相结构，Al替代Ni不利于La0．67Mg0．33Ni3.0合金中LaNi3相的形成。此外，随Al含量的增加，La0.67Mg0.33Ni3.0-xAlx（x=0．1，0．2，0．35）合金的相结构也发生了变化。WDS分析表明：随La0.67Mg0.33Ni3.0-xAlx合金中X的增加，Al在LaNis相中的含量增加，但Al在LaNi2相的含量很少并且几乎不随X变化。电化学性能测试表明：Al替代Ni提高了La0.67Mg0.33Ni3.0合金电极的循环稳定性。但La0.67Mg0.33Ni3.0-xAlx合金电极的放电容量却随Al含量的增加而明显降低。     

钛合金固态相变的归纳与讨论(Ⅱ)——共析和有序化转变

研究了少量Al替代Mg(x=0.1)对La2Mg1-xAlxNi7.5Co1.5贮氢合金电化学循环稳定性的影响.经过充放电循环后,La2Mg1-xAlxNi7.5Co1.5(x=0.0,0.1)合金中的LaNi3相和αLa2Ni7相仍然保持PuNi3型结构和Ce2Ni7型结构,没有发生变化,此外,在这2种合金中出现少量新的物相La(OH)3,Mg(OH)2和Ni.LaNi3相和αLa2Ni7相吸氢形成氢化物后也保持PuNi3型结构和Ce2Ni7型结构.La2MgNi7.5Co1.5吸氢后,LaNi3相和αLa2Ni7相晶胞均呈各向异性膨胀,但LaNi3相的各向异性膨胀程度及晶胞体积膨胀率明显大于αLa2Ni7相.相比La2MgNi7.5Co1.5氢化物,Al替代Mg对La2Mg0.9Al0.1Ni7.5Co1.5氢化物中的αLa2Ni7相吸氢体积膨胀的抑制作用很小,但Al替代Mg使该氢化物中LaNi3相的c轴膨胀率和晶胞体积v的膨胀率均明显降低.电化学吸放氢循环后合金的粒径变化及形貌观察表明,La2Mg0.9A10.1Ni7.5Co1.5合金的抗粉化能力优于La2MgNi7.5Co1.5合金,这是Al替代Mg改善La2MgNi7.5Co1.5合金电极电化学循环稳定性的重要原因.     

Ti53Cu15Ni18.5Al7M3Si3B0.5(M=Zr,Hf, Sc) 高强度块体金属玻璃的制备及其性能

用铜模铸造法制备出直径为2．5mm的多组元Ti53Cu15Ni18．5Al7M3Si3B0．5(M=Zr,Hf,Sc)金属玻璃棒材．DSC和压缩应力应变测试结果表明：合金具有较高的热稳定性和优异的力学性能．其中Tis3Cu15Ni18．5Al7Zr3Si3B0．5合金的Tg,Tx和△Tx分别为703,765和62K;Ti53Cu15Ni18．5Al7Sc3Si3B0．5合金压缩断裂强度高达2325MPa,压缩变形量达1．6％,Young’s模量118GPa。     

过渡金属对Mg2Ni氢化物电子结构和热力学稳定性影响:第一性原理研究

采用基于密度泛函理论(DFT)的平面波赝势(PW-PP)方法,计算并分析了Mg2Ni1-xMx(M=Mn,Fe,Co,Ni,Cu,x=0.25)合金及其氢化物Mg2Ni1-xMxH4的电子结构和热力学稳定性。计算结果表明:Mg2NiH4和Mg2Ni1-xMx的晶胞参数与实验值吻合较好。对Mg2Ni1-xMxH4的电子结构分析发现:氢化物中的Ni—H和M—H键为共价键、Mg—H键为离子键,且Ni—H与M—H键的相互作用强于Mg—H键的。Mn、Fe和Co的部分替代对Ni—H键的相互作用影响较小,而Cu的替代则减弱了Ni—H键的相互作用,这可能是Cu替代后氢化物结构稳定性降低的一个原因。计算了Mg2Ni0.75M0.25H4(M=Mn,Fe,Co,Ni,Cu)的生成焓,分别为-57.7、-61.5、-61.4、63.4和41.6 kJ/mol,与实验值吻合较好。     

X-ray diffraction study of Ba0.985Na0.015Ti0.985Nb0.015O3, Ba0.6Na0.4Ti0.6Nb0.4O3 and Ba0.3Na0.7Ti0.3Nb0.7O3 compositions

The Ba_0.985Na_0.015Ti_0.985Nb_0.015O₃, Ba_0.6Na_0.4Ti_0.6Nb_0.4O₃ and Ba_0.3Na_0.7Ti_0.3Nb_0.7O₃ compositions of the (1 − x) BaTiO₃–xNaNbO₃ (BTNNx) system have been studied by X-ray diffraction and by measurements of dielectric properties. The specimens with composition BTNN (x = 0.015, 0.40 and 0.70) have been refined by the JANA program from X-ray powder diffraction data. Ceramic samples with composition (1 − x) BaTiO₃ + xNaNbO₃ (where x = 0.015, 0.40 and 0.70) were prepared by calcinations from appropriate mixture of BaCO₃, TiO₂, Na₂CO₃ and Nb₂O₅. The calcined powder was sintered at temperature range 1200–1400 °C. As the composition x increased from 0.015 (and 0.70), the ferroelectric ceramics (x = 0.015, FE) with tetragonal phase changed to the ferroelectric relaxors (RFE, x = 0.40). RFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to 180 K) due to a frustration between RFE and FE state. These ceramics present the classical ferroelectric character when 0 ≤ x < 0.075 and 0.55 < x ≤ 1 and relaxor character when 0.075 ≤ x ≤ 0.55.     

Magnetic, electrical and plastic properties of Fe76Nb2Si13B9, Fe75Ag1Nb2Si13B9 and Fe75Cu1Nb2Si13B9 amorphous alloys

Influence of 1 h annealing in vacuum on magnetic, electrical and plastic properties of Fe₇₆Nb₂Si₁₃B₉, Fe₇₅Ag₁Nb₂Si₁₃B₉ and Fe₇₅Cu₁Nb₂Si₁₃B₉ melt spun ribbons were carefully investigated. It was shown that in all cases soft magnetic properties can be significantly enhanced by applying 1-h annealing at characteristic temperatures T_op. This optimization annealing causes that permeability increases more than 15-times and magnetic losses (tangent of loss angle) achieves a minimum in relation to the as quenched state. Using structural examinations (X-ray and HRTEM) it was shown that for the Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy the optimized microstructure corresponds to a nanocrystalline αFe(Si) phase whereas in other alloys to a relaxed amorphous phase free of iron nanograins. As a consequence of this fact the Fe₇₆Nb₂Si₁₃B₉ and Fe₇₅Ag₁Nb₂Si₁₃B₉ alloys show higher plasticity in comparison to the nanocrystalline Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy. Temperatures of the first stage of crystallization, and related diffusion parameters were determined using measurements of resistivity versus temperature with different heating rates.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y₆CoBi₂ [a=0.8312(1) nm, c=0.4144(1) nm], Ho₆CoBi₂ [a=0.8246(2) nm, c=0.4095(1) nm], and Tm₆CoBi₂ [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr₆CoAs₂-type structure (space group P6b2m No. 189). The Zr₆CoAs₂-type structure is a superstructure of the Fe₂P-type structure.     

Zur Kenntnis von RbBa3Ca4Cu3V7O28

Single crystals of RbBa₃Ca₄Cu₃V₇O₂₈ were prepared above the melting point of the reaction mixture. It crystallizes with hexagonal symmetry, space group C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ is the second member of a new structure type of the copper-oxovanadates. Ba²⁺ shows an unusual 12-fold coordination. The two calcium positions are coordinated by trigonal prisms and octahedra respectively. The copper coordination is characterized by a stretched square pyramid. The Cu²⁺ ions are outside the centre nearly in plane of the pyramids.

Zusammenfassung

Einkristalle von RbBa₃Ca₄Cu₃V₇O₂₈ wurden oberhalb des Schmelzpunktes der Reaktionsmischung erhalten. Die Verbindung kristallisiert hexagonal, Raumgruppe C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ ist das zweite Beispiel für einen neuen Strukturtyp der Kupfer-Oxovanadate, mit 12-fach koordinierten Ba²⁺ -Ionen. Die zwei Calciumpositionen sind trigonal prismatisch bzw. oktaedrisch koordiniert. Die Koordination der Cu²⁺-Ionen ist durch eine gestreckte Pyramide charakterisiert. Cu²⁺ ist auβerhalb des Polyederzentrums nahezu in der quadratischen Fläche der Pyramide angeordnet.     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

电弧喷涂制备Fe65Cr20Mo7B3.5SiMn1.5W3涂层

在Q235低碳钢板上利用电弧喷涂工艺进行喷涂,以制得Fe65Cr20Mo7B3.5SiMn1.5W3涂层。喷涂材料为自行配制的丝材,按照35%的填充率将配好的粉填充到U型不锈钢外皮中,经过多道拉拔、挤压工艺制成Φ2mm的粉芯丝材。采用X射线衍射仪、扫描电镜、能谱分析仪、透射电镜对涂层的物相和组织形貌及成分进行了表征;采用差示扫描量热仪、显微硬度仪等设备对涂层的热稳定性及显微硬度进行了检测和分析。试验结果表明:涂层组织形貌呈典型的层状组织结构,由变形良好的带状粒子相互搭接堆积而成。涂层含有50.63%的非晶相,同时含有纳米级的晶相。涂层组织均匀、结构致密、孔隙率低,并且涂层硬度高达1040.5HV0.3,属硬质涂层,具有良好的热稳定性。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.