(Ce0.9Nd0.1)1-xMoxO2-δ(0.00≤x≤0.10)的合成、表征与电性能

采用溶胶-凝胶法合成(Ce0.9Nd0.1)1-xMoxO2-δ(x=0.00、0.02、0.05、0.10)氧化物,通过X射线衍射(XRD)、场发射扫描电镜(FESEM)等手段对氧化物进行结构表征,交流阻抗谱测试电性能.结果表明:所有样品均为单一萤石立方结构;少量MoO3的加入提高了材料的致密性,降低了材料的总电阻、晶界电阻和晶界电阻在总电阻中所占比例,提高了材料的电导率.1200 ℃烧结样品24 h,测试温度700℃时,(Ce0.9Nd0.1)1-xMoxO2-δ(x=O.00)总电导率和晶界电导率分别为0.05和O.19 S·m-1,掺Mo材料(Ce0.9Nd0.1)1-xMoxO2(x=0.02)的总电导率和晶界电导率分别为2.42和3.96 S·m-1.     

固体电解质Ce_(0.9)Er_(0.1-x)Pr_xO_(1.95+δ)的微观结构及电性能

采用柠檬酸溶胶-凝胶法制备了固体电解质Ce0.9Er0.1-xPrxO1.95+δ(x=0.02~0.08),利用X射线粉末衍射(XRD)、原子力显微镜(AFM)、拉曼光谱(Raman)、X射线光电子能谱(XPS)和交流阻抗谱研究了样品的微观结构和电性能.XRD结果表明,800℃煅烧的所有样品均形成了单相立方萤石结构;Raman光谱结果表明,Ce0.9Er0.05Pr0.05O1.95+δ具有氧缺位的立方萤石结构;XPS分析表明,Ce0.9Er0.05Pr0.05O1.95+δ存在氧缺位,Pr3+离子和Pr4+离子共存;AFM观测结果表明,1300℃下烧结的样品比1400℃下烧结的样品致密;交流阻抗谱结果表明,Pr掺杂量x=0.05时,Ce0.9Er0.05Pr0.05O1.95+δ的电导率最高(σ600℃=1.34×10-2S/cm,Ea=0.90 e V),比未掺杂Pr的Ce0.9Er0.1O1.95(σ600℃=8.81×10-3S/cm,Ea=0.92 e V)提高了52%,说明在Ce0.9Er0.1O1.95中适量掺杂Pr可提高材料的电导率,降低活化能.     

MgO掺杂Ce_(0.9)Sm_(0.1)O_(2-δ)固体电解质的结构和电性能

采用溶胶-凝胶法合成SiO2含量为5.0×10-4(w)的Ce0.9Sm0.1O2-δ(SDC)粉体(SDCSi),并将0-3.0%(x)MgO分别加入到SDCSi陶瓷粉体中,用X射线衍射(XRD)和场发射扫描电子显微镜(FE-SEM)对材料进行表征,用交流阻抗谱(AC)测试材料的电性能.结果表明:MgO掺杂能使SDCSi的烧结温度降低100-200℃,提高陶瓷材料的致密度;清除或降低陶瓷材料晶界处SiO2杂质的有害影响,显著提高晶粒/晶界电导率和总电率;MgO掺杂到SDCSi具有烧结助剂和晶界杂质清除剂的双重作用.     

La2(Mo1-xVx)2O9-α的制备及其导电性

采用固相法合成了系列陶瓷样品La₂(Mo_1-xV_x)₂O_9-α (x=0.02, 0.04, 0.06, 0.08). 粉末X射线衍射(XRD)结果表明样品具有单一立方相La₂Mo₂O₉结构. 采用气体浓差电池、电化学阻抗等电化学方法研究了陶瓷样品在823-1123 K下的导电特性. 系列陶瓷样品已完全抑制La₂Mo₂O₉母体在853 K附近的相变; 各样品在干燥及湿润氧气气氛中几乎为纯氧离子导体, 质子导电性可忽略不计; 氧离子电导率σ随掺杂离子浓度的变化为σ(x=0.02)<σ(x=0.08)<σ(x=0.06)<σ(x=0.04), 这与晶胞自由体积大小的次序完全一致, x=0.04样品具有最高的氧离子电导率0.051 S·cm^-1; 氧分压与电导率的关系表明, 在高氧分压气氛中样品是纯的氧离子导体, 在低氧分压气氛中是氧离子与电子的混合导体.     

掺杂MoO_3对Ce_(0.8)Nd_(0.2)O_(1.9)固体电解质结构与电性能的影响

采用溶胶凝胶方法将过渡金属氧化物MoO3加入到Ce0.8Nd0.2O1.9体系中,讨论MoO3的掺杂对微观结构及电性能的影响。通过X-射线衍射(XRD)、场发射扫描电镜(FE-SEM)等手段对氧化物进行结构表征,交流阻抗谱测试电性能。结果表明:烧结过程中MoO3在晶粒边缘形成液相,增加了晶粒间浸润性,晶粒间位置重排并接触,晶界滑移加快,促使材料致密化,晶界体积分数降低;总电导率和晶界电导率因晶界电阻减少而提高。600℃时,NDC的σt和σgb分别为6.42×10-3和2.03×10-2S·cm-1,加入MoO3后材料的σt提高约1.5倍,σgb提高约4倍。MoO3是NDC体系理想的烧结助剂。     

Ba0.9La0.1Ce0.9Nd0.1O3-α陶瓷的离子导电性

用高温固相反应法制备了Ba0.9La0.1Ce0.9Nd0.1O3-α质子导电性陶瓷,粉末X-射线衍射(XRD)分析表明,该陶瓷为单一钙钛矿型斜方晶结构。在500~900℃温度范围内,分别用气体浓差电池方法和交流阻抗谱技术研究了材料在不同气体气氛中的离子导电性,并与Ba0.9Ca0.1Ce0.9Nd0.1O3-α材料的离子导电性进行了比较。结果表明,在500~900℃温度范围内、湿润氢气中,Ba0.9La0.1Ce0.9Nd0.1O3-α材料的质子迁移数为1,是一个纯的质子导体。在干燥空气中,该材料是一个氧离子和电子空穴的混合导体,氧离子迁移数为0.295~0.081,氧离子电导率高于Ba0.9Ca0.1Ce0.9Nd0.1O3-α。在湿润空气中,该材料是一个质子、氧离子和电子空穴的混合导体,质子迁移数为0.151~0.009,氧离子迁移数为0.300~0.107,质子电导率低于Ba0.9Ca0.1Ce0.9Nd0.1O3-α材料。在氢-空气燃料电池条件下,Ba0.9La0.1Ce0.9Nd0.1O3-α材料是一个质子、氧离子和电子的混合导体,离子迁移数为0.964~0.853,离子电导率与Ba0.9Ca0.1Ce0.9Nd0.1O3-α材料相近。     

La0.5>RE0.3Sr0.2FeO3－δ (RE = Nd、Ce、Sm)体系双稀土阴极材料的制备与电性能

采用甘氨酸-硝酸盐法(GNP)合成了La0.5RE0.3Sr0.2FeO3－δ(RE=Nd、Ce、Sm)系列复合氧化物粉体. 用X射线衍射(XRD)和TG-DSC分析了样品钙钛矿物相的形成过程, 用Archimedes排水法测量体积密度并计算烧结样品的相对密度, 用四端子技术测量电导率. 结果显示, 掺Nd的样品1200 ℃烧结2 h成为单一立方钙钛矿结构, 掺Ce样品有明显的CeO2立方相析出, 掺Sm样品主相为钙钛矿结构伴有微弱的杂峰. 1250 ℃烧结2 h的La0.5Nd0.3Sr0.2FeO3－δ在600 ℃时电导率高达100 S•cm-1以上, 明显高于La0.5Ce0.3Sr0.2FeO3－δ及La0.5Sm0.3Sr0.2FeO3－δ样品的电导率, 预示着La0.5Nd0.3Sr0.2FeO3－δ可能是一种良好的中温固体氧化物燃料电池(SOFC)阴极材料.     

中温固体氧化物燃料电池阴极材料Nd2-xSrxCuO4的制备与性能研究

采用固相法合成了类钙钛矿结构的中温固体氧化物燃料电池(IT-SOFC)阴极材料Nd2-xSrxCuO4(简称NSC,x=0.0～0.1).通过XRD和SEM对材料进行了表征.结果表明该阴极材料与电解质Ce0.9Gd0.1O1.9(CGO)在1 000℃烧结4 h后不发生化学反应,具有良好的化学相容性;且烧结后二者之间能形成良好的接触界面.利用交流阻抗谱研究了电极的性能.发现随着Sr掺杂量的增加,极化电阻逐渐减小,其中Nd1.93Sr0.07CuO4在空气中的极化电阻最小,750℃时仅为0.14 Ω·cm2.700℃时,电极反应的速率控制步骤为电极上发生的电荷转移过程.     

铝掺杂对铜铈复合氧化物催化一氧化碳氧化性能的影响

以金属硝酸盐为原料、碳酸钠为沉淀剂,采用共沉淀法制备了一系列Cu0.1Ce0.9-xAlxOy复合氧化物催化剂,并用低温氮气吸附/脱附、X-射线衍射(XRD)和氢-程序升温还原(H2-TPR)等对样品进行了表征,利用微反-色谱评价装置考察了催化剂对CO低温氧化反应的活性,研究了Al含量(x=0～0.3)和催化剂焙烧温度(350、500和650℃)对Cu0.1Ce0.9-xAxOy催化活性的影响。结果表明,随着催化剂中Al含量(x)的增加,Cu0.1Ce0.9-xAlxOy的催化活性先提高,至x=0.1时达到最大,之后又逐渐降低;当催化剂的焙烧温度为500℃时,Cu0.1Ce0.8Al0.1Oy的催化活性最大。Cu0.1Ce0.9-xAlxOy的催化活性与其CuO的还原性之间有较好的对应关系。     

Ba0.9Sr0.1Ce0.9Nd0.1O3-α陶瓷的离子导电性

用高温固相反应法制备了质子导电性陶瓷Ba0.9Sr0.1Ce0.9Nd0.1O3-α。用粉末X-射线衍射(XRD)和扫描电子显微镜(SEM)对该陶瓷材料进行了表征;用交流阻抗谱技术和气体浓差电池方法研究了材料在500~900℃温度范围内、不同气体气氛中的离子导电性,并与BaCe0.9Nd0.1O3-α和Ba0.9Ca0.1Ce0.9Nd0.1O3-α材料的导电性进行了比较。结果表明,该陶瓷材料为单一钙钛矿型BaCeO3斜方晶结构,具有良好的致密性,在高温下、CO2或水蒸气气氛中具有较高的稳定性。在湿润氢气气氛中、500~800℃温度范围内,材料的质子迁移数为1,是一个纯的质子导体;在900℃下,质子迁移数为0.964,是一个质子与电子的混合导体,质子迁移数高于BaCe0.9Nd0.1O3-α(在700~900℃温度范围内,质子迁移数为0.95)。在湿润空气气氛中,材料的质子迁移数为0.019~0.032,氧离子迁移数为0.093~0.209,是一个质子、氧离子和电子空穴的混合导体,总电导率高于Ba0.9Ca0.1Ce0.9Nd0.1O3-α。在氢-空气燃料电池条件下,材料的离子迁移数为0.957~0.903,是一个质子、氧离子和电子的混合导体,离子电导率高于Ba0.9Ca0.1Ce0.9Nd0.1O3-α。     

镧系稀土四元配合物Ln(NO_3)_2(phen)_2(CH_3COCHCOCH_3)的合成及晶体结构表征

以乙酰丙酮(Hacac)、邻菲咯啉(phen)、硝酸根为配体,8-羟基喹啉为酸度调节剂合成出一个系列的镧系轻稀土四元配合物Ln(NO3)2(phen)2(CH3COCHCOCH3)(Ln=La,Ce,Pr,Nd,Sm)。配合物的结构与性质由元素分析,IR,1HNMR和TGA等表征。单晶Ce(NO3)2(phen)2(CH3COCHCOCH3)·H2O结构经由X射线衍射仪分析表明,晶体属单斜晶系,空间群P21/n,晶胞参数为a=1.11017(8)nm,b=0.98401(7)nm,c=1.34453(10)nm,β=102.0530(10)°,V=1.43641(18)nm3,Dc=1.715g·cm-3,Z=2,F(000)=742。配合物呈单核结构,中心离子Ce髥配位数为10。     

Ce0.8Gd0.2-xPrxO1.9固溶体的合成与表征

利用X射线衍射(XRD)、拉曼光谱(Raman)、X射线光电子能谱(XPS)和交流阻抗谱对溶胶-凝胶法制备的稀土双掺杂固溶体Ce0.8Cd0.2-xPrxO1.9(x=0,0.02,0.10)的结构和导电性进行了研究.XRD结果表明,经800℃焙烧所得样品都形成了单相立方萤石结构,平均晶粒尺寸在23～30 nm之间;X...     

Structure, Microstructure, and Mixed Conduction of [(ZrO2)0.92(Y2O3)0.08]0.9(TiO2)0.1

[(ZrO₂)_0.92(Y₂O₃)_0.08]_0.9(TiO₂)_0.1 (titania-doped yttria stabilized circonia, 10TiYSZ) samples were prepared by solid state reaction from mixtures of 8 mol% yttria-doped ZrO₂ (YSZ) and TiO₂ and characterized in terms of structure, microstructure, and electrical properties. [(ZrO₂)_0.97(Y₂O₃)_0.03]_0.9(TiO₂)_0.1 (titania-doped tetragonal zirconia polycrystalline, 10TiTZP) was also prepared for comparison in some specific studies. Ionic transport properties were measured by impedance spectroscopy in air as a function of temperature. DC techniques including electromotive force (EMF) and Ion Blocking measurements (IB) were carried out in order to determine the electronic contribution to the total conductivity. The addition of titania to YSZ induces the tetragonal zirconia phase formation, thus [(ZrO₂)_0.92(Y₂O₃)_0.08]_0.9(TiO₂)_0.1 is a composite material and is constituted by two solid solutions, titania-doped yttria-stabilized zirconia (67.7 mole fraction) and titania-doped tetragonal zirconia (32.3 mole fraction). A decrease in bulk ionic conductivity, of one order of magnitude, when TiO₂ is added to YSZ is observed in the whole temperature range. Furthermore, in the bulk conductivity vs the reciprocal of the temperature plot, a bending (from 550°C to higher temperatures) toward higher activation energies was detected. The bending could indicate the existence mainly of Ti⁴⁺-Vö associated pairs with an association energy of 0.43±0.02 eV. It could mean that Ti-O bonds become stronger and shorter and could produce the formation of microdomains of a ZrTiO₄-like structure. The addition of titanium is effective in increasing the electronic conductivity under reducing conditions. Conductivity as a function of Po₂ and IB results cannot be related to the formation of small polarons during the reduction process. Furthermore, according to the calculations based on the small polaron theory, inconsistent values for the radius of a small polaron (r_p) are obtained in both 10TiYSZ and 10TiTZP. However, large polarons can explain the transport properties in these materials under reducing conditions in agreement with the experimental data.     

Conductivities of the Ternary Systems Y(NO3)3+La(NO3)3+H2O, La(NO3)3+Ce(NO3)3+H2O, La(NO3)3+Nd(NO3)3+H2O and Their Binary Subsystems at Different Temperatures

Electrical conductivities were measured for the ternary systems Y(NO₃)₃+La(NO₃)₃+H₂O, La(NO₃)₃+Ce(NO₃)₃+H₂O, La(NO₃)₃+Nd(NO₃)₃+H₂O, and their binary subsystems Y(NO₃)₃+H₂O, La(NO₃)₃+H₂O, Ce(NO₃)₃+H₂O, and Nd(NO₃)₃+H₂O at (293.15, 298.15 and 308.15) K. The measured conductivities were used to test the generalized Young’s rule and the semi-ideal solution theory. The comparison results show that the generalized Young’s rule and the semi-ideal solution theory can yield good predictions for the conductivities of the ternary electrolyte solutions, implying that the conductivities of aqueous solutions of (1:3 + 1:3) electrolyte mixtures can be well predicted from those of their constituent binary solutions by the simple equations.     

The crystal structure of a complex cerium(III) molybdate; Ce6(MoO4)8(Mo2O7)

Ce₆Mo₁₀O₃₉ crystallizes in the triclinic system with unit-cell dimensions (from single-crystal data) a = 10.148(5), Å, b = 18.764(6), Å, c = 9.566(5), Å, α = 103.12(7)°, β = 78.07(7)°, γ = 107.69(7)°, and space group $\text{P}\text{1}\text{, z = 2}$. The structure was solved using direct methods with 3113 countermeasured reflections (MoKα radiation), and refined using Fourier and least-squares techniques to a conventional R of 0.039 (ωR = 0.047). Ce₆Mo₁₀O₃₉ has a structure that consists of isolated MoO₄ tetrahedra together with one corner-shared pair of tetrahedra, linked to irregular eight-coordinate Ce(III) polyhedra. The average MoO distance of 1.77 Å, and average CeO distance of 2.52 Å are in good agreement with previously reported values.     

氢键构筑的新颖微孔配位聚合物[Co2(Hisor)2·(4,4′-bpy)2(H2O)2]·4,4′-bpy的合成与结构

A novel microporous coordination polymer [Co2(Hisor)2(4,4′-bpy)2(H2O)2]·4,4′-bpy was synthesized by hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analysis and IR spectrum. The crystal belongs to the monoclinic system and space group is P2/n with a=1.040 6(3) nm, b=1.138 8(4) nm, c=1.854 7(6) nm, β=102.991(6)°, V= 2.141 6(12) nm3, Z=2, Dc=1.443 Mg/m3, Mr=930.62, μ=0.842 mm-1, F(000)=952, GOF= 1.072, R=0.065 4, wR=0.146 8[I>2σ(I)]. There are two crystallographically independent Co(Ⅱ) ions in the title complex. The Hisor2- and 4,4′-bpy link the metal ions into 2D grids with dimension of 0.522 3 nm×1.138 8 nm. There are O—H…O and N—H…O hydrogen bonds in the complex resulting in the formation of 3D network with 1D channels, in which are free 4,4′-bpy molecules.     

碳包覆Li3V2(PO4)3:溶胶-凝胶法合成及性能

利用V₂O₅、LiOH·H₂O、H₂O₂、NH₄H₂PO₄与柠檬酸为原料,通过溶胶-凝胶法合成了碳包覆的Li₃V₂(PO₄)₃复合正极材料。采用XPS、XRD、SEM、TEM、拉曼光谱和电化学方法对材料的性能进行了研究。还研究了其结构与焙烧温度、样品电导率和电化学性能的关系。研究表明复合材料具有空间群为P2₁/n的单斜结构,表面包覆粗糙多孔的碳层。在800 ℃下制备的碳包覆样品的电子导电率高达9.81×10^-5 S·cm^-1,约为高温固相氢气还原法制备的未包覆碳Li₃V₂(PO₄)₃的10000倍。测试结果表明碳包覆Li₃V₂(PO₄)₃的电化学性能远优于未包覆碳的样品。在3.0～4.3 V电压范围内,以0.1C和2C倍率充放电时,碳包覆的Li₃V₂(PO₄)₃具有高比容量(分别为128和109 mAh·g^-1)和优异的循环性能。