Sr、Mg与Fe复合掺杂镓酸镧基离子导体的制备与电性能研究

探讨了采用固相反应法合成碱土金属Sr、Mg与过渡金属Fe复合掺杂的镓酸镧基ABO。型氧化物La0.8sSr0.2Ga0.75Mg0.20Fe0.05O2.815（LSGMF）；利用热分析仪、EDS、XRD、SEM、直流四端子法等对LSGMF复合氧化物的形成过程、微区成分、晶体结构、显微组织及导电性等进行研究。分析表明：样品的烧结温度不能低于1300℃；EDS结果证实合成的LSGMF样品中杂质元素很少，纯度较高；XRD分析表明：经1350℃烧结合成的LSGMF样品中出现了LaSrGa3O7和LaSrGaO4等杂相，而经1400℃烧结则获得了单一正交钙钛矿结构；电性能测试结果表明：在400—850℃温度区间，其电导率与温度的关系符合Arrhenius定律，说明合成的复合氧化物LSGMF为氧离子导体，且离子迁移活化能0．6656eV（〈leV）；Sr、Mg和Fe复合掺杂氧化物LSGMF与仅Sr、Mg双掺杂氧化物LSGM相比具有更高的离子电导率，说明少量过渡金属Fe的掺杂，可提高离子电导率。     

用柠檬酸-硝酸盐合成La0.8Sr0.2Ga0.85Mg0.15O3-δ及其性能

用柠檬酸-硝酸盐水系溶液为前驱体合成了具有钙钛矿结构的中温电解质La_(0.8)Sr_(0.2)Ga_(0.85)Mg_(0.15)O_(3-s-δ)(LSGM)。用DTA-TGA和X射线衍射仪分析了LSGM材料中钙钛矿相的形成过程,用热膨胀仪和交流复阻抗谱研究了样品的烧结、热膨胀和电学性能。研究结果表明:用柠檬酸-硝酸盐溶液制备LSGM所得到的非晶产物在800℃时开始形成钙钛矿相,1400℃烧结6 h已经完全转变成稳定钙钛矿相,LSGM样品在1450℃烧结6 h,相对密度已经达到98％。1450℃烧结6 h的LSGM样品阻抗谱研究表明:与固相法制备的LSGM相比,用柠檬酸-硝酸盐溶液合成的LSGM晶界电阻和杂相电阻都很小,不影响样品的电导。表明用湿化学法合成LSGM有利于提高纯度,改善导电性能。850℃时样品的电导率为6.0×10~(-2)S/cm,900℃时单电池的最大输出功率密度为12.2 mW/cm~2,短路电流密度达刭55.2 mA/cm~2。     

复合掺杂钙钛矿氧化物La0.6Sr0.4-xCaxCo1-yNiyO3-δ阴极的制备和电性能

采用固相反应法合成了中温固体氧化物燃料电池新型复合掺杂阴极La0.6Sr0.4-xCaxCo1-yNiyO3-δ（LSCCN）钙钛矿材料。借助XRD对不同掺杂含量所制备的粉体的成相过程和晶体结构进行了研究。实验结果表明：当x=0.4时,Ca元素已经不能很好的掺入到LaCoO3晶格中去。Ni元素含量较小的情况下,不会影响材料的晶体结构,不过当NiO含量稍有增高,制备的粉体的结构发生了明显的变化,已不再具有钙钛矿型的晶体结构,出现了较强的四方K2NiF4结构的LaSrCoO4衍射峰。将制备的LSCCN粉体掺入一定的淀粉和粘结剂制备成固体氧化物燃料电池（SOFC）的阴极。在空气气氛下使用直流四探针法测量了样品从100℃到800℃的电导率值,发现LSCCN系列材料中保持了钙钛矿结构的阴极片具有很高的电导率值,其中Ca2+和Sr2+掺杂各半的情况下制备的阴极片的电导率值最高。掺入较多的Ca2+或较多的Ni2+不仅影响了材料的单一的晶体结构,并且大大降低了材料的电导率值。     

Mg2+和Sr2+掺杂对CaCu3Ti4O12陶瓷微观结构与介电性能的影响

采用固相反应法分别制备了Mg2+及Sr2+掺杂的Ca1-xMgxCu3Ti4O12和Ca1-xSrxCu3Ti4O12(x=0、0.1、0.2)陶瓷,利用XRD和SEM分别对陶瓷的物相结构和微观形貌进行了分析,并对其介电性能进行了测试.结果表明,Mg2+的掺杂易引起CaCu3Ti4O12(CCTO)化学计量比的偏失,同时陶瓷的致密化程度受到影响,介电常数也显著降低.而Sr2+的掺杂不仅对CCTO陶瓷物相结构影响不大,而且可以促进陶瓷晶粒的长大,并有效降低了CCTO陶瓷的烧结温度.当Sr2+掺杂量为0.2、测试频率在1 k-2.5kHz时,介电常数为104左右,介电损耗在0.05-0.1之间,介电综合性能比纯CCTO陶瓷有所提高.     

Mg2Si基热电材料的制备与掺杂研究现状

热电材料是一种性能优越的环境友好型材料,它能够直接把电能和热能相互转化,是目前新技术能源材料领域的关键材料.Mg2Si基半导体是一种新型的中温区热电材料,具有热电值高,原料无毒害等优点,由于镁的活性较高,如何制备出性能更加优良的Mg2Si基块体热电材料成为本领域研究的重点.本文简要介绍了Mg2Si基热电材料的基本性质,阐述其各种制备方法和掺杂研究现状,并展望其未来研究方向.     

Ti(C,N)基金属陶瓷抗弯强度的价电子判据研究

利用固体分子经验电子理论,计算了金属陶瓷中三元复合陶瓷相（Ｔｉ,Ｍｏ,Ｗ）Ｃ,四元复合陶瓷相（Ｔｉ,Ｍｏ,Ｗ,Ｎｂ）Ｃ和（Ｔｉ,Ｍｏ,Ｗ,Ｔａ）Ｃ五元复合陶瓷相（Ｔｉ,Ｎｏ,Ｗ,Ｎｂ,Ｔａ）Ｃ的价电子结构,探讨陶瓷相的价电子结构与金属陶瓷抗弯强度关系,提出判据关系式,此外,还进行了抗弯强度的实验验证。     

(Ti,Mo,W,Ta,V,Nb)(C,N)多元陶瓷相的价电子结构

运用固体与分子经验电子理论(EET理论)计算了(Ti,Mo,W,Ta,V,Nb)(C,N)多元陶瓷相的价电子结构.结果表明,价电子结构参数(nA)随碳化物添加量的增加而增加.不同碳化物对价电子结构参数的影响不同,其中VC的影响最为显著.价电子结构参数(nA)可以用来评价金属陶瓷的力学性能,提出了相关的判据关系式.     

Fe3C型碳化物与人造金刚石晶面价电子结构分析

基于高温高压合成金刚石过程中铁基触媒及其金属包膜中存在大量Fe3C型碳化物的实验结果,利用余氏理论(empirical electron theory of solid and molecule,EET)分析了Fe3C型碳化物内C-C键组成晶面和与之对应的金刚石晶面的共价电子密度,发现它们在一级近似下存在连续性,满足程氏理论(improved Thomas-Fermi-Dirac theory advanced by Cheng,TFDC)提出的原子界面边界条件.分析结果表明:高温高压下的金刚石单晶生长与Fe3C型碳化物的分解有关.在4种Fe3C型碳化物中,(Fe,Ni)3C内的C-C键组成晶面和与之对应的金刚石晶面的共价电子密度连续的组数最多.因而认为:合成金刚石过程中使用含镍的铁基触媒,在高温高压下形成的(Fe,Ni)3C作为碳源,最容易转变为金刚石.     

Bi掺杂Ba0.6Sr0.4TiO3陶瓷的研究

本文采用传统的陶瓷工艺合成了Ba0.6Sr0.4TiO3陶瓷,研究了Bi掺杂对材料参数ε、tanδ和E的影响,并探讨了相关的掺杂改性机理。结果表明：适量的Bi能够改善陶瓷的介电性能,同时细化陶瓷的晶粒尺寸。     

室温离子液体1-丁基-3-甲基咪唑磷酸二丁酯的电导率研究

利用磷酸三丁酯与N-甲基咪唑在恒温150℃下一步合成了离子液体1-丁基-3-甲基咪唑磷酸二丁酯,考察了其在丙酮,水,DMF,乙酸溶剂中的电导率及摩尔电导率。实验发现该离子液体在不同溶剂中的电导率(κ)相差很大,其顺序为κa(水)>κb(DMF)>κc(丙酮)>κd(乙酸)。在相同温度下,电导率及摩尔电导率随浓度的增大而增大;在相同浓度下,电导率及摩尔电导率随温度的升高而增大。     

Influence of Microwave‐Assisted Pechini Method on La0.80Sr0.20Ga0.83Mg0.17O3–δ Ionic Conductivity

With the aim of investigating the microwave influence on the electrolyte material properties, La_0.80Sr_0.20Ga_0.83Mg_0.17O_2.815 was prepared by both a conventional and a microwave‐assisted sol–gel Pechini method. With respect to the conventional Pechini method (hereafter SGP), the microwave assisted process (hereafter MWA‐SGP) guaranteed a faster procedure, reducing the time needed to remove the excess solvents to complete the polyesterification reaction from some days to a few hours. In fact, when a MWA‐SGP method was used, powders having higher phase purity were obtained. The sintering process at 1,450 °C of the powders prepared by both methods yielded pellets with similar density values (≥92% of theoretical). Nevertheless, only by microwave‐assisted process single‐phase products were obtained and no secondary phases such as tetragonal LaSrGaO₄ and LaSrGa₃O₇ were detected. These by‐products have been demonstrated to be detrimental for conductivity. Indeed, pellets obtained by MWA‐SGP method showed oxygen ionic conductivity values higher (about 30–40%) than those checked for SGP samples, thus demonstrating the important role of the microwave process on reducing time and costs and on improving the electrolyte properties.     

LaIn1-xFexO3电解质材料的合成、结构及电学性能研究

以柠檬酸为分散剂,采用溶胶-凝胶法与微波加热技术,合成Fe3+掺杂LaInO3(LaIn1-xFexO3, 0.0≤x≤0.5)系列电解质粉体.分别采用XRD、交流复阻抗测量技术,对LaIn1-xFexO3电解质的结构与电学性能进行了表征.结果表明:800℃微波加热20min,制得LaIn1-xFexO3电解质.在组成范围内,Fe3+掺杂的LaInO3系统形成稳定的取代型固溶体,随着Fe3掺杂量的增加,Laln1-xFexO3的晶胞常数逐渐减小,电解质的氧离子电导率逐渐升高.     

Ionic Conductivity and Discharge Characteristic Studies of PVA-Mg(CH3COO)2 Solid Polymer Electrolytes

Ion conducting solid polymer electrolytes based on a polymer polyvinyl alcohol (PVA) complexed with magnesium acetate (Mg(CH₃COO)₂) were prepared by solution cast technique. Various experimental techniques, such as XRD, DSC, composition-dependent conductivity, temperature-dependent conductivity, and transport number measurements are used to characterize these polymer electrolyte films. The transference number data indicated the dominance of ion-type charge transport in these polymer electrolyte systems. An electrochemical cell with the configuration Mg/(80PVA + 20Mg(CH₃COO)₂)/(I₂ + C + electrolyte) has been fabricated and its discharge characteristics were studied. The Open Circuit Voltage (OCV) is 1.84 V.     

Effect of Prolonged Duration of Gelatinization in Starch and Incorporation with Potassium Iodide on the Enhancement of Ionic Conductivity

Three systems of starch-based crust electrolytes were prepared using various gelatinization times, various weight percentages (wt%) of starch, and various wt% of starch incorporated into potassium iodide. All the samples were subjected to electrochemical impedance spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and transference number measurements. Electrochemical impedance spectroscopy shows that 1.7?wt% of starch has maximized the room temperature conductivity of the electrolyte to 1.4587?×?10^?4?S?cm^?1. The conductivity was enhanced to 4.5278?×?10^?4?S?cm^?1 on the increment of starch’s wt% from 1.7 to 3.2. This conductivity was further enhanced to 3.4609?×?10^?3?S?cm^?1 on the addition of 0.3?wt% of potassium iodide. The conductivity enhancement was found due to the formation of glucosyl carboxonium ions. The effect of longer heating time in gelatinization is attributed to the formation of glucosyl carboxonium ions. X-ray diffraction spectroscopy affirms the reduction in crystallinity of starch. Scanning electron microscopy analysis shows the porous morphology of starch electrolyte, and addition of potassium iodide shows the morphology of bean nuts like particles seated on the pores. Fourier transform infrared confirms the degradation of starch. Transference number measurements of the crust electrolyte shows that ions are the dominant conducting species. All the results are authenticating that the conductivity enhancement in starch-based crust electrolyte is due to starch and the addition of inorganic salts.     

室温离子液体1-烷基-3-甲基咪唑硫酸甲酯的合成及电导率研究

利用硫酸二甲酯分别与N-甲基及N-丁基咪唑在室温下反应,一步合成了离子液体1-甲基-3-甲基咪唑硫酸甲酯和1-丁基-3-甲基咪唑硫酸甲酯,测定了在不同温度下离子液体的电导率.结果表明:随着温度的升高,离子液体的电导率迅速增加;同时电导率与温度的变化关系符合多项式方程和Vogel-Tammann-Fulcher(VTF)方程.     

磁性离子液体1-甲基-3-烷基咪唑四卤化铁盐的合成及其物性表征

合成了4种1-甲基-3-烷基咪唑四氯化铁盐[Cnmim]FeCl4(n=2, 4, 6, 8)及3种1-甲基-3-丁基咪唑四卤化铁([C4mim]FeX4, X=Cl, Br)磁性离子液体,光谱结果表明,[Cnmim]FeCl4及[C4mim]FeBr4中阴离子单一,而[C4mim]FeClBr3及[C4mim]FeCl3Br中的阴离子为FeBr4-, FeBr3Cl-, FeCl2Br2-, FeCl3Br-, FeCl4-的混合物. 测定了其密度、粘度、电导率,磁性离子液体密度较大,25℃时为1.25~1.94 g/cm3;粘度较小,25℃时为21~65 mPa×s;电导率较大,30℃时为0.23~1.37 S/m. 并研究了其物性随温度及结构的变化规律.     

3-3型与1-3型多孔锆钛酸铅陶瓷的结构和性能

以叔丁醇为溶剂和成孔模板,采用冷冻–干燥工艺制备1-3型多孔锆钛酸铅（lead zirconate titanate,PZT）陶瓷,采用凝胶注模工艺制备3–3型多孔PZT陶瓷,利用扫描电子显微镜和压汞仪对多孔陶瓷的形貌和孔径分布进行表征,利用阻抗分析仪测试多孔陶瓷的介电常数,利用Piezo–metersystem测量仪...     

Conductivities of AlCl3/Ionic Liquid Systems and Their Application in Electrodeposition of Aluminium

Solubilities and conductivities of anhydrous AlCl3 in six kinds of ionic liquids (ILs) were measured. Among the six kinds of ILs [bmim]Cl, [bmim]Br, [bmim]BF4, [bmim]PF6, [emim][EtSO4] and [bmim][HSO4], anhydrous AlCl3 could be dissolved in the first five kinds but was hardly dissolved in [bmim][HSO4]. The results showed that the nominal solubilities of AlCl3 in ILs increased in the order of [bmim][HSO4] < [bmim]PF6 < [emim][EtSO4] < [bmim]BF4 < [bmim]Cl < [bmim]Br. Conductivities of the AlCl3/ILs systems depended apparently on the nominal molar ratio of AlCl3 to ILs. The conductivities of AlCl3/[bmim]Cl, AlCl3/[bmim]Br and AlCl3/[bmim]PF6 systems had a similar tendency as a function of the nominal molar ratio, that is, as the molar ratio was increased, conductivities increased first and then decreased, with the maximum conductivity obtained at approximately 0.9:1, 1.0:1 and 0.5:1, respectively. Conductivities of the AlCl3/[bmim]BF4 exhibited a dentate change and decreased with the molar ratio of AlCl3 to [bmim]BF4 increasing in general. With the increasing of the anhydrous AlCl3 amount in [emim][EtSO4], conductivity of AlCl3/[emim][EtSO4] monotonically decreased. AlCl3/[bmim]Cl system was chosen as the electrolyte for the electrodeposition of Al. Preliminary experimental results showed that dense, adherent and homogeneous Al coatings could be electrodeposited on stainless steel by means of constant potential technique and the surface coverage was quite satisfactory.     

Fabrication,Physicochemical Characterizations and Electrical Conductivity Studies of Modified Carbon Nanofiber-Reinforced Epoxy Composites: Effect of 1-Butyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquid

This study presents the fabrication of carbon nanofiber-reinforced epoxy nanocomposites using 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid as filler dispersant. FTIR and XRD measurements were utilized to assess structural attributes and crystallographic change in the composites. In addition, morphological studies were performed by field emission scanning electron microscope while the extent of miscibility between epoxy and IL was computed by Accelrys Materials Studio Software. The conductivity measurement was performed by two point impedance analyzer and result demonstrated increase in the electrical conductivity from ～10^?7 to ～10^?5?S?cm^?1 compared to pristine epoxy composite.