Ti掺杂对Ba0.5Sr0.5Co0.8Fe0.2O3-δ陶瓷透氧膜性能的影响

采用EDTA—柠檬酸双络合法合成了Ba0.5Sr0.5(Co0.8Fe0.2)1-xTixO3-δ(x=0～0.2)粉体,并通过干压成型和高温烧成制备了片状致密陶瓷膜.研究了钙钛矿结构中B位Ti掺杂量对合成粉体物相结构和相应的膜的微观结构、电导特性、氧渗透性能和热膨胀性能等的影响.结果表明,5～20 mol/％Ti掺杂...     

La0.7Sr0.3Ga0.6Fe0.4O3-δ氧离子导体材料的制备与表征

以相应的金属氧化物和盐为原料,通过甘氨酸-硝酸盐法(GNP)合成出La0.7Sr0.3Ga06Fe04O3-δ(LSGF)粉末,经压制、烧结后,得到LSGF烧结体试样.采用X射线衍射仪(XRD)对所得前驱体及其煅烧后粉体的相组成进行分析;采用扫描电镜(SEM)及X射线冠电子能谱仪(EDS)对烧结体的微观组织和成分进行了观察,还对烧结体的致密度、电导率和热膨胀系数等进行了测试分析.实验结果表明,甘氨酸-硝酸盐法所制备的前驱体粉末在700℃煅烧5h后可获得具有单一钙钛矿结构的LSGF粉末,其晶粒尺寸在45 nm左右,所制备的LSGF烧结体在400～900℃范围的电导率在3.97～4.42 S·cm-1之间,热膨胀系数在9.2 ×10-6 ～11.12 ×10-6 K-1之间.     

新型Al2O3掺杂的SrCo0.8Fe0.2O3-δ混合导体透氧膜材料的性能

采用固相反应法制备了Al₂O₃掺杂的SrCo_0.8Fe_0.2O_3-δ(SCFA)新型钙钛矿型混合导体材料.对材料进行的结构分析表明,Al³⁺离子进入SrCo_0.8Fe_0.2O_3-δ(SCF)晶胞间隙位,降低了材料的氧非化学计量系数,并有效提高了材料的结构稳定性;对不同厚度的SCFA3［Al₂O₃掺杂量为3%（质量）］片式膜的氧渗透性能测定结果表明,SCFA3膜的氧渗透过程受到表面交换过程和体扩散过程的共同影响,其临界厚度约为131.5 μm;二氧化碳热分解(TDCD)耦合甲烷部分氧化(POM)膜反应过程（反应温度1173 K）表明,Al₂O₃掺杂的SrCo_0.8Fe_0.2O_3-δ较SrCo_0.4Fe_0.2O_3-δ (SCFZ) 具有更加优异的稳定性.     

钙钛矿型复合氧化物陶瓷膜的制备及其透氧性能

用低温燃烧法合成了La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF)钙钛矿型复合氧化物电子一氧离子混合导体材料。采用微粉浆料相变纺丝技术制备了具有多孔层和致密层的管状中空非对称陶瓷膜。考察了温度以及吹扫气氦气流速对膜的透氧性能的影响。结果表明:当温度升高到700℃,氧通量显著增大;增加氦气流速也使透氧速率增大,但是当氦气流速增大到某一值时,透氧速率基本恒定。不同温度下达到最大透氧速率时的氦气流速不同。透过侧氧分压为1.7kPa、温度为900℃、平均厚度为0.45mm的LSCF管状中空膜的透氧速率达2.2×10-7mol/(cm2·s)。     

溶胶-凝胶法合成SrFe0.7Cu0.3O3-δ混合导体透氧膜材料的研究

利用溶胶-凝胶法制备了SrFe0.7 Cu0.3O3-δ混合导体透氧膜材料粉体,采用TG-DSC、XRD进行分析表征,考察了不同制备条件下溶胶.凝胶的性质、所制备的粉体的物相组成.结果表明:溶胶在pH=4左右、脱水温度80℃、柠檬酸与总金属离子物质的量配比C/Mn+=2、干凝胶在900℃下焙烧保温5 h,可制得结晶度高、具有单一稳定钙钛矿结构的粉体.     

非对称LSCF中空纤维透氧膜的制备及性能

采用溶胶–凝胶法制备了具有钙钛矿型结构的La0.6Sr0.4Co1–yFeyO3–δ(LSCF,y=0.2,0.5或0.8)氧化物,然后以相转化烧结技术制备了LSCF中空纤维透氧膜,考察了凝固浴与Co/Fe摩尔比对LSCF中空纤维膜微结构及透氧性能的影响.使用70％(质量分数)NMP与30％乙醇的混合液作为内凝固浴,去...     

Ferroelastic mechanical behaviour of porous La0.6Sr0.4Co0.2Fe0.8O3−δ

The present study investigates the mechanical behaviour of ferroelastic La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ with porosity ranging from 0.9% to 26.1% under uniaxial compression at room temperature. Both dense and porous samples have ferroelastic domains and exhibit ferroelastic mechanical behaviour. The apparent modulus, compressive strength and critical stress of the material dramatically decrease with increasing porosity, exhibiting exponential relationships. Comparison of the mechanical behaviours of samples with similar porosity but different porous structures reveals that the ferroelastic mechanical behaviour depends not only on porosity but also structural factors such as pore size and distribution.     

溶胶-凝胶法制备La1-xSrxCoyFe1-yO3-δ混合导体透氧膜粉料的研究

运用现代测试分析手段XRD、TEM和DTA等 ,对溶胶—凝胶法制备La1-xSrxCoyFe1-yO3 -δ混合型导体透氧膜粉料的工艺和性能进行了较详细的研究。实验结果表明 :溶胶的pH =6 - 8,脱水温度在 80℃左右 ,干凝胶在95 0 - 10 0 0℃下保温 2小时焙烧 ,可获得透氧性能较高的La1-xSrxCoyFe1-yO3 -δ粉料。     

La0.6Sr0.4Fe0.8Co0.2O3的甘氨酸-硝酸盐法合成与表征

采用甘氨酸-硝酸盐法(GNP)制备La0.6Sr0.4Fe0.8Co0.2O3初级粉料, 研究甘氨酸用量对初级产物和热处理产物的晶体结构和显微形貌的影响, 并用直流四探针法测量烧结体的电导率.在286.8～365.7 ℃范围内, 初级粉料中残余有机物和残碳氧化分解.钙钛矿结构La0.6Sr0.4Fe0.8Co0.2O3在720.9 ℃左右形成.经750 ℃(保温1 h)热处理即可制得单相钙钛矿结构La0.6Sr0.4Fe0.8Co0.2O3.甘氨酸-硝酸盐法所制粉体颗粒细小, 有轻微烧结现象, 这是由燃烧温度高导致的, 经短时间研磨后团聚状况可得到改善.与固相合成法相比, GNP法所制样品的电导率较高.     

CaFe0.2Ti0.8O3-δ混合导体的电导和氧渗透性能研究

采用固相反应法制备了致密的高温混合导体ＣａＦｅ０．２Ｔｉ０．８Ｏ３－δ,测量它在９００－１１００℃的总电导率为０．０８－０．１１Ｓ／ｃｍ,氧渗透率为１０＾－８－１０＾－１０ｍｏｌ／ｃｍ＾－２．ｓ结合总电导与氧渗透的数据计算出样品的电子和离子导电率,在１１００℃时分为０．１１和８．５×１０＾－３Ｓ／ｃｍ;氧渗透活化能约为１７０ｋＪ／ｍｏｌ;氧离子和电子电导活化能分别为１７９±６和２２±２ｋＪ／ｍｏｌ     

Nanofiber-structured Pr0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ-Gd0.2Ce0.8O1.9 symmetrical composite electrode for solid oxide fuel cells

In this research, nanofiber-structured Pr_0.4Sr_0.6Co_0.2Fe_0.7Nb_0.1O_3-δ (PSCFN) electrode scaffolds were impregnated with Gd_0.2Ce_0.8O_1.9 (GDC) nanoparticles to prepare PSCFN-GDC nanofiber-structured composite electrodes, which could function well as a novel electrode material for symmetrical solid oxide fuel cells (SSOFCs). The polarization resistances of PSCFN-GDC (1:0.56) composite electrodes as cathode and anode were 0.044 and 0.309 Ω cm² at 800 °C, respectively, indicating that the composite electrodes demonstrated excellent electrochemical performances for both oxygen reductions and fuel oxidation reactions. La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ (LSGM) electrolyte-supported single cells with the PSCFN-GDC symmetrical composite electrodes showed excellent long-term stability in wet H₂ (97% H₂-3% H₂O) and wet CH₄ (97% CH₄-3% H₂O) for 100 h with constant current density at 800 °C. A conversion electrode method was applied by interchanging the atmosphere of cathode and anode to solve the problem of PSCFN-GDC symmetrical single cell's carbon deposition in wet CH₄. After working three cycles for 384 h, carbon deposition was not found in the symmetrical electrode scaffold. Taken together, the results described above demonstrated that the PSCFN-GDC composite material acted as a promising symmetrical electrode for SSOFCs, and the conversion electrode method would make for a good application to process carbon deposition generated by hydrocarbon fuels.     

硅橡胶—玻璃中空纤维富氧膜的制备

以玻璃粉为基膜材料,通过溶液纺丝技术制备了玻璃中空纤维基膜。将其置于一定浓度的硅橡胶(PDMS)溶液中浸渍,得到了硅橡胶-玻璃中空复合膜。利用电子扫描显微镜、红外光谱仪、X-射线光电子能谱仪分析复合膜的微观形态和元素变化。探究了浓度、浸渍次数对硅橡胶-玻璃中空复合膜富氧性能的影响。     

Bi0.6Ca0.4Mn0.2Fe0.8O3的介电性能研究

用溶胶-凝胶法制备了Bi0.6Ca0.4Mn0.2Fe0.8O3样品,通过检测样品的X衍射、介电谱和阻抗谱,对其微观结构和介电性能进行了研究.研究表明:随着频率的增加,样品的介电常数逐渐减小,而随着温度的增加,样品的介电常数逐渐加大.同时发现,通过在Bi0.6Ca0.4MnO3的Mn位进行Fe掺杂,明显的改善了Bi0....     

溶胶—凝胶法制备La1—xSrxCoyFel—yO3—δ混合导体透氧膜粉料的研究

运用现代到试分析手段XRD、TEM和DTA等，对溶胶—凝胶法制备La1-xSrxCoyFel-yO3-δ混合型导体透氧膜粉料的工艺和性能进行了较详细的研究。实验结果表明：溶胶的pH＝6—8，脱水温度在80℃左右，干凝胶在950—1000℃下保温2小时焙烧，可获得遂氧性能较高的La1-xSrxCoyFel-yO3-δ粉料。     

固体氧化物燃料电池La0.6Sr0.4Co0.2Fe0.8O3–δ–Ce0.8Sm0.2O1.9纳米结构复合阴极的性能衰减行为

利用浸渍法制备了以La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3–δ)(LSCF)为催化相、Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)为骨架的纳米结构复合阴极,并将LSCF–SDC复合阴极在600℃保温500 h,随后再用HCl腐蚀,研究了LSCF–SDC纳米结构复合阴极性能衰减的机理。结果表明:LSCF–SDC纳米结构复合阴极在600℃保温处理500 h后,阴极的极化电阻从0.21Ω·cm~(–2)增加到0.25Ω·cm~(–2),增加了19%,对其腐蚀处理后阴极极化电阻降为0.15Ω·cm~(–2),阴极催化活性的降低主要与氧在阴极表面的吸附与解离过程有关;阴极相组成和表观形貌没有明显的变化;保温处理后Sr~(2+)在阴极表面以SrO的形式富集。     

荷电中空纤维复合膜及其正渗透性能研究

以聚丙烯中空纤维微滤膜为底膜、羧甲基纤维素钠为功能材料、氯化铁为交联剂,采用溶液涂覆-交联工艺制备了表面荷电的中空纤维复合膜,将该中空纤维复合膜用于正渗透(FO)过程,研究了汲取液盐含量、原料液流速等对FO通量的影响。结果表明,制备的荷电中空纤维复合膜可用于FO过程,以蒸馏水为原料液、Na2SO4水溶液为汲取液,采用PRO模式进行FO试验,当原料液与汲取液体积流量均为15 mL/min、汲取液浓度为0.5 mol/L时,FO水通量为12.3 L/(m2.h),盐通量与水通量的比为1.42 g/L。     

制备方法对Pr0.6Sr0.4FeO3-δ结构与性能的影响

采用甘氨酸-硝酸盐、Pechini、柠檬酸-硝酸盐以及尿素-硝酸盐等4种不同的湿化学方法,制备了Pr0.6Sr0.4FeO3-δ复合氧化物粉体.用X射线衍射分析了材料中钙钛矿物相的形成过程及其与中温电解质的化学相容性.用扫描电镜研究了样品的微结构.结果表明:不同方法得到的素坯经1 000℃煅烧2 h即形成钙钛矿结构的固溶体.Pechini法制备的非晶产物煅烧后钙钛矿物相的纯度最高.素坯经1200℃煅烧2 h,所得陶瓷体的总气孔率均为43%～49%;体积密度以柠檬酸-硝酸盐法粉体的样品最高,甘氨酸-硝酸盐法最低.在室温到800℃的温度范围内,Pechini法制备的陶瓷体的热膨胀系数为12.15×10-6/K,与电解质Sm0.2Ce0.8O1.9(SDC)及La0.8Sr0.2Ga0.8Mg0.2O3-δ(LSGM)的数值一致.X射线衍射揭示产物与中温电解质SDC及LSGM具有良好的化学相容性.     

The role of manganese substitution on the redox behavior of La0.6Sr0.4Fe0.8Mn0.2O3-δ

Perovskite oxides such as ferrites have been widely investigated for their remarkable electrochemical activity as SOFC electrodes. However, their phase instability in reducing conditions remains an issue for anode application. The role of Mn substitution into B-site of La_0.6Sr_0.4FeO_3-δ (LSF) perovskite oxide was investigated. New insights on the structural evolution of La_0.6Sr_0.4Fe_0.8Mn_0.2O_3-δ (LSFMn) upon high temperature reduction were revealed. In oxidizing atmosphere, Mn substitution reduces the oxygen vacancy concentration while, switching to reducing conditions, it drives the transition from rhombohedral perovskite to single Ruddlesden-Popper phase, affecting the Fe⁰ exsolution. Redox-cycles of LSFMn were investigated and the properties of re-oxidized compounds were highlighted. The effect of Mn substitution on perovskite conductivity was also evaluated both in oxidizing and reducing conditions.     

混合导体透氧膜材料的设计与应用

混合导体透氧膜材料在高温下具有氧离子－电子混合导电性能,在纯氧制备、膜反应器以及固体燃料电池等方面展现出广阔的应用前景。本文对近年来混合导体透氧膜材料的开发和在甲烷部分氧化等方面的应用进行了详细综述,重点介绍了本课题组在此领域的工作。