La0.7Sr0.3Co1-yFeyO3-δ阴极材料的制备与导电性能研究

采用低温燃烧合成法制备了用作中低温固体氧化物燃料电池的阴极材料La0.7Sr0.3Co1-yFeyO3-δ(y=0.00,0.20,0.25,0.30,0.35,0.40).分别利用TG-DSC、XRD表征了La0.7Sr0.3Co1-yFeyO3-δ形成过程的晶型演化行为和物相组成,结果表明该粉体经900℃热处理后可形成钙钛矿结构,随着Fe含量增加,衍射峰向低角度方向偏移.利用直流四端子法测试了La0.7Sr0.3Co1-yFeyO3-δ的电导率,结果表明样品的电导率随Fe含量的增加而降低.在所测量的温度范围内,y=0样品的电导率随温度升高而减小,符合类金属导电行为;其余样品的电导率随温度的升高而增大,服从半导体导电机理.在测试温度范围内,材料的电导率均大于600 S·cm-1.     

钙钛矿氧化物La0.3Ca0.7MnO3的磁性质

采用固相反应法制备了样品La0.3Ca0.7MnO3. 通过测量样品的M-T曲线、 M-H曲线和ESR曲线, 研究了La0.3Ca0.7MnO3的磁性质. 结果表明 在262 K时形成电荷有序相(CO相). 当T＞262 K时, 表现为顺磁;当T＜190 K时, 表现为长程反铁磁(在AFM本底中存在少量FM成分);从262～190 K(TCO), 随温度降低在电荷有序态下从顺磁向反铁磁转变.     

La0.9Sr0.1MnO3微波合成和晶格热膨胀系数的研究

采用微波法合成固体氧化物燃料电池负极材料La0.9Sr0.1MnO3,并用动态高温粉末X射线衍射技术,对微波合成的产物La0.9Sr0.1MnO3从室温到1200℃之间的晶格热膨胀系数进行了测定。实验结果表明:在测试温度范围内,La0.9Sr0.1MnO3的晶格膨胀系数与温度呈线性关系。微波法合成的La0.9Sr0.1MnO3的晶格热膨胀系数为:△a/a0△T=8.9×10-6/℃、△c/c0△T=11.2×10-6/℃和△V/V0△T=29.3×10-6/℃。在实验温度区间内未发现样品有明显的相变或结构转变现象。     

Variation of optimum yttrium doping concentrations of perovskite type proton conductors BaZrl_xYxO3-~ （0~~~_0.3） with temperature

A solid state reaction method was used to prepare the perovskite-structured compounds BaZrl-xYxO3-a （x=0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3）. The X-ray diffraction （XRD） pattern indicated that the target perovsldte phases were obtained. With increasing Y con- centration the unit cell parameters of BaZrl-xYxO3-a samples were expanded, and Y doping became more difficult. However, high synthesis temperature is helpful to promote Y doping. The SEM results showed that the samples exhibited poor sinterability with in- creasing Y-doping content. Thermal gravimetric （TG） curves analysis showed the more mass decreasing of BaZrl-xYxO3-a （0≤x≤0.3） samples at high temperature with more Y doping and more proton introducing. The electrochemical impedance spectra （EIS） of specimens showed that conductivities of BaZrl_xYxO3（0≤x≤0.3） increased with increasing temperature from 300 to 900 ℃ in wet air. At 900 ℃, the conductivity of BaZrl-xYxO3-a （0≤x≤0.3） first increased with increasing doped amount of Y, and reached the high- est value of 1.07x 104 S/cm when x was 0.2, then decreased gradually with further increasing Y content. At 600 ℃, BaZr0.75Y0.2503-a displayed the highest conductivity, while the conductivity of BaZro.rYo.303-a was the highest at 300 ℃. The results indicated that there should be an optimum Y doping concentration yielding the highest conductivity at a constant temperature, and the optimum Y doping concentration should increase in the humidity atmosphere as the temperature decreases. So increasing the Y-doping concen- tration is helpful to improve the conductivities of BaZrl-xYxO3-a materials at low temperature.     

中温固体氧化物燃料电池La1-xBaxFeO3-δ阴极材料的制备及性能表征

采用柠檬酸-硝酸盐自蔓延燃烧法合成了中温固体氧化物燃料电池阴极材料La_1-xBa_xFeO_3-δ(LBF)(x=0,0.1,0.2,0.3,0.4,0.5)。通过X射线衍射(XRD)、直流四端引线法和热膨胀仪分别对LBF的晶体结构、电导率和热膨胀系数进行了研究,分析了Ba掺杂量对材料性能的影响。同时制备了电解质Gd_0.1Ce_0.9O_2-δ(GDC),构建对称电池LBF/GDC/LBF并进行了电化学性能测试,用扫描电子显微镜观察(SEM)对称电池的断面微结构,交流阻抗谱测试极化阻抗。结果表明,合成的阴极材料LBF均为钙钛矿结构,A位Ba掺杂提高了材料的电导率,同时增大了材料的热膨胀系数,改善了阴极材料与电解质GDC的热膨胀匹配性。SEM结果显示对称电池具有理想的微观结构,阴极与电解质之间的界面展现出良好的烧结结合;电化学交流阻抗分析结果表明,A位Ba掺杂可以降低阴极的极化电阻,当Ba²⁺掺杂量为x=0.4时,LBF-0.4具有最小的极化电...     

钙钛矿型复合氧化物La1-xSrxMnO3和(La0.7Sr0.3)1-yKyMnO3的结构及磁性研究

采用溶胶-凝胶法制备了钙钛矿型La1-xSrxMnO3和(La0.7Sr0.3)1-yKyMnO3粉体,研究了溶胶-凝胶法合成条件对样品的比饱和磁化强度的影响.利用XRD对样品结构进行表征,结果表明,Sr的掺入量不影响La1-xSrxMnO3结构,(La0.7Sr0.3)1-yKyMnO3系列样品由于K 的半径与La3 ,Sr2 不匹配,掺杂浓度仅为0.01就已经出现杂相峰,超过0.1时杂峰增多.通过振动样品磁强计测试样品的磁性质,结果表明,x≤0.3的范围内La1-xSrxMnO3系列样品的比饱和磁化强度随着x的增加而增加,当x>0.3后随x的增加而减弱,(La0.7Sr0.3)1-yKyMnO3系列样品的比饱和磁化强度随Y的增加而下降.     

Synthesis and Electrical Properties of La0.6M0.4FeO3-δ （M = Ca, Sr, Ba） as Cathodes for SOFCs

Intermediate-temperature solid oxide fuel cells(IT-SOFCs) have attracted extensively attentionin re-cent years because of the potential to dramatically re-duce the cost of the materials and cell fabrication inaddition to i mprove reliability , portability and long-termperformance stability ,it has been regarded as ahigh green energyin 21st[1].However ,the experi men-tal results identifiedthat the ohmic losses of IT-SOFCslargely occurred from cathode polarization , and theknown cathode mate…     

La1-xSrxCr1-yMnyO3-δ阳极材料的固相合成及导电性能研究

采用固相法制备固体中温氧化物燃料电池(SOFC)阳极材料La1-xSrxCr1-yMnyO3-δ(LSCM), 用X射线衍射(XRD)分析了LSCM材料中钙钛矿相的形成过程, 直流四探针对合成材料的导电性能进行了研究, 碘量法测定了材料中的非化学计量值. 结果表明: 固相法制备所得到的产物分别在1250和1350 ℃下烧结15 h都能得到单一的钙钛矿相;对LSCM样品导电性能研究表明, 其电导率随温度的升高而增加, 在850 ℃时空气气氛下的电导率可达22.04 S·cm-1;LSCM系列材料的电导率随着氧的非化学计量值的增加而提高. 用丝网印刷方式, 制备以LSCM为阳极, La1-xSrxGa1-yMgyO3-δ(LSGM)为电解质, La1-xSrxCo1-yFeyO3-δ(LSCF)为阴极的单电池, 并对其性能进行测试, 最大功率输出密度约100 mW·cm-2.