Electrical properties of La0.6Sr0.4Co1-yFeyO3 cathode material

The electrical properties of La0.6Sr0.4Co1-yFeyO3 （LSCF, y=0-1.0） cathode materials were measured by DC four probes, X-ray photo-electron spectrum （XPS） was also introduced to determine the chemical state of Co, F.e ions in LSCF. It is found that the electrical conductivity of each sample has a maximum value with increasing temperature. XPS analysis shows that Co ion has three different chemical states, corresponding to two with Fe ion. The analyses indicates that the small-polaron hopping mechanism dominates the electron conduction at low temperature, while at high temperature, the three factors such as the thermally activated disproportionation of Co^3＋ ions into Co^2＋ and Co^4＋ pairs, the ionic compensation of oxygen vacancies formed at high temperatures, and Fe^4＋ ions charge compensation preferential to Co^4＋, all contribute to electrical conduction.     

Microstructure of reactive sintered Al bonded Si3N4-SiC ceramics

Aluminium nitride-silicon nitride-silicon carbide （AIN-Si3N4-SiC） composite ceramics were prepared to increase the bending strength and improve the phase structure of Si3N4-based ceramics. The ceramics were made by reactive sintering in N2 atmosphere at 1 360 ℃, using Al as sintering additive. The phase composing of ceramics was identified with an X-ray diffractometer and the microstructure of the materials was studied by scanning electron microscopy. The results indicate that the phase structure is affected remarkably and the interface modality is changed. The interface between Si3N4 and SiC becomes blurry and that between SiC and AlN matches more better at the same time. But the liquid-phase appears during the reactive sintering along with the addition of AI by which the melting point of Si is decreased. The appearance of liquid Si decreases the bending strength of the ceramics. Lower temperature nitrification technic was introduced to avoid the appearance of liquid-phase Si. The optimum addition of Al was investigated by XRD and SEM analysis in order to obtain the maximal bending strength of materials.     

La0.6Sr0.4Co1-yFeyO3系阴极材料的电性能

La1-xSrxCo1-yFeyO3系(LSCF)钙钛矿结构氧化物是一类性能优异的离子-电子混合导体,同时具有良好的化学稳定性和催化活性,有望作为中低温下工作的固体氧化物燃料电池阴极材料的候选材料.本文考察了La0.6Sr0.4Co1-yFeyO3(y=0.2～0.8)系材料的导电机制.XPS光电子能谱分析表明,除了存在小极化子导电机制外,同时还可能存在以下几种机理:1)热激发引起Co3 离子的电荷歧化;2)高温下氧空位生成导致的离子补偿;3)Fe4 较Co4 优先进行电荷补偿.     

La0.6Sr0.4Co1-yFeyO3系阴极材料制备及表征

La1-xSrxCo1-yFeyO3系(LSCF)钙钛矿结构氧化物是一类性能优异的离子-电子混合导体,同时具有良好的化学稳定性和催化活性,有望作为中低温条件下工作的固体氧化物燃料电池阴极材料的候选材料.本文采用固相反应法制备了多孔La0.6Sr0.4Co1-yFeyO3(y=0.2～0.8)氧化物陶瓷,通过XRD,TG/DTA等测试技术研究了LSCF的结构与制备过程,采用直流四探针法测试了样品的电导率,同时考察了这类组成样品的热膨胀系数.结果表明,这类组成的电导率都有着相同的变化趋势,即先随温度升高而增大,至极大值后又开始降低.分析表明,除了存在小极化子导电机制外,同时还可能存在以下几种机理:1)热激发引起Co3 离子的电荷歧化;2)高温下氧空位生成导致的离子补偿;3)Fe4 较Co4 优先进行电子补偿.     

固体氧化物燃料电池材料的研究进展

固体氧化物燃料电池（SOFC）是当今一种先进的能量转换装置，具有能量转换效率高、环境友好、燃料适用性强和无腐蚀等突出优点。该电池通常用陶瓷作组装材料，操作温度为600－1000℃。详细介绍了固体氧化物燃料电池各元件的材料，包括Y2O3稳定化的ZrO2固体电解质，Ni/稳定化ZrO2阳极，掺杂的LaMnO3阴极以及掺杂的LaCrO3连接材料等。     

一种新的湿排粉煤灰活化处理方法

纳米技术和纳米材料的科学价值已逐渐被人们所认识，利用纳米技术对粉煤灰表面进行化学处理，使粉煤灰表面形成纳米、微米尺寸的活化腐蚀层。采用这种方法可大大提高粉煤灰水泥早期强度和后期强度，提高粉煤灰掺量。经处理的活化粉煤灰具有早强、减水效果，可用于砼掺和料，掺量可达30％～50％，具有较大的应用和推广价值。     

La1-xSrxCo0.2Fe0.8O3-δ阴极材料的导电机理研究

La1-xSrxCo1-yFeyO3-δ系(LSCF)钙钛矿结构复合氧化物是一类性能优异的离子-电子混合导体,同时具有良好的化学稳定性和催化活性,是很好的中低温固体氧化物燃料电池(SOFC)阴极材料的候选材料.本文测试了制备出的La1-xSrxCo0.2Fe0.8O3-δ(x=0.1～0.5)系材料电导率并探讨了它们的离子导电、电子导电的微观机制,指出除了小极化子导电机制外,还可能有以下几种机理共同作用:1)热激发引起Co3 离子的电荷歧化;2)高温下氧空位生成导致的离子补偿;3)Fe4 较Co4 优先进行电子补偿.     

中低温固体氧化物燃料电池陶瓷阴极材料

综述了中低温固体氧化物燃料电池（SOFC）陶瓷阴极材料的研究和发展动态，这些陶瓷材料包括焦绿石结构的A2Ru2O7-δ陶瓷，Ag-YDB(Y2O3dopedBi2O3)复合陶瓷以及具有钙钛矿结构的La1-xSrxCo1-yFeyO3(LSCF)型陶瓷。     

湿排粉煤灰的活化及其应用研究

利用纳米技术及纳米制备方法处理粉煤灰, 使其表面形成纳米、微米尺寸的活化腐蚀层,或利用化学反应形成纳米、微米尺寸的活化沉淀物, 可大大提高粉煤灰水泥的早期强度和后期强度及粉煤灰掺量。经处理的系列活化粉煤灰具有早强、减水效果, 可用作混凝土掺和料, 掺量达30%~50%, 具有一定的应用和推广价值。     

钙钛矿型复合氧化物La1-xSrxFe1-yCoyO3的制备与应用

综述了钙钛矿型复合氧化物La1-xSrxFe1-7CoyO3的制备方法，介绍了其结构，性能特征及其主要应用前景。