氧化还原可逆Nb2TiO7复合阴极电解池高温水蒸气电解研究

系统地研究Nb₂TiO₇与Nb_1.33Ti_0.67O₄材料相互转变的氧化还原循环可逆性能,同时研究Nb2TiO7和Nb_1.33Ti_0.67O₄样品随温度和氧分压变化的电导率,并与复合电极对称电池和电解池的电化学性能相关联. 在830 oC下,对Nb_1.33Ti_0.67O₄复合电极电解池进行水蒸气的电解研究测试. 电流电压曲线和电解池短期性能测试表明在低电压下主要为电极的还原和活化过程;而在高电压下主要为水蒸气的电解. 当3%H₂O/Ar/4%H_{2气体通入阴极时电解池水蒸气电解的法拉第效率为98.9%;而当通入气体转换为3%H2O/Ar时效率为89%.}     

反应扩散模型在图灵斑图中的应用及数值模拟

反应扩散方程模型常被用于描述生物学中斑图的形成.从反应扩散模型出发,理论推导得到GiererMeinhardt模型的斑图形成机理,解释了非线性常微分方程系统的稳定常数平衡态在加入扩散项后会发生失稳并产生图灵斑图的过程.通过计算该模型,得到图灵斑图产生的参数条件.数值方法中采用一类有效的高精度数值格式,即在空间离散条件下采用Chebyshev谱配置方法,在时间离散条件下采用紧致隐积分因子方法.该方法结合了谱方法和紧致隐积分因子方法的优点,具有精度高、稳定性好、存储量小等优点.数值模拟表明,在其他条件一定的情况下,系统控制参数κ取不同值对于斑图的产生具有重要的影响,数值结果验证了理论结果.     

镨掺杂对无钴钙钛矿型氧化物BaFeO3-δ电导率和透氧性能的影响

Among the perovskite-type oxides with symmetrical structure applied in oxygen permeable membranes,cubic phase structure is the most favorable for oxygen permeation.In order to stabilize the cubic perovskite structure of BaFeO_3-δ material at room temperature,iron was partially substituted by praseodymium.BaFe_1-yPr_yO_3-δ powders were synthesized by a solid state reaction method,and sintered samples were prepared from the synthesized BaFe_1-yPr_yO_3-δ powders.X-ray diffraction results reveal that the BaFe_1-yPr_yO_3-δ samples remain cubic structure at praseodymium substitution amount of y=0.05,0.075,0.1.Scanning electron microscope observation indicates that the sintered samples contain only a small amount of enclosed pores and the grain size of BaFe_1-yPr_yO_3-δ increase monotonically with the increase of the praseodymium doping amount,praseodymium doping promotes the grain size growth.Tests of electrical conductivity and oxygen permeation flux show that praseodymium doping improves the conduction properties of BaFe_1-yPr_yO_3-δ and BaFe_0.9Pr_0.1O_3-δ composition has an electrical conductivity of 6.5 S/cm and an oxygen permeation of 1.112 mL/(cm²·min) at 900 ℃,respectively.High temperature XRD investigation shows that the crystal structure of BaFe_0.975Pr_0.025O_3-δ membrane completely transform to cubic phase at 700 ℃.The present test results have shown that partially substitution of Fe by praseodymium in BaFeO₃ can stabilize the cubic structure and improve the properties.