Optimized mixed ionic–electronic conductivity in two-phase ceria–zirconia composite with cobalt oxide and Na2CO3 as suitable additives
Optimized mixed ionic–electronic conductivity in two-phase ceria–zirconia composite with cobalt oxide and Na2CO3 as suitable additives
复制标题
DOI：
10.1039/c5ta09832g
复制
发表时间：
2016-03
影响因子：
--
通讯作者：
Aditya Maheshwari;H. Wiemhöfer
中科院分区：
文献类型：
--
作者：
Aditya Maheshwari;H. Wiemhöfer
研究了由钽掺杂氧化铈（TDC）和氧化钇掺杂氧化锆（YSZ）组成的复合膜，旨在优化混合离子-电子传导。一个特别的兴趣是找到合适的添加剂，最大限度地减少通常高的界面电阻的电子和氧离子传输在氧化铈-氧化锆两相界面。两种类型的添加剂进行了研究：（a）CoO，以提高电子导电性和（B）Na 2 CO 3，SrCO 3和BaCO 3，以实现在晶界和通过晶界的离子传输的有利影响。与不含氧化钴的复合材料相比，1.6wt%CoO（1mol%）使电子电导率增加了十倍。关于离子传输，SrCO 3和BaCO 3没有表现出有利的影响，而添加20wt%Na2CO3引起了三个数量级的离子电导率的明显增加。最后，在CoO掺杂量为1.6wt%、Na 2CO 3添加量为14.3wt%的样品中，CoO和Na 2CO 3的组合效果得到了优化，其电导率值比无添加剂的TDC-YSZ复合材料高近1000倍。该样品的离子和电子电导率相对较高，足以获得良好的MIEC复合膜。给出了一个一致的模型来解释的传输机制，支持连续的氧离子传输通过两个YSZ晶粒之间的Na 2CO 3夹层。它基于钠离子迁移率、O2−离子交换以及Na 2 O和CO2的可逆形成，其方式与相应的基于Na 2CO 3的CO2传感器相同。
Composite membranes consisting of tantalum doped ceria (TDC) and yttria doped zirconia (YSZ) were investigated, aiming at an optimized mixed ionic–electronic conduction. A particular interest was to find suitable additives that minimize the usually high interface resistance for both electron and oxygen ion transport at ceria–zirconia two phase interfaces. Two types of additives were investigated: (a) CoO, to improve the electronic conduction and (b) Na2CO3, SrCO3 and BaCO3, to achieve a favorable influence on the ionic transport at and through grain boundaries. As compared to cobalt oxide free composites, ∼1.6 wt% CoO (1 mol%) increased the electronic conductivity by one decade. Regarding the ion transport, SrCO3 and BaCO3 exhibited no favorable influence, whereas the addition of 20 wt% Na2CO3 caused a clear increase in ionic conductivity by three orders of magnitude. The combined effect of cobalt oxide and Na2CO3 addition was optimized finally in a sample with ∼1.6 wt% CoO doping and ∼14.3 wt% Na2CO3 addition which showed a conductivity value nearly 1000 times higher than the additive free TDC–YSZ composite. Ionic and electronic conductivities for this sample were comparatively high and enough to achieve a good MIEC composite membrane. A consistent model is given to explain the transport mechanism which supports a continuous oxygen ion transport through a Na2CO3 interlayers between two YSZ grains. It is based on sodium ion mobility, exchange of O2− ions and reversible formation of Na2O and CO2 in the same way as known from corresponding Na2CO3 based CO2 sensors.