Department of Chemical and Biomolecular Engineering, National University of Singapore , BLK E5 02-02, 4 Engineering Drive 4, Singapore 117576, Singapore.
ACS Appl Mater Interfaces. 2013 Sep 25;5(18):9067-74. doi: 10.1021/am4023384. Epub 2013 Sep 11.
Compositing fluorite Ce0.8Gd0.2O2-δ (CGO) oxide with perovskite La0.4Ba0.6Fe0.8Zn0.2O3-δ (LBFZ) oxide leads to the formation of a minor interfacial BaCeO3 phase upon sintering at 1400 °C. This interfacial composition assures a gastight ceramic membrane with fine grain-boundary structure, in which the LBFZ phase exhibits an improved oxygen permeability over the pristine LBFZ membrane on the same volumetric basis. The presence of the BaCeO3 phase effectively preserves the structural integrity of the composition by limiting the interfacial diffusion of barium ions between LBFZ and CGO. In comparison, replacing CGO with Y0.08Zr0.92O2-δ in the system results in a substantially low oxygen flux due to an overwhelming interfacial diffusion and, consequently, a heavy degradation of LBFZ. Besides structural reinforcement, the high interface between LBFZ and CGO benefits oxygen transport, as is proven through variation of the oxygen partial pressure on the feed side of the membrane and operation temperature. Furthermore, the trade-off between LBFZ loading and interfacial diffusion yields an optimal CGO loading at 40 wt %, which exhibits an oxygen flux of 0.84 cm(3)/cm(2)·min at 950 °C. In summary, the minor interfacial binding between CGO and LBFZ grains is constructive in easing oxygen crossover in the phase boundary with the exception of maintaining membrane structural stability under oxygen permeation conditions.
将萤石 Ce0.8Gd0.2O2-δ（CGO）氧化物与钙钛矿 La0.4Ba0.6Fe0.8Zn0.2O3-δ（LBFZ）氧化物复合，在 1400°C 烧结时会形成少量的界面 BaCeO3 相。这种界面组成确保了具有细晶界结构的气密陶瓷膜，其中 LBFZ 相在相同体积基础上表现出比原始 LBFZ 膜更高的氧气透过率。BaCeO3 相的存在通过限制 LBFZ 和 CGO 之间钡离子的界面扩散，有效地保持了组成的结构完整性。相比之下，在该体系中用 Y0.08Zr0.92O2-δ 替代 CGO 会导致氧气通量大大降低，这是由于界面扩散的压倒性作用，从而导致 LBFZ 严重降解。除了结构增强外，LBFZ 和 CGO 之间的高界面有利于氧气传输，这可以通过改变膜进料侧的氧气分压和操作温度来证明。此外，LBFZ 负载和界面扩散之间的权衡关系在 40wt%时产生了最佳的 CGO 负载，在 950°C 时氧气通量为 0.84cm3/cm2·min。总之，CGO 和 LBFZ 晶粒之间的少量界面结合在缓解相界处的氧气跨越方面是有益的，除了在氧气渗透条件下保持膜结构稳定性之外。
