• Feldhoff, Armin
• Cano, Giamper Escobar
• Breidenstein, Bernd
• Riebesehl, Fabian
• Zhao, Zhijun
• Stölting, Oliver

Abstract

<jats:p>Due to its high chemical and thermal stability in CO<jats:sub>2</jats:sub> atmosphere and its anisotropic crystal structure, the Ruddlesden-Popper phase La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>has attracted considerable attention in the research field of oxygen-transporting membranes. The anisotropic properties of La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>can be exploited in textured polycrystalline membranes to control the oxygen diffusion through this material. To fabricate textured La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub> membranes, powder mixtures consisting of fine-grained equiaxial La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>matrix particles and large plate-like La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>template particles in different mass ratios were uniaxially pressed and then sintered in air. For this purpose, the anisotropic template particles were synthesized by molten-flux method using NaOH as flux [1]. In the powder mixture, the La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>template particles can be aligned perpendicular or parallel to the pressing direction, depending on the geometry of the pressing tool and the sample preparation. After the sintering process, textured La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>membranes were obtained,<jats:sub> </jats:sub>which was verified by measuring X-ray diffraction patterns and pole figures. Further X-ray diffraction measurements together with the calculation of the Lotgering orientation factor revealed that an increasing content of the template particles in the ceramic materials leads to a stronger texturing. Scanning electron microscopy micrographs show some individual plate-like<jats:italic><jats:sub> </jats:sub></jats:italic>La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub>grains well embedded in the matrix. Homogeneous distribution of lanthanum, nickel and oxygen in the ceramics was confirmed by energy-dispersive X-ray spectroscopy. Finally, the influence of the template particle content in the La<jats:sub>2</jats:sub>NiO<jats:sub>4+<jats:italic>δ</jats:italic></jats:sub> membranes on the oxygen permeation performance is discussed.</jats:p><jats:p> [1] Escobar Cano, G.; Brinkmann, Y.; Zhao, Z.; Kißling, P.A.; Feldhoff, A. Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La<jats:sub>2</jats:sub>NiO<jats:sub>4+</jats:sub><jats:italic><jats:sub>δ</jats:sub></jats:italic> Particles. <jats:italic>Crystals</jats:italic><jats:bold>2022</jats:bold>, <jats:italic>12</jats:italic>, 1346. https://doi.org/10.3390/cryst12101346</jats:p>

Topics

• impedance spectroscopy
• grain
• nickel
• phase
• scanning electron microscopy
• x-ray diffraction
• Oxygen
• anisotropic
• Lanthanum
• Energy-dispersive X-ray spectroscopy
• ceramic
• sintering
• aligned