Nanoscale effects on ion conductance of layer-by-layer structures of gadolinia-doped ceria and zirconia

Abstract

Layer-by-layer structures of gadolinia-doped ceria and zirconia have been synthesized on Al2O3(0001) using oxygen plasma-assisted molecular beam epitaxy. Oxygen ion conductivity greatly increased with an increasing number of layers compared to bulk polycrystalline yttria-stabilized zirconia and gadolinia-doped ceria electrolytes. The conductivity enhancement in this layered electrolyte is interesting, yet the exact cause for the enhancement remains unknown. For example, the space charge effects that are responsible for analogous conductivity increases in undoped layered halides are suppressed by the much shorter Debye screening length in layered oxides. Therefore, it appears that a combination of lattice strain and extended defects due to lattice mismatch between the heterogeneous structures may contribute to the enhancement of oxygen ionic conductivity in this layered oxide system.

Synthesis and characterization of Zr0.85Y0.15O1.925-La9.33Si6O26 composite electrolyte for application in SOFCs

“…The conductivities of the composite materials consisting of the doped ceria and lanthanum silicate could be enhanced obviously by a nanocomposite process [2]. The oxygen ionic conductivity of nano-structured layer-by-layer electrolytes composed of gadolinia-doped ceria and zirconia could be increased greatly [4]. In YSZ-SrTiO 3 epitaxial heterostructures, a high lateral oxygen ionic conductivity, showing up to eight orders of magnitude enhancement near room temperature, was reported [6].…”

“…The former is a complex work for that it is not easy to find a new suitable compound. The composite process and nano-technology were reported to be the effective ways to improve dramatically the oxygen-ionic conductivity [2][3][4][5][6][7][8][9]. The conductivities of the composite materials consisting of the doped ceria and lanthanum silicate could be enhanced obviously by a nanocomposite process [2].…”

Epitaxial superlattices of ionic conductor oxides

“…In fact, it has been reported that thin films made of alternated multilayers (at least about 30 u.c. each) of GDC and Zirconia showed a small enhancement in conductivity with respect to the parent materials [7]. This increase has been attributed to a combination of lattice strain and extended defects due to lattice mismatch between the heterogeneous structures.…”

Tensile Lattice Distortion Does Not Affect Oxygen Transport in Yttria-Stabilized Zirconia–CeO2 Heterointerfaces

“…In general, literature data are quite consistent concerning the increased oxygen-ion conductivity of interfaces showing a large dislocation density, 4,7,9 but whether the interfacial strain can play a significant role in enhancing the ionic conductivity is still quite a controversial issue.…”