Effects of Dislocations on the Oxygen Ionic Conduction in Yttria Stabilized Zirconia

Abstract

Ionic conductivities of yttria-stabilized zirconia (YSZ) single crystals deformed at high-temperature were measured by the AC impedance method. A correlation between ionic conductivity and dislocation structures of deformed YSZ single crystals were investigated. Electrical conductivity measurements of the deformed YSZ crystals were performed for two different current directions of [1 1 10] and [ 1 1 1 11]. The [1 1 10] direction is parallel to edge dislocations introduced by the primary slip system, while the [ 1 1 1 11] direction is normal to the edge dislocation lines. Transmission electron microscopy observations showed that the dislocations due to the primary slip system of (001) [110] were mainly generated at the strain of around 1% strain, while the secondary slip systems, such as (1 1 1 1 1)[101] and (1 1 11)[011], were also activated at about 10% strain. It was found that the deformed samples with larger strains exhibited higher electrical conductivities irrespective of the measured current directions. However, the electrical conductivity along [ 1 1 1 11] was higher than that along [1 1 10], suggesting that mobility of oxygen ion is sensitive to the dislocation structures. From the activation energy for oxygen diffusion in the deformed samples, it was found that the oxygen migration enthalpy for deformed samples became smaller than that for undeformed samples, whereas the association enthalpy for the deformed samples became larger. The increase in the association enthalpy might be due to interaction between oxygen vacancies and dislocations. It is thus considered that oxygen vacancies concentrate around dislocations, and are able to move very quickly along the dislocation lines.

Termination chemistry-driven dislocation structure at SrTiO3/MgO heterointerfaces

“…48). In addition, as oxide nanocomposites are increasingly used in solid oxide fuel cells and oxygen separation membranes 7 , the TiO 2 -terminated interface can serve as a model system for assessing the role of pipe diffusion for conductivity, as observed in yttria-stabilized zirconia 49 . In contrast, the SrOterminated interface does not exhibit such behaviour, with vacancies concentrated in terraces separated by dislocations that act as barriers for migration.…”

Oxide Ceramics with High Density Dislocations and Their Properties

“…Therefore, the compression axis was slightly tilted to be the h112i direction, and it was selected as a compression axis. 14,15) In this case, although the compression axis is tilted by 55 against the {001} plane and its Schmidt factor is 0.47, the single slip is expected in the beginnings of deformation. In this study, the dislocation density and its arrangement were controlled by compression deformation tests systematically at various temperatures and at different strain rates.…”

“…Figure 7 shows the microstructure with strain amount of (a) 1% and (b) 10% in the case where deformation was made at the temperature of 1300 C at the strain rate of 8 Â 10 À6 s À1 , respectively. 14,15) The observations were made along the ½1 1 10 direction, in which the Fig. 7 Bright field images of the dislocation structures for the specimens deformed up to (a) 1% and (b) 10% strain with the incident beam parallel to the ½1 1 10 direction, which is parallel to the dislocation lines introduced by primary slip.…”

“…As model systems, we selected insulating sapphire and Y 2 O 3 Stabilized Zirconia (YSZ) single crystal, expected as an ion conductor, respectively to introduce dislocations by high temperature plastic deformation. [9][10][11][12][13][14][15][16][17][18][19][20] …”

Columnar grain boundary coherence in yttria-stabilized zirconia thin film: effects on ionic conductivity

“…22),23) Otsuka et al reported that the dislocation line also acts as a rapid diffusion path. 24), 25) The impurity segregation along grain boundaries also affects the YSZ properties.…”