Ion conduction in nanoscale yttria-stabilized zirconia fabricated by atomic layer deposition with various doping rates J. Vac. Sci. Technol. A 31, 01A107 (2013); 10.1116/1.4755921Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconiaThe ionic conductivity of yttria-stabilized zirconia ͑YSZ͒ single crystals (10 mol %Y 2 O 3 -ZrO 2 ) was enhanced by introducing high density of dislocations. YSZ single crystals were systematically deformed by compression tests at 1300°C, and their electrical conductivity was measured by an AC impedance method. It was confirmed that a great number of dislocations were introduced in YSZ by the high-temperature deformation, and the density reached up to more than 8ϫ10 12 m Ϫ2 , depending on the compression strains imposed on the samples. The electrical conductivity of the deformed samples was found to be larger than that of undeformed samples. Furthermore, samples with larger strains exhibited higher electrical conductivity, which indicates that dislocations generated by the plastic deformation play an important role to enhance the ionic conductivity of YSZ.

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.

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