Mechanism of the decrease of barriers for oxygen ionic conductivity in nanocrystalline ceramics

• Published in: Physica Status Solidi (b) 2007-02, Vol.244 (2), p.578-586
• Main Authors: Glinchuk, M. D., Bykov, P. I., Hilczer, B.
• Format: Article
• Language: English
• Subjects: 66.10.Ed; 66.30.Pa; Condensed matter: structure, mechanical and thermal properties; Diffusion in solids; Exact sciences and technology; Physics; Self-diffusion and ionic conduction in nonmetals; Transport properties of condensed matter (nonelectronic)
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.200642052

We calculate the influence of surface tension on the barriers for oxygen ionic conductivity in nanograin ceramics. Namely, we evaluate the activation energy for diffusion of oxygen ions via its vacancies. In our model, latter vacancies have been considered as dilatational centers. We have shown, that the activation energy decreases with nanoparticle size decreasing. We derive the distribution function of activation energy on the base of distribution of nanoparticle sizes. We obtain analytical expressions for dependence of ionic conductivity on the temperature and nanograin sizes. The obtained expressions describe the observed behaviour of oxygen conductivity in nanograin ceramics of ZrO2:16% Y pretty good. Our theoretical studies show that the surface tension in nanoparticles is indeed a physical mechanism responsible for the essential enhancement of the oxygen ionic conductivity observed in nanograin samples, where the main contribution to the conductivity goes from the region near the particle surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)