Ionic conductivity in Na +, K +, and Ag + β″-alumina

• Published in: Journal of solid state chemistry Vol. 33; no. 3; pp. 385 - 390
• Main Authors: Briant, J.L., Farrington, G.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.1980
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/0022-4596(80)90161-9

This paper presents measurements of the ionic conductivity in single crystals of β″-alumina (0.84 M 2O · 0.67 MgO · 5.2 Al 2O 3, M = Na, K, Ag). Single crystals of sodium β″-alumina were grown from a melt of Na 2O, MgO, and Al 2O 3 at 1660 to 1730°C. Selected crystals were converted to the other isomorphs by ion exchange. The conductivity of sodium β″-alumina varies from 0.18 to 0.01 (ohm · cm) −1 at 25°C depending upon crystal growth conditions. Potassium β″-alumina has the unusually high room temperature conductivity of 0.13 (ohm · cm) −1. Silver β″-alumina has a slightly lower conductivity, 4 × 10 −3 (ohm · cm) −1 at 25°C. The activation energies of sodium and potassium β″-alumina decrease with increasing temperature, while that of silver β″-alumina is constant from −80 to 450°C.