Electrical conductivity of partially ion exchanged Sr and Ba β-alumina single crystals determined by a.c. impedance spectroscopy

Abstract

Ion exchange experiment was conducted on SrMgAl 10O 17 and BaMAlg 10O 17 β-alumina single crystals, which were prepared by a floating zone method. The ion exchange ratio of Na + for Sr 2+ in SrMgAl 10O 17 was 55%, and that of Na + for Ba 2+ in BaMgAl 10O 17 was 20%. The electrical conductivity ( σ), parallel ( σ //) and perpendicular ( σ ⊥) to the conduction plane, was increased by several orders of magnitude after the ion exchange. The ion exchanged specimens showed greater anisotropy of electrical conductivity than the as-grown ones. Nonlinear relationship of log ( σT) vs. 1/ T was observed for the ion exchanged Sr β-alumina single crystal. Cations located in the conduction plane were proposed as the transport carrier through the spinel block and screw dislocation defect may be responsible for that conduction.