Electrical conductivity of partially ion exchanged Sr and Ba β-alumina single crystals determined by a.c. impedance spectroscopy
An Yu Zhanga, b, , , Takaya Akashia, c, Bo Ping Zhanga and Takashi Gotoa
aInstitute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan bSchool of Material Science and Engineering, Beihang University, 37 Xueyuan Road, Haidian District, Beijing 100083, China cGraduate School of Engineering, Hokkaido University, West-8 North-13 Kitaku, Sapporo 060-8628, Japan
Received 29 December 2005; accepted 31 January 2006. Available online 20 February 2006.
Ion exchange experiment was conducted on SrMgAl10O17 and BaMAlg10O17 β-alumina single crystals, which were prepared by a floating zone method. The ion exchange ratio of Na+ for Sr2+ in SrMgAl10O17 was 55%, and that of Na+ for Ba2+ in BaMgAl10O17 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.
Keywords: Ion exchange; β-Alumina single crystal; Electrical conductivity; a.c. impedance spectroscopy