Non-stoichiometric Ba β-alumina single crystals, Ba1-0.25xMg1-xAl10+xO17+0.25x (x = 0 to 1), were prepared in the BaO–MgO–Al2O3 system by using a float-zone method. The single crystals were cleaved parallel to a (001) plane. The electrical conductivity parallel to the cleavage plane (σ||) was 10 to 20 times greater than that perpendicular to the cleavage plane (σ). The σ|| and σ had the maximum at around x = 0.5. The activation energy of σ, 240 to 270kJ/mol, was slightly greater than that of σ||, 170 to 190kJ/mol. The σ|| was almost independent of O partial pressure (PO2), while σ showed a PO2-1/6 dependence in a low PO2 region of PO2 = 10-4 to 10-13Pa.

Electrical Conductivity of Nonstoichiometric Ba β-Alumina Single Crystals Prepared by a Floating Zone Method. A.Y.Zhang, T.Akashi, T.Goto: Solid State Ionics, 2004, 166[1-2], 77-82