Nonstoichiometric Ba β-alumina single crystals, Ba1 - 0.25xMg1 - xAl10 + xO17 + 0.25x (0 ≤ x ≤ 1), were prepared in the BaO-MgO-Al2O3 system by a floating 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 270 kJ/mol, was slightly greater than that of σ//, 170 to 190 kJ/mol. The σ// was almost independent of oxygen partial pressure (PO2), while σ⊥ showed a PO2-1/6 dependence in a low PO2 region of PO2 = 10-4 to 10 -13 Pa.
ASJC Scopus subject areas
- 化学 (全般)