Highly oriented β″-alumina ceramics with excellent ionic conductivity and mechanical performance obtained by spark plasma sintering technique

β″-Alumina ceramics are widely used in sodium batteries thanks to their excellent Na⁺ ion conductivity and high mechanical strength. In this study, highly oriented β″-alumina ceramics with good electrical conductivity and high mechanical strength were fabricated using spark plasma sintering approach at a lower temperature (1300 °C). Furthermore, X-ray diffraction analysis showed that degrees of orientation of rod-like and flaky-like β″-alumina ceramics, for which one-dimensional rod-like and two-dimensional flaky-like boehmite (γ-AlOOH) were used as respective presintered precursors, were as high as 0.74 and 0.46, respectively. The electrical conductivity of rod-like β″-alumina ceramics was 1.83 × 10⁻¹ S cm⁻¹ at 350 °C in the direction perpendicular to the pressure direction, which implies the superior conductivity. Bending strengths of both rod-like and flaky-like β″-alumina ceramics were up to 250 MPa. The superior ionic conductivity, together with the excellent strength, demonstrates that the highly oriented structure is beneficial to ion transport and strength improvement and therefore generates ceramics with excellent mechanical strength and ionic conductivity.