Abstract: Lithium and magnesium co-stabilized β/β’’-Al₂O₃ films were fabricated by the reaction between the spinel-α-Al₂O₃
composite substrate and the vapour of Li₂O and Na₂O. The experimental results show that temperature is the main factor determining the forming
rate of the β/β’’-Al₂O₃ phases which cannot be obtained when the reaction taking place at below 1100℃. Dispersive spinel in the substrate can improve effectively the formation of β/β’’-Al₂O₃ phases even at
lower temperatures. The films obtained on composite substrate exhibit favorable electrical properties which are comparable to that of
β/β’’-Al₂O₃ ceramics, although a little spinel remained in the film to some extent reduce the ionic conductivity and at the same time
increase the activation energy of the film.

Key words: β/β’’-Al₂O₃, spinel, film, ionic conductivity