Structure and properties relationships of beta-Al2O3 electrolyte materials

Beta-Al2O3 electrolyte materials were synthesized by solid-state reaction method in this paper. The effect of different stabilizers on the β”-phase content of the beta-Al2O3 electrolyte and the structures of aluminum-oxide polyhedron were investigated by X-ray diffraction technology (XRD) and 27Al MAS NMR, and the relationship between the β” phase content and the amounts ratio of octahedron and tetrahedron (AAl(VI)/AAl(IV)) was summarized. The results showed that the β” phase was stable at high temperatures and the β” phase content increased with the temperature increasing by the addition of the stabilizers. Meanwhile, δAl(IV) and δAl(VI) moved towards down field, and AAl(VI)/AAl(IV) decreased with the β” phase content increasing. The Mg2+ stabilizer was better to improve the symmetry of Al(VI) than the Li+ stabilizer.

► The β” phase of beta-Al2O3 was stable in high temperature and the β” phase content increased with the sintering temperature increasing by the addition of the stabilizers.
► By using NMR, δAl(VI) and δAl(IV) of beta-Al2O3 moved towards down field in different systems with different stabilizers. Li+ and Mg2+ ions substituted the octahedron and tetrahedral Al3+ ions in the spinel blocks respectively, and Mg2+ stabilizer was more benefit to improve the symmetry of Al(VI) of the beta-Al2O3 than Li+ stabilizer.
► The amounts ratio of octahedron and tetrahedron (AAl(VI)/AAl(IV)) of beta-Al2O3 decreased with the β” phase content increasing.