Low-Temperature Fabrication of Plate-like α-Al 2 O 3 with Less NH 4 F Additive.

Fluorinated compounds are effective mineralization agents for the fabrication of plate-like α-Al 2 O 3 . However, in the preparation of plate-like α-Al 2 O 3 , it is still an extremely challenging task to reduce the content of fluoride while ensuring a low synthesis temperature. Herein, oxalic acid and NH 4 F are proposed for the first time as additives in the preparation of plate-like α-Al 2 O 3 . The results showed that plate-like α-Al 2 O 3 can be synthesized at a low temperature of 850 °C with the synergistic effect of oxalic acid and 1 wt.% NH 4 F. Additionally, the synergistic effect of oxalic acid and NH 4 F not only can reduce the conversion temperature of α-Al 2 O 3 but also can change the phase transition sequence.