Synthesis of plate‐like α ‐alumina crystals by solid state reaction of fir immersed with slurry mixture of gibbsite and non‐fluorine morphological modifiers

Solid state reaction without fluorine addition was employed to synthesise plate‐like α ‐alumina. Platelets of α ‐alumina with non‐uniform thickness were obtained using slurry mixture (SM) comprised of gibbsite and morphological modifiers as starting materials. In comparison, α ‐alumina crystals were fabricated with a plate‐like shape with uniform thickness after calcination of fir immersed with SM (FISM). The activation energies of phase transformation from γ ‐alumina to α ‐alumina for SM and FISM are determined by the Kissinger method as 109.8 and 132.9 kJ/mol, respectively. These results indicate the rearrangement of atomic stacking during transformation is accomplished with a relatively slow rate in an open space after the decomposition of fir template. The present study demonstrates a facile method to fabricate α ‐alumina platelets with extensive applications.