Abstract: Because of industrial interest, techniques to prepare a thermally stabilized active alumina have been developed.Ionic probe has been widely used in the studying of structure and function on biomacromolecules.In this paper, the phase transition in alumina at differ-ent sintering temperatures was first studied by Eu³⁺ ion fluorescent probe.The XRD, FTIRand fluorescence spectra measurements show that γ-phase is dominated in alumina at below 1000℃; the mixed γ-and phases in the sample are produced at 1100 ℃;but α-phase in alumina is dominated at 1200 ℃.It is shown in FTIRspectra that the peak of Eu-Ostretching vibration increases dramatically at 1200 ℃ Meanwhile, fluorescence spectra in-dicate that the peak of 613 nm is weakned gradually whereas the peak of 617 nm is strength-ened in⁵D₀-⁷F₂ supersensitive transition of Eu³⁺ when the sintering temperature increases.However, the peak of ⁵D₀-⁷F₄ transition splits evidently at 1200 ℃ because of the decreasing of symmetry in Eu³⁺ coordination site.

Key words: Phase transition in alumina, Eu³⁺ ion probe, Fluorescence spectra