[XRD and Raman spectroscopic comparative study on phase transformation of gamma-Al2O3 at high temperature].

The phase transformation of gamma-Al2O3 at high temperature was characterized by XRD and Raman techniques. Raman results show that under the excitation at 632.8 nm, the Raman shift bands at 1175 and 1241 cm(-1) and the other two bands at 1370 and 1 400 cm(-1) are attributed to the Cr3+ and (or) Fe3+ fluorescence bands in theta-Al2 03 and alpha-Al2O3 environments respectively. Compared with XRD measurements, it is more sensitive to use these two groups of Raman bands to estimate the phase formation and transformation of theta-Al2O3 and alpha-Al2O3. Therefore, Raman spectroscopy can deduce the high temperature phase transformation effectively. Experiments results show that gamma-Al2O3 starts to transform to theta-Al2O3 and alpha-Al2O3 synchronously at 800 degrees C, but the nature of the sample determines the final temperature of transforming to alpha-Al2O3.