γ-Al2O3高温相变的XRD和Raman光谱比较研究

采用XRD和Raman光谱研究了γ-Al2O3的高温相变.Raman结果表明,位于1 175,1 241 cm-1和1 370,1 400 cm-1的2组谱峰是杂质Fe3 和(或)Cr3 在θ-Al2O3和α-Al2O3环境中产生的荧光光谱,用这2组峰来指认θ-Al2O3和α-Al2O3物相比XRD更灵敏.因此,Raman技术能高灵敏地表征γ-Al2O3的高温相变过程.结果表明γ-Al2O3从800 ℃开始发生相变,γ-Al2O3同时向θ-Al2O3和α-Al2O3转变,随着温度的升高最终完全转变成α-Al2O3.相变温度与样品本身有关.

XRD and Raman Spectroscopic Comparative Study on Phase Transformation of γ-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.