Characterization of the Aluminas Formed During the Thermal Decomposition of Boehmite by the Rietveld Refinement Method

Boehmite synthesized through a sol‐gel route from a nonconventional raw material, as an aluminum waste, was calcined at temperatures between 500 and 1500°C. Quantification of crystalline phases was performed by the Rietveld refinement of the XRD patterns. γ‐Al 2 O 3 is formed at 500°C, and up to 1000°C, is the dominant phase. At temperatures ranging from 1000 to 1400°C, it was observed the appearance of a four‐phase region. The complete transformation into α‐Al 2 O 3 lasts until 12 h at 1400°C or at higher temperatures. The presence of an amorphous phase in calcined samples was confined by direct comparison with a standard of pure α‐Al 2 O 3 .