The Effect of Calcination Temperature on Crystal Structure of (Al,Cr)2O3 Solid Solution

Abstract

(Al,Cr)₂O₃ solid solutions were synthesized using aluminium oxide (Al₂O₃) and chromium oxide (Cr₂O₃) as the starting materials. These two oxide powders were mixed at 1:1 mole ratio using ball mill. Then the mixture was dried and calcined for 2 hours at various temperatures of 1,500 °C, 1,600 °C and 1,700 °C. The structures of the prepared powders were investigated by X-ray diffraction (XRD) technique. The XRD result showed that (Cr_1-x, Al_x)₂O₃ presented as a new phase in the calcined powders for all temperatures. The XRD pattern illustrated intensity of (Cr_1-xAl_x)₂O₃ peaks slightly increased and shifted to Al₂O₃ peaks when the calcination temperature increase, while intensity of Al₂O₃ peaks gradually decreased. From this result, it can be implied that Cr³⁺ in Cr₂O₃ rhombohedral structure was gradually substituted by Al³⁺ at high temperature. However, the completed reaction was clearly shown at 1,700^oC. In addition lattice parameters (d-spacing 311 plane. a and c) were inversing with the calcined temperature.