Formation of continuous series of solid solutions from powders prepared by hydrazine method: The system Cr2O3-Al2O3

Chromia (Cr2O3)/alumina (A12O3) solid solution (ss) powders have been prepared by the hydrazine method. As-prepared powders are classified into three groups: (i) amorphous below 25 mol% A12O3, (ii) mixtures of this and AIO (OH) gel(ss) between 25 and 80 mol% A12O3, and (iii) AIO(OH) gel(ss) above 80 mol% A12O3. Cr2O3 solid solutions crystallize at low temperatures from amorphous materials. The formation process leading to continuous series of solid solutions is examined. Cr2O3 (ss) powders prepared at a composition of Cr2O3Al2O3 = 8020 mol% have been characterized for particle size and shape. Individual particles tend toward a hexagonal morphology above 900 °C.