Study of crystallisation of Al2O3-Fe2O3 gels by Mossbauer spectroscopy

Boehmite derived alumina gels seeded (5 wt.%) with alpha -Al2O3, alpha -Fe2 O3 and Fe(NO3)(3), were examined by Mossbauer spectroscopy. Feric oxide org inated from Fe(NO3)(3) was identified in defect alumina phases in two high disperse form as solid solution gamma-(Al, Fe)(2)O-3 and substituted hemati te particles (alpha-(Fe, Al)(2)O-3 similar to 6 nm). Dispersed Fe3+ ions re duce temperature of the crystallisation of alpha -Al2O3 (solution (Al, Fe2O 3)) much more significantly than particulate seeds. Enhanced transformation has been attributed to solution effect of dispersed Fe3+ ions resulting in transparent ceramics sintered below 1300 degreesC.