Study of the process of mechanochemical activation to obtain aurivillius oxides with n=1

Mechanochemical activation has been successfully used as an alternative method for producing Aurivillius oxides with n = 1, like Bi2MoO6, Bi2VO5.5, and Bi2VO2. The analysis of the mechanoactivated materials by SEM and TEM allows the study of the mechanisms involved in the process of mechanical activation and the occurrence of mechanosynthesis. It is observed that if the amorphization of all the starting oxides is achieved during the process, evidence of mechanosynthesis, i.e., the synthesis of the final product, is found in the resulting particles. The phases obtained either cannot be synthezised by the traditional solidstate reactions or show special characteristics, all of which confirms that the mechanisms of phase formation involved in the mechanical and the thermal activations are different. Further annealing at higher temperatures makes all these structures go back to the phases traditionally obtained by thermal activation. (C) 2001 Academic Press.