Tetragonality enhancement in BaTiO 3 by mechanical activation of the starting Ba CO 3 and TiO 2 powders: Characterization of the contribution of the mechanical activation and postmilling calcination phenomena

• Published in: International journal of applied ceramic technology 2018-11, Vol.15 (6), p.1518-1531
• Main Authors: Moghtada, Abdolmajid, Heidary Moghadam, Ali, Ashiri, Rouholah
• Format: Article
• Language: English
• ISSN: 1546-542X; 1744-7402
• DOI: 10.1111/ijac.13019

By‐products including unwanted phase formation and/or unreacted starting materials are normally seen in the outcome of solid‐state synthesis approaches used in the literature for powder processing of advanced materials; this drawback requires critical attention and must be addressed in the new synthesis pathways in order to obtain quality powder products. A high energy mechanical milling approach was developed in this work. Addressing the drawback, the starting materials were mechanically activated by a high energy ball mill before their mixing step. It was found that highly pure barium titanate nanopowders with high tetragonality character are obtained using the approach developed here. The work also characterized tetragonality, role of the mechanical activation and postmilling thermal treatment on structure, phase formation and morphology of the obtained powder products. It was found that the mechanical activation accelerates the kinetic of formation of barium titanate and enhances the purity and tetragonality of the final products. The mechanism behind this achievement and the related reaction pattern are disclosed in this work. In order to obtain highly pure tetragonal barium titanate, a calcination temperature of 1173 K (900°C) after 30 hours mechanical activation is necessary; if these requirements are not satisfied, the final powder product contains impure phases and/or unreacted starting materials. The results also indicated that the processing conditions result in enhancement of tetragonality character of the final powder products. It seems that the method developed here can be used as a generalized methodology for obtaining the quality highly pure monosized nanocrystals of the mixed oxides for assembling in nanotechnology.