From core–shell BaTiO3@MgO to nanostructured low dielectric loss ceramics by spark plasma sintering

Romain Berthelot, Brice Basly, Sonia Buffière, Jérôme Majimel, Geoffroy Chevallier, Alicia Weibel, Amélie Veillère, Laëtitia Etienne, U-Chan Chung, Graziella Goglio, Mario Maglione, Claude Estournès (+2 others)
2014 Journal of Materials Chemistry C  
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : Eprints ID : 13631 To link to this article : We report a quite general way to design materials with tailored properties by combining thermolysis and fast sintering approaches. Submicrometric-sized BaTiO 3 particles have been directly coated in a continuous nanocrystalline MgO
more » ... nanocrystalline MgO shell through a thermal decomposition process. The electron microscopy study has evidenced a shell composed of randomly oriented MgO nanocrystallites. The final nanostructured composite, made of sub-micrometric MgO and BaTiO 3 grains uniformly distributed, is obtained in situ during the SPS process. Such a rearrangement can be explained by the initial core-shell architecture, the weak cohesion of the MgO nanocrystallites and their soft plastic behavior under SPS conditions. The composite effect leads to significant modifications in both the dielectric properties and Curie-Weiss parameters compared to uncoated BaTiO 3 , especially a decrease and thermal stabilization of both the permittivity and the dielectric losses. We ascribe such changes to the stress generated during SPS through the extended interfaces between the two components. † Electronic supplementary information (ESI) available: Bright-eld TEM micrographs of BaTiO 3 -MgO particles obtained aer the washing sequence with cyclohexane only (Fig. S1 ). In situ dilatometry curves obtained during the SPS densication of the composite and pure BT ceramics (Fig. S2 ). An enlarged view of XRD powder patterns of the raw BT, sintered BT, as-prepared BT@MgO, and BT@MgO aer the heat treatment for 1 h at 600 C, and the sintered composite ceramic (Fig. S3 ). Temperature evolution of the inverse of permittivity (1/3 0 ) measured for the composite and BT SPS ceramics in addition to the corresponding Curie-Weiss tting in the paraelectric domain (Fig. S4) . See
doi:10.1039/c3tc31990c fatcat:jsbdfpfupbhrfidgysstqgqduy