Fine-grained barium stannate titanate ceramics obtained by current-controlled flash sintering for energy-storage applications

Abstract

Current-controlled flash sintering provided an energy-efficient route to refine the microstructure of BaTi0.85 Sn0.15O3 ceramics. Full densification was achieved within minutes at 1200 ºC, yielding a fine-grained bimodal microstructure with mean grain sizes of ˜1.4um and ˜4.3 um, in contrast to the coarse grains (˜ 90 um) produced by conventional sintering after 3 h at 1350 ºC. Despite this substantial grain refinement, the flash-sintered ceramic preserved a recoverable energy density (˜46 mJ cm-3) and an efficiency (˜90%) comparable to those of the conventionally sintered specimen. Impedance spectroscopy revealed distinct electrical heterogeneity for each microstructure, yet these differences had no detrimental effect on the energy-storage performance; notably, the flash-sintered sample exhibited a higher electrical breakdown strength, highlighting the benefits of grain refinement. These findings demonstrate that current-controlled flash sintering enables the fabrication of dense, fine-grained ceramics without compromising functional properties, offering a promising route for microstructure engineering in lead-free dielectric energy-storage materials.

S. L-B. thanks Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR), Catalonia, Spain, for the FI-SDUR contract (2020 FISDU 00489). J.D.S.G. acknowledges the National Council of Scientific and Technological Development (CNPq), Brazil grants 309494/2022-2 and 408662/2023-9, the Minas Gerais Research Foundation (FAPEMIG), Brazil grants PPM-00661-16 and APQ-02875-18, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001, and the MCTI/FINEP/FNDCT, Brazil (grant 0966/24 #01.25.0086.00) for financial support.

Peer Reviewed

Postprint (published version)