Rapid fabrication of Ba1–xSrxTiO3 ceramics via reactive flash sintering

Abstract

Ba_1–xSr_xTiO₃ (BST) ceramics are promising dielectric materials. However, their fabrication is usually laborious, requiring long preparation stages and high temperatures, which are not favorable for tuning the grain size and dielectric properties. In this study, (Ba_1–xSr_x)TiO₃ (x = 0.1, 0.3, 0.5) ceramics were produced via reactive flash sintering (RFS) of a mixture of BaCO₃, SrCO₃ and TiO₂ powders at 900 °C and relatively short times (15–90 s). The electric field (E-field) with a strength of 400 V/cm and the current densities of 25–75 mA mm⁻² were applied during RFS. Once the Sr²⁺ content increased, the incubation time for the RFS decreased, suggesting that the addition of Sr²⁺ facilitated the RFS process. At the RFS time above 15 s, a single-phase Ba_0.6Sr_0.4TiO₃ perovskite structure was formed. When the time and the applied current density increased, both the densities and grain sizes within the ceramics increased. This increased the real part (ε’) of the complex permittivity compared to that of the conventionally sintered (CS) ceramic. Moreover, the enhancement of mass transport by E-field-induced oxygen vacancies was considered the predominant mechanism of RFS in the production of BST ceramics.