Combustion synthesis and spark plasma sintering processing of (1-x)Ba(Zr₀.₂Ti₀.₈)O₃-x(Ba₀.₇Ca₀.₃)TiO₃ ceramics

Abstract

Solution combustion synthesis (SCS) has proven to be one of the simplest and fastest methods, using inexpensive materials and resulting in homogeneous stoichiometry with nanometric particle sizes. The spark plasma sintering (SPS) method has been used to obtain high-density ceramic materials with excellent control of microstructure. This work reports the successful combination of these two techniques for the fabrication of the high-density lead-free ferroelectric system (1-x)Ba(Zr_₀.₂Ti_₀.₈)O_₃-x(Ba_₀.₇Ca_₀.₃)TiO_₃. The X-ray diffraction of the powder indicates the majority formation of the perovskite structure and other residual reaction products, indicating a reactive powder. The SPS method resulted in highly densified samples, reaching relative density values close to 99% with a single-phase perovskite structure. Rietveld refinement revealed the presence of at least two perovskite phases, independent of calcium concentration. Dielectric measurements showed anomalies in both the real and imaginary parts of the dielectric permittivity, which are typical of phase transitions and a low dielectric loss for all compositions. This study shows that the combined use of SCS and SPS technique can be a powerful protocol to produce dense, fine-grained lead-free ferroelectric ceramics at relatively low temperatures and in short time periods.