Electrocaloric effects in spark plasma sintered Ba0.7Sr0.3TiO3-based ceramics: Effects of domain sizes and phase constitution

Abstract The crystal structures, domain structures, dielectric strengths and electrocaloric effects of spark plasma sintered Ba 0.7 Sr 0.3 TiO 3 and Ba 0.7 Sr 0.3 Ti 0.997 Mn 0.003 O 3 ceramics have been investigated. The densification can be enhanced by the spark plasma sintering (SPS) process without obvious grain growth, where the fine ferroelectric domain structures are obtained. The content of tetragonal phase in Ba 0.7 Sr 0.3 TiO 3 ceramics prepared by the SPS process is lower than that in the counterpart prepared by the conventionally sintering process, but it will increase again by partially substituting titanium with 0.3 mol% manganese ions. The dielectric strength can be significantly enhanced by the spark plasma sintering process, which can be improved further by Mn-substitution, and consequently the electrocaloric temperature change, Δ T , increases. Meanwhile, the electrocaloric strength has been enhanced by the spark plasma sintering process, which should be attributed to combined effects of domain wall density the content of ferroelectric phase in the present ceramics.