Enhanced thermoelectric properties of Bi₂Sr₂Co₂O_y ceramics by dispersing B₂O₃ additive

In this study, ceramic samples of Bi₂Sr₂Co₂O_y + v wt% B₂O₃ (v = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized using the solid state reaction method, and the influence of B₂O₃ additive on their microstructure and thermoelectric properties were investigated. On one hand, the B₂O₃ additive acted as a sintering aid, enhancing carrier mobility. On the other hand, B₂O₃ dispersion served as a nano-second-phase, increasing hetero-interfaces and strengthen phonon scattering, thereby effectively suppressing lattice thermal conductivity. By dual optimization of both electric and thermal transport performance, the Bi₂Sr₂Co₂O_y + 0.3 wt% B₂O₃ sample achieved a high ZT value (thermoelectric figure of merit) of 0.31 at 923 K, which was improved by approximately 33% compared with the pristine Bi₂Sr₂Co₂O_y sample.