Enhanced thermoelectric properties of Bi2Sr2Co2Oy ceramics by dispersing B2O3 additive

In this study, ceramic samples of Bi 2 Sr 2 Co 2 O y  +  v wt% B 2 O 3 ( v  = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized using the solid state reaction method, and the influence of B 2 O 3 additive on their microstructure and thermoelectric properties were investigated. On one hand, the B 2 O 3 additive acted as a sintering aid, enhancing carrier mobility. On the other hand, B 2 O 3 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 Bi 2 Sr 2 Co 2 O y  + 0.3 wt% B 2 O 3 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 Bi 2 Sr 2 Co 2 O y sample.