Design and Optimization of Gradient Interface of p-Type Ba0.3In0.3FeCo3Sb12/Bi0.48Sb1.52Te3 Thermoelectric Materials
A series of p-type Ba0.3In0.3FeCo3Sb12/Bi0.48Sb1.52Te3 (FS/BT) thermoelectric (TE) materials containing one gradient layer (1GL) with FS/BT volume ratio of 5:5, 3GLs-I with 7:3–5:5–3:7, 3GLs-II with 3:7–5:5–7:3, and 3GLs-III with 3:7–5:5–3:7 from FS to BT were fabricated by a two-step spark plasma sintering method. The interface structure and mechanical properties of the p-type FS/BT TE materials were investigated in this work. Designing the GLs at the interface of FS and BT bulk TE materials can effectively relax the thermal stress induced by the large difference in thermal expansion coefficient and eliminate the macroscopic cracks that occur in FS/BT TE materials with no GL, hence resulting in a remarkable enhancement in the interface mechanical properties of the FS/BT TE materials with the GLs. The optimized gradient interface of the FS/BT TE materials is 3GLs-II with FS/BT volume ratio of 3:7–5:5–7:3. The highest flexural strength of the 3GLs-II sample reached 13.68 MPa, increased by 116%.