Preparation and Characterization of Ni/Bi 0.5 Sb 1.5 Te 3 Heterogeneous Multilayered Thermoelectric Materials

It is difficult to achieve coordinated optimization in thermoelectric materials due to the strong coupling between the electrical and thermal transport properties. However, interface effects, especially those caused by heterogeneous interfaces, are promising to overcome this challenge. In this work, the Ni/Bi 0.5 Sb 1.5 Te 3 (BST) heterogeneous multilayer structure thermoelectric materials were fabricated by the combination of vacuum evaporation deposition and spark plasma sintering. The influence of Ni layer on the phase composition, microstructure and thermoelectric performance along the different directions (0°, 30°, 60° and 90°, the angles between the performance measurement direction and the Ni layer) of Ni/BST materials were systematically investigated. The microstructural analysis indicates that the distinct heterogeneous interfaces were firmly bonded, and the interface reaction layer was composed of Ni and Te. As compared with the matrix, the electrical conductivity and Seebeck coefficient of the Ni/BST heterogeneous multilayer thermoelectric materials increased, and the thermal conductivity slightly reduced. For Ni/BST90° sample, the maximum ZT value of 1.05 was achieved at 370 K, increased by 19.1% compared with the BST90°. Our work demonstrates that the electron and phonon transport properties can be simultaneously optimized by introducing the ordered heterogeneous interfaces.