Fabrication of Anisotropically Structured P-Type and N-Type Bi-Te Thermoelectric Materials via New P/M Route

摘要

Bi-Te system has been widely used as a thermoelectric material with relatively high figure of merit from room temperature to 500 K. Higher qualification of thermoelectric and mechanical properties is required for cooling of high-power laser or VLSI's. Single crystalline materials are preferable to efficient power generation or cooling. Their strength is too low to be utilized in practice. Polycrystalline sintered materials have sufficient strength but much lower thermoelectricity than single crystals. A new PM route is proposed to fabricate the nano-structured p-type and n-type Bi-Te thermoelectric materials from the mixture of elemental granules via bulk mechanical alloying. As its secondary process, the shear extrusion process is used to make texture control in Bi-Te thermoelectric materials and to produce Bi-Te thermoelectric sheet with high power factor and high bending strength.