Thermoelectric properties for P-type (Bi2Te3)0.2(Sb2Te3)0.8 alloys fabricated by shear extrusion
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P-type (Bi2Te3)0.2(Sb2Te3)0.8 compounds were synthesized via bulk mechanical alloying (BMA), and subsequently prepared by a shear extrusion process in order to create the developed texture. The shear extrusion process improved the preferred orientation factor of the anisotropic crystallographic structure. It was found by an electron backscattered diffraction pattern (EBSP) analysis that approximately 90% of the crystallographic orientations for shear-extruded sample are aligned in the range deviated from 60° to 90° from the c-axis. The electric resistivity is well controlled at 1.008×10−5Ωm, which is nearly equal to that of the unidirectionally grown sample. The maximum figure of merit for the (Bi2Te3)0.2(Sb2Te3)0.8 alloy was found to be z=3.03×10−3K−1. The bending strength of the material produced is also improved to 120 MPa, six times larger than that of the unidirectionally grown sample.
Keywordsp-type shear extrusion anisotropy electron backscattered diffraction patterns (EBSP) crystallographic orientation
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