Room-temperature anisotropic, thermoelectric, and electrical properties of n-type (Bi2Te3)90 (Sb2Te3)5 (Sb2Se3)5 and compensated p-type (Sb2Te3)72 (Bi2Te3)25 (Sb2Se3)3 semiconductor alloys

Abstract

The anisotropy ratios (parallel to the c axis versus perpendicular to the c axis) for the electrical resistivity, Seebeck coefficient, and thermal conductivity of horizontal Bridgman-grown n-type (Bi2Te3)90 (Sb2Te3)5 (Sb2Se3)5 and p-type (Sb2Te3)72 (Bi2Te3)25 (Sb2Se3)3 were measured at 300 K. The orientation having the largest thermoelectric figure of merit was perpendicular to the zone axis of the c planes (along the natural growth direction). For the n-type alloy, the maximum thermoelectric figure of merit was determined to be 3.2×10−3/K. For the p-type alloy, the maximum thermoelectric figure of merit was determined to be 3.6×10−3/K when compensated with tellurium only, and 3.8×10−3/K when compensated with both tellurium and iodine. These values represent a significant increase over previously reported p-type thermoelectric figure of merit values. Hall coefficient data coupled with Seebeck coefficient measurements suggest a difference in carrier transport phenomena caused by an increased compensation of holes in the p-type alloy without the deleterious precipitation of the tellurium-rich second phase.

Thermoelectric properties of highly grain-aligned and densified Co-based oxide ceramics

“…23,24 For the (Sb 2 Te 3 ) 72 (Bi 2 Te 3 ) 25 (Sb 2 Se 3 ) 3 semiconductor alloy crystallized in a structure similar to Bi 2 Te 3 , ab / c is 1.3. For the YBa 2 Cu 3 O x single crystal, which has a layered structure, the anisotropic ratio ab / c ( ab and c are the values measured in the ab plane and c-axis direction, respectively͒ is larger than 4.…”

Anisotropic Analysis of Nanocrystalline Bismuth Telluride Thin Films Treated by Homogeneous Electron Beam Irradiation

“…The thermoelectric performance of the Bi 2 Te 3 compound is characterized by its remarkable anisotropic behavior due to the high c-axis to a-axis length ratio of its crystal structure. 5,6) The thermoelectric properties of the material in the direction parallel to the basal plane are superior to those in the direction perpendicular to the plane (lateral plane).…”

Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi2Te3 nanoplate thin films by drop-casting technique

“…Because of this crystal structure, the lattice constant in the c-axis is approximately seven times larger than that in the a,b-axis. As a result, Bi 2 Te 3 exhibits a remarkable anisotropic behavior [11][12][13] and its electrical conductivity along the a,b-axis direction is approximately three times larger than that along the c-axis direction. 14) A nanoplate is an ideal shape for the Bi 2 Te 3 to exhibit its remarkable anisotropic behavior.…”