Thermoelectric properties of p-type Bi0.5Sb1.5Te3 for solid-state cooling devices

Understanding Bulk Defects in Topological Insulators from Nuclear‐Spin Interactions

“…[56] Another interesting feature we observe with all these TIs is that the linewidth of the shoulder peak decreases with increasing temperature, as would be expected due the motional narrowing of the lineshapes accompanied with a lack of annealing of the native defects at higher temperatures. [54,55,[58][59][60][61]68] Dislocations, strains and vacancies in the lattice can also enhance the observed line broadening, e.g., due to the substitution of Sb or S in the Bi 2 Te 3 matrix, especially in the case of the solid-solution Bi 0.5 Sb 1.5 Te 3 [10,17,24,26,28,33,35] and Bi 2 Te 2 S (a phase separated material). [5,6,71,72] 125 Te spin-lattice relaxation in materials which are dominated by structural defects is best described with a stretched exponential model (Kohlrausch function) [54,55,57,59,61,60,73] 𝑀…”

“…[7][8][9][10][11][20][21][22][26][27][28][29][30][31][32] These binary chalcogenides have been extensively studied due to their large thermo-electric power and applications as solid state power generators and refrigerators (Peltier, Seebeck and Thomson devices). [20][21][22][26][27][28][29] Recently, an effort aimed at improving the TE efficiency (figure of merit parameter, ZT) concluded that Bi 2 Te 3 -Sb 2 Te 3 solid solutions yield improved TE materials, according to the ZT parameter, which is maximized in the case of Bi 0.5 Sb 1.5 Te 3 [7,[17][18][19][20][24][25][26][27][28][29] Other ternary telluride compounds in the same class as these layered materials, Bi 2 Te 2 Se and Bi 2 Te 2 S, have shown the potential of tuning and enhancing transport properties. [1][2][3][4][5][6]30,32] The discovery of topological insulators has changed the way we look at chalcogenides.…”

“…The Te(2) sites refer to the outer planes of the quintuples which are exposed to the van der Waals gaps and host the topological surface states. [6][7][8][9][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The type of conduction in the Tetradymite family of TIs is strongly related to the type of structural defects present (anion vacancies or antisite). [1][2][3][4][5][6][7][8][9][10][11][12][13][14]16,22,25,28,32,35] Bi 2 Te 3 crystals grown from stoichiometric melts are p-type due to the presence of large number of Bi Te antisite defects.…”

“…[6][7][8][9][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The type of conduction in the Tetradymite family of TIs is strongly related to the type of structural defects present (anion vacancies or antisite). [1][2][3][4][5][6][7][8][9][10][11][12][13][14]16,22,25,28,32,35] Bi 2 Te 3 crystals grown from stoichiometric melts are p-type due to the presence of large number of Bi Te antisite defects. The type of conduction may be adjusted through fine tuning of the non-stoichiometry of the Bi/Te ratio, i.e., to dope the system by generating antisite defects of Bi Te (p-type) or Te Bi (n-type [18] ).…”