Atomic-scale chemical mapping of copper dopants in Bi2Te2.7Se0.3 thermoelectric alloy

Concentration‐dependent excess Cu doping behavior and influence on thermoelectric properties in Bi 2 Te 3

“…Details on Cu substitution will be discussed connected with the electronic transport properties, which exhibit strong dependence on the Curelated point defects. 17 Figure 2A,B shows the measured temperature dependences of σ and S of Cu x Bi 2 Te 3 (x = 0, 0.004, 0.008, 0.012, 0.016, and 0.02) samples. It is clearly shown that the σ value of the pristine Bi 2 Te 3 ($667 S cm À1 at 300 K) sample was largely increased both in Cu 0.004 Bi 2 Te 3 ($1307 S cm À1 at 300 K) and Cu 0.008 Bi 2 Te 3 ($1120 S cm À1 at 300 K) samples.…”

“…[3][4][5][6][7][8] However, the incorporated Cu was found at different sites such as intercalation or substitution sites within Bi 2 Te 3 lattice, and could even be precipitated. [9][10][11][12][13][14][15][16][17] The intercalation mechanism in Bi 2 Te 3 -based systems were also investigated with different dopants like Sn and CuI. [18][19][20] The improved reproducibility and enhanced zT was reported in Cu-intercalated n-type ternary Bi 2 Te 2.7 Se 0.3 .…”

“…5 Recently, doping behavior of excess Cu in the ternary Bi 2 Te 2.7 Se 0.3 was observed via atomicscale chemical mapping. 17 Excess Cu doping behavior in ternary Bi 2 Te 2.7 Se 0.3 has been directly demonstrated by atomic-scale chemical mapping: excessive Cu atoms in Bi 2 Te 2.7 Se 0.3 occupied (1) Bi-site at a low content of 0.2 at % (Cu 0.01 Bi 2 Te 2.7 Se 0.3 ) and (2) three crystallographic sites (Bi, Te, (1) and Te (2) ) and van der Waals gap (intercalation) at high content of 1.2 at% (Cu 0.06 Bi 2 Te 2.7 Se 0.3 ). 17 However, the doping behaviors of Cu in the ternary Bi 2 Te 2.7 Se 0.3 would be different from that reported in binary Bi 2 Te 3 .…”

Thermoelectric Performance Enhancement in Commercial Bi0.5Sb1.5Te3 Materials by Introducing Gradient Cu-Doped Grain Boundaries

“…For instance, the ZT of commercial p-type BST alloy is <1, but the material cost is about 8.63 × 10 5 $/W. Numerous strategies have been used to optimize TE parameters and subsequently enhance ZT values of Bi 2 Te 3 -based alloys, such as modulated doping, nanoengineering, and grain boundary engineering. − Cu doping has been confirmed as a general way to enhance the TE performance of p-type BTS materials, which always results in the simultaneously increasing of the power factor and thermal conductivity. − In p-type BST alloys, the Cu atoms prefer to enter the Sb sites, which could provide additional holes and enhance carrier mobility. For example, Chen et al reported a ZT value of 1.4 at 400–500 K in BST alloys via introducing Cu doping .…”

Enhanced Thermoelectric and Mechanical Performances in Sintered Bi0.48Sb1.52Te3–AgSbSe2 Composite

“…The commercial applications of both power generation and refrigeration are mainly based on zone-melted (ZM) Bi 2 Te 3 materials, which seriously suffer from mediocre TE properties and poor mechanical performance. − To meet the growing demand of applications, many efforts have been made to develop Bi 2 Te 3 sintered materials synthesized by hot pressing (HP), spark plasma sintering (SPS), and some derived approaches such as melt spinning (MS), , hot deformation (HD), − high-energy ball milling (BM), , and liquid-phase sintering (LPS). , Various sintering methods not only enhance the mechanical performance, but also introduce lattice distortion, dislocations, and nanograins to strengthen the phonon scattering and decrease κ l , resulting in a synergistic optimization of mechanical and TE properties for Bi 2– x Sb x Te 3– y Se y materials. Recently, the addition of a second-phase during the sintering process, a more direct scheme to introduce scattering centers into the matrix, has been widely applied into synchronously optimizing the phononic and electronic transport coefficients of the Bi 2 Te 3 -based composite systems. − Inspired by these aforementioned works, researchers keep exploring new composite systems to synthetically elevate the property of Bi 2– x Sb x Te 3– y Se y sintering materials.…”