Correlation between microstructure and drastically reduced lattice thermal conductivity in bismuth telluride/bismuth nanocomposites for high thermoelectric figure of merit

Abstract

a b s t r a c tThe concept of nanocomposite/nanostructuring in thermoelectric materials has been proven to be an effective paradigm for optimizing the high thermoelectric performance primarily by reducing the thermal conductivity. In this work, we have studied the microstructure details of nanocomposites derived by incorporating a semi-metallic Bi nanoparticle phase in Bi 2 Te 3 matrix and its correlation mainly with the reduction in the lattice thermal conductivity. Incorporating Bi inclusion in Bi 2 Te 3 bulk thermoelectric material results in a substantial increase in the power factor and simultaneous reduction in the thermal conductivity. The main focus of this work is the correlation of the microstructure of the composite with the reduction in thermal conductivity. Thermal conductivity of the matrix and nanocomposites was derived from the thermal diffusivity measurements performed from room temperature to 150 1C. Interestingly, significant reduction in total thermal conductivity of the nanocomposite was achieved as compared to that of the matrix. A detailed analysis of high-resolution transmission electron microscope images reveals that this reduction in the thermal conductivity can be ascribed to the enhanced phonon scattering by distinct microstructure features such as interfaces, grain boundaries, edge dislocations with dipoles, and strain field domains.

Mechanisms of thermoelectric efficiency enhancement in Lu-doped Bi2Te3

“…The contributions from k e , k p and k b for Bi 2 Te 3 are shown in figure 5(b). The electronic thermal conductivity seems to be anomalous high [43]. So, using the Lorenz number for metals results in incorrect estimate of k e .…”

Scalable colloidal synthesis of Bi2Te2.7Se0.3 plate-like particles give access to a high-performing n-type thermoelectric material for low temperature application

“…A minimal κ  0.7 Wm -1 K -1 at 300 K is attained, which is among the lowest reported [15][16][17][18][19][20][21][22][29][30][31][32] in polycrystalline n-type Bi2Te3 based composition and can mainly be attributed to the plate-like microstructural features of the constituting particles (Figure 2). 62 The lattice thermal conductivity calculated using the equation = − and is presented along with in Figure 4e. The κL is significantly suppressed at lower temperature, which can be attributed to grain boundary scattering resulting from bulk nanostructuring in the SPS-sintered BTS.…”

Compositional Fluctuations Mediated by Excess Tellurium in Bismuth Antimony Telluride Nanocomposites Yield High Thermoelectric Performance

“…To further enhance the ZT of this optimally alloyed composition, doping with Cu, , Cd, Ag, , and Pb and nanostructuring via ball milling, ,,,, melt spinning, − and chemical synthesis , have been extensively carried out. Similarly, composite aspects of hybridization with nanoparticles (NPs) such as Bi, Sb 2 O 3 , SiC, ZnO, Zn 4 Sb 3 , PbSe, Y 2 O 3 , and SiO 2 were demonstrated for tuning the TE transport favorably.…”