Probing the Effects of Alloying, Grain Size, and Turbostratic Disorder on Thermal Conductivity

Abstract

We review a synthetic strategy for investigating the various effects of thermal conductivity reducing mechanisms in thermoelectric materials. Elemental nanolaminate precursors are used to selfassemble [(Bi 1−x Sb x 2 Te 3 ] m [(TiTe 2 1 36 ] n intergrowth thin films with controlled and well-defined composition and nanostructure, allowing the influence of alloying, effective grain size, and turbostratic disorder on the cross-plane thermal conductivity to be independently and collectively assessed. By combining all three features, thermal conductivity values well below the predicted minimum thermal conductivity of the components are obtained. These approaches, potentially combined with temperature dependent measurements, can offer a useful way to study phonon scattering mechanisms in thermoelectric materials.

Rapid synthesis and thermoelectric properties of In0.1Co4sb11Te0.8Ge0.2 alloys via high temperature and high pressure

“…As we see, clear and abundant grain boundaries are observed, which agree with the advantage of the HTHP synthesis of introducing abundant grain boundary [18]. More abundant grain boundaries are helpful to strengthen the hot phonon scattering, thus decreasing the lattice thermal conductivity [19,20]. The HRTEM micrographs of In 0.1 Co 4 sb 11 Te 0.8 Ge 0.2 are exhibited in Figure 3C and D. We can observe that the lattice orientation is in a disorderly growth pattern (see white arrows), and dislocations were found in lattices shown in the enlarged section of Figure 3C (see bottom-left corner).…”

“…What is more, the disorder lattice deformation, dislocations (see Fig. 3C and D) are the main reason for the reduction of j, which could enhance the point-defect, increasing phonon scattering [24]. Broadly speaking, high pressure, Te-Ge co-substituted and In filling in our samples play the important role in reducing thermal conductivity.…”

Self-assembly of designed precursors: A route to crystallographically aligned new materials with controlled nanoarchitecture

“…There are only three systems involving alloying of constituents using the MER approach reported, including that of (SnSe) 1+δ (Ta x V 1-x )Se 2 reported here. The synthesis and properties of [(TiTe 2 ) 1 + δ ] x [(Bi 2-x Sb x ) 2 Te 3 ] y alloys was reported by Mortensen et al, [98] the rock salt constituent was alloyed in ([Pb x Sn 1-x ]Se) z TiSe 2 , [ 99] and the transition metal constituent was alloyed in (SnSe) z (Nb x Mo 1-x )Se 2 . [37] ORDERED ABCB ALLOYS Ordered A m B n C p or more complex sequences of three compounds, such as A m B n C p B q , where A, B and C are compounds containing three compositionally different constituents, three structurally different constituents or a mix of these can be prepared expanding the calibration procedure described above.…”

Rapid synthesis and enhanced thermoelectric properties of Ba8Cu6Ge8xSi40−8x (x = 0, 1, 2, 3) alloys prepared using high-temperature, high-pressure method

“…On one hand, the increase of the cage radius caused by the higher content of Ge leads to a greater rattling of Ba atoms [25] inside the oversized cages. On the other hand, both high pressure and Si/Ge alloying introduce a large number of lattice defects, which aid in strengthening the phonon scattering, thus decreasing the lattice thermal conductivity [26,27]. Fig.…”