Solubility design leading to high figure of merit in low-cost Ce-CoSb3 skutterudites

Abstract

CoSb3-based filled skutterudite has emerged as one of the most viable candidates for thermoelectric applications in automotive industry. However, the scale-up commercialization of such materials is still a challenge due to the scarcity and cost of constituent elements. Here we study Ce, the most earth abundant and low-cost rare earth element as a single-filling element and demonstrate that, by solubility design using a phase diagram approach, the filling fraction limit (FFL) x in CexCo4Sb12 can be increased more than twice the amount reported previously (x=0.09). This ultra-high FFL (x=0.20) enables the optimization of carrier concentration such that no additional filling elements are needed to produce a state of the art n-type skutterudite material with a zT value of 1.3 at 850 K before nano-structuring. The earth abundance and low cost of Ce would potentially facilitate a widespread application of skutterudites.

Defect-Controlled Electronic Structure and Phase Stability in Thermoelectric Skutterudite CoSb3

“…into the lattice cages of the CoSb 3 structure to remarkably reduce the κ thermal conductivity. [10][11][12][13][14][15][16] For example, Shi et al proposed a simple electronegativity rule to determine whether a skutterudite phase with guest atoms can stably form. 16 The filling fraction limit (FFLs) of guest atoms was predicted in CoSb 3 by considering not only the interaction between the guest and host atoms but also the formation of secondary phases.…”

Micro- and Macromechanical Properties of Thermoelectric Lead Chalcogenides

“…Figure 3(a) shows the tensile-stress -tensile-strain relations. The lowest ideal tensile strength is found to be 5.55 GPa at 0.138 tensile strain along the [100] direction, which is lower shows an obvious 'yielding' process, which is similar to shearing along the (001)/<100> direction as discussed above, while tensions along both the [1][2][3][4][5][6][7][8][9][10] and [111] directions show a sudden drop in tensile stress. We extracted the structural and bond length changes at critical tensile strains to determine the bond-responding processes, as displayed in Figure 3 …”

“…We considered three typical tensile systems, [100], [1][2][3][4][5][6][7][8][9][10], and [111] with supercells containing 64, 48, and 48 atoms, respectively. Figure 3(a) shows the tensile-stress -tensile-strain relations.…”

“…1 Indeed the past two decades has seen dramatic enhancements in the TE figure of merit, zT = α 2 σ/κ, of various materials, achieved through simultaneously optimizing the power factor (α 2 σ) and reducing the thermal conductivity 2 for such materials as PbTe, [3][4][5] skutterudite CoSb 3 , [6][7][8] Bi 2 Te 3 , 9-11 Mg 2 Si, [12][13] and half-Heusler alloys. 14,15 However, despite the improved efficiencies, applications of these TE materials usually impose a severe cyclic temperature gradients that can generate cracks in the microstructure.…”

Elemental distributions within multiphase quaternary Pb chalcogenide thermoelectric materials determined through three-dimensional atom probe tomography

“…The interfacial concentration of sodium was 1.2 at.% and 4.5 at.% for the lightly--and heavily--doped samples respectively. Segregation of dopants to grain boundaries [22] and interfaces [2,23] has been reported for thermoelectric materials often. Solute atoms in a crystalline structure segregate to grain boundaries, secondary phase interfaces and lattice imperfections including dislocations and stacking faults, in order to minimize the overall free energy of the system [24].…”