Thermoelectric properties of Zn-doped Ca3AlSb3

Abstract

Polycrystalline samples of Ca 3 Al 1Àx Zn x Sb 3 , with x ¼ 0.00, 0.01, 0.02, and 0.05 were synthesized via a combined ball milling and hot pressing technique and the influence of zinc as a dopant on the thermoelectric properties was studied and compared to the previously reported transport properties of sodium-doped Ca 3 AlSb 3 . Consistent with the transport in the sodium-doped material, substitution of aluminum with zinc leads to p-type carrier conduction that can be sufficiently explained with a single parabolic band model. It is found that, while exhibiting higher carrier mobilities, the doping effectiveness of zinc is lower than that of sodium and the optimum carrier concentration for a maximum figure of merit zT is not reached in this study. We find that the grain size influences the carrier mobility, carrier concentration, and lattice thermal conductivity, leading to improved properties at intermediate temperatures, and highlighting a possible approach for improved figures of merit in this class of materials.

Thermoelectric properties of the Yb9Mn4.2−xZnxSb9solid solutions

“…3 and 4. The Mn analogue, Yb 9 Mn 4.2 Sb 9 , is a line compound with an electron decient composition, resulting in a carrier concentration of 9 were calculated from XRD results using Rietveld fits. As the amount of Zn increases, each parameter changes linearly from the Mn end member side to the Zn end member and this follows a reported trend 37,38 Composition (Fig.…”

“…5,6 They oen have very low lattice thermal conductivity due to their large unit cells, and it is possible to nely tune their electronic properties by doping, providing a route to improved zT. High thermoelectric efficiency has been demonstrated in a number of different Zintl compounds [7][8][9][10][11][12][13][14][15][16][17] including Yb 14 MnSb 11 (ref. 16 and 18) and YbCd 2Àx Zn x Sb 2 , both of which have zT values above unity at high temperatures.…”

“…37,38 Partially occupied Minterstitial sites (yellow spheres) link neighboring M 4 Sb 9 ribbons into a pseudo two-dimensional framework. 9) determined from renement of single crystal X-ray diffraction data.…”

Thermoelectric properties of Sr3GaSb3 – a chain-forming Zintl compound

“…Our previous study of Ca 3 AlSb 3 indicates that with the correct processing it is possible to avoid this activated behavior, drastically increasing electrical conductivity. 31 At higher temperatures (>600 K) the mobility in Sr 3 Ga 1Àx Zn x Sb 3 is limited by acoustic phonon scattering, for which the temperature dependence is given by m H f T Àv , with n between 1 and 1.5 for degenerate and non-degenerate behavior, respectively.…”

Thermal and mechanical properties of La–Al–Sb alloys

“…One of the materials with high thermoelectric performance is Ca-Al-Sb discovered by Toberer et al [5]. After this discovery, it is pointed out that Ca-AlSb alloys with different stoichiometry have also high thermoelectric performance [5][6][7][8][9][10][11][12]. For example, Seebeck coefficient of Ca 5 Al 2 Sb 6 is larger than 450 lV/K at room temperature.…”