The Zintl phase, Yb14MnSb11, has been recently identified as a potential thermoelectric material because of its high figure of merit (zT) above 1000 K. Tuning the carrier concentration with La3+ provided an improved zT at high temperatures. Rare earth elements provide additional tuning through size, electron donor properties, and effects on bonding. The solubility of the rare earth, Tm, was explored to provide chemical pressure and enhance the Seebeck coefficient of Yb14MnSb11. Crystals were prepared via Sn flux synthesis with the compositional fluxes of Yb14-xTmxMnSb11 (x = 0.3 (1), 0.5 (2), 0.7 (3)). The incorporation of Tm does not significantly alter the unit cell parameters of Yb14MnSb11. The content of Tm was probed with wavelength dispersive microprobe analysis and showed that the maximum amount of Tm is 0.44 with the composition being Yb13.34(6)Tm0.44(1)Mn1.04(2)Sb11.19(6). Single crystal compositions of Yb14-xTmxMnSb11 (x = 0.29 (1), 0.40 (2), and 0.44 (3)) were measured. Samples were hot pressed and thermoelectric properties measured from 300-1200 K. The hot pressed pellets showed very similar Tm composition of approximately x = 0.4. All the samples show enhanced Seebeck coefficients and slightly higher electrical resistivity as compared with Yb14MnSb11, as expected for the addition of Tm3+ in this p-type compound. Total thermal conductivity is approximately the same as Yb14MnSb11 leading to a maximum zT of 0.81 at 1195 K for sample 2 with nominal composition Yb13.35(4)Tm0.44(1)Mn1.027(6)Sb11.18(4).
- High temperature thermoelectric
- High zt
- Power generation
ASJC Scopus subject areas
- Materials Science(all)