A series of single crystal samples, Yb 14MnSb 11-xTe x (x ≤ 0.2), were investigated via Sn flux. The element distributions were mapped using an electron microprobe, which demonstrated inhomogeneity and limited solubility of Te in the crystals. The magnetic properties of two crystals of compositions Yb 13.80(2)Mn 1.03(1)Sb 11.11(4)Te 0.06(3) and Yb 13.82(3)Mn 1.02(1)Sb 11.02(8)Te 0.14(6) were investigated. Increasing amounts of Te increase the saturation moment of Yb 14MnSb 11-xTe x, and slightly lower the ordering temperature T C by about 1 K. This is attributed to the filling of the hole in Yb 14MnSb 11 and the reduction of the screening of the Mn 2+ d 5 electrons, resulting in a higher effective moment. Hot-pressed, fully dense pellets of Yb 13.72(3)Mn 1.08(1)Sb 11.13(6)Te 0.07(5), Yb 13.76(5)Mn 1.11(1)Sb 10.96(8)Te 0.16(8), and Yb 13.76(4)Mn 1.10(2)Sb 10.95(9)Te 0.19(7) were prepared for thermoelectric property measurements. Both Seebeck coefficient and electrical resistivity increase with increasing amount of Te as a result of decreasing carrier concentration. Increasing amounts of YbTe with increasing x could be identified in the electron microprobe. The total thermal conductivity was approximately the same for all compositions, similar to that of Yb 14MnSb 11. The figure of merit zT reaches a maximum of 1.11 for x = 0.07 at 1240 K, which is approximately 12% higher than the parent compound, Yb 14MnSb 11.
ASJC Scopus subject areas
- Materials Chemistry