Thermoelectric properties of YMn4+xAl8 − x for −2 ≤ x ≤ 2.5

Seven samples within the series YMn4+xAl8 − x (−2.0 ≤ x ≤ 2.5) were synthesized using direct reaction of the elements. The thermoelectric properties of the samples were characterized by measurements of resistivity, thermal conductivity and thermopower. According to transport measurements, slight Mn-deficiency influences the electronic conductivity of the YMn4+xAl8 − x system, implying that the electronic structure is marginal to the metal-semiconductor boundary. Furthermore, the ZT values of the samples prepared in this study were low. Experimental results indicated that structurally ordered YMn4Al8 shows metallic conductivity, whereas off-stoichiometric compounds displayed semiconductor-like behavior, at low temperatures.