RESUMEN
The thermoelectric parameters are essentially governed by electron and phonon transport. Since the carrier scattering mechanism plays a decisive role in electron transport, it is of great significance for the electrical properties of thermoelectric materials. As a typical example, the defect-dominated carrier scattering mechanism can significantly impact the room-temperature electron mobility of n-type Mg3Sb2-based materials. However, the origin of such a defect scattering mechanism is still controversial. Herein, the existence of the Mg vacancies and Mg interstitials has been identified by synchrotron powder X-ray diffraction. The relationship among the point defects, chemical compositions, and synthesis conditions in Mg3Sb2-based materials has been revealed. By further introducing the point defects without affecting the grain size via neutron irradiation, the thermally activated electrical conductivity can be reproduced. Our results demonstrate that the point defects scattering of electrons is important in the n-type Mg3Sb2-based materials.
RESUMEN
Mg3Sb2-based compounds are promising thermoelectric materials because of their excellent thermoelectric performance, low cost, and good mechanical properties. In this work, Er, Dy, Gd, and Nd are all confirmed to be effective n-type dopants for optimizing the carrier concentration, increasing the density of states effective mass, and suppressing the ionized impurity scattering of Mg3Sb2-based compounds. By increasing the sintering temperature, a larger grain size can be achieved and can effectively improve the carrier mobility in the whole measured temperature range. As a result, maximum zT values above â¼1.6 at 673 K and average zTs above â¼1.0 between 300 and 673 K were achieved for Mg3.07Er0.03Bi0.5Sb1.5, Mg3.07Dy0.03Bi0.5Sb1.5, and Mg3.07Nd0.03Bi0.5Sb1.5. In addition, a high compressive strength of â¼180 MPa was obtained in Mg3.07Dy0.03Bi0.5Sb1.5. Therefore, rare-earth element-doped Mg3Sb2-based compounds are promising for thermoelectric applications.
