Synthesis of N-type thermoelectric materials, including Mg—Sn—Ge materials, and methods for fabrication thereof
Discussed herein are systems and methods for fabrication of MgSnGe-based thermoelectric materials for applications from room temperature and near room temperature to high temperature applications. The TE materials may be fabricated by hand or ball milling a powder to a predetermined particle size and hot-pressing the milled powder to form a thermoelectric component with desired properties including a figure of merit (ZT) over a temperature range. The TE materials fabricated may be disposed in thermoelectric devices for varying applications.
1. A method of manufacturing an n-type thermoelectric material comprising:
hot-pressing a powder comprising:
a first component consisting of magnesium (Mg);
a second component consisting of tin (Sn); and
a third component consisting of germanium (Ge); according to the formula Mg 2 Sn 0.75 Ge 0.25 into a pressed component, wherein the pressed component comprises a ZT value of at least 1.0 at about 450° C.
2. The method of claim 1 , wherein, prior to hot-pressing, the powder is formed using ball-milling.
3. The method of claim 2 , wherein the powder is ball-milled for up to 20 hours.
4. The method of claim 2 , wherein the powder is hot-pressed between about 600° C. and about 800° C. from about 1 second to about 30 minutes.
5. The method of claim 1 , wherein the ZT value is about 1.4 at about 450° C.
6. The method of claim 1 , wherein a power factor of the pressed component is from about 45 μW cm −1 K −2 to about 55 μW cm −1 K −2 from about 350° C. to about 450° C.
7. The method of claim 1 , wherein hot-pressing the powder comprises holding the powder at a temperature from about 500° C. to about 800° C. for a period of about 1 second to about 30 minutes.
8. The method of claim 1 , wherein the powder is a pure phase powder.
9. The method of claim 1 , further comprising annealing the pressed component from about 300° C. to about 500° C. from about 0.3 h to about 5 h.
10. A thermoelectric device comprising:
an n-type thermoelectric material comprising:
a first component consisting of magnesium (Mg);
a second component consisting of tin (Sn); and
a third component consisting of germanium (Ge); according to the formula Mg 2 Sn 0.75 Ge 0.25 into a pressed component, wherein the pressed component comprises a ZT value of at least 1.0 at about 450° C. and a power factor of about 52 μW cm −1 K −2 at about 25° C. to 450° C.