Exploration and Optimization of Tellurium‐Based Thermoelectrics

Thallium‐based chalcogenides clearly show good potential for thermoelectric materials with
their uniquely low lattice thermal conductivity values which lead to the excellent overall values of ~1
W∙m ‐1 K ‐1 with Tl9BiTe6. With this exceptionally low thermal conductivity and a simple system to
synthesize in the laboratory, research on the thermoelectric properties has already expanded into
alternate directions with numerous ternary thallium chalcogenide compounds, usually this involves
other heavy p‐block elements, but late‐transition‐metal inclusions have also shown promising results.
Studies on Tl2GeTe3, [238] Tl2SnTe3 (ZT = 0.6 at 300 K), [239] AgTlTe (ZT = 0.61 at 580 K), [240] TlSbTe2 (ZT =
0.87 at 715 K), [241] TlBiTe2 (ZT = 0.15 at 760 K), [242] and the current rival to Tl9BiTe6, AgTl9Te5 with ZT =
1.23 at 700 K [243] are all being worked on in past and recent years due to the high expectations for
thallium tellurides.
The aim of this work herein is to further expand the research in the field of thallium tellurides
through phase ranges and doping experiments. Sample sizes in this section (Section IV) range from
~0.75 g to ~1 g to ensure sufficient quantities for physical property measurements. Taking into
consideration the strong thermoelectric properties of Tl9BiTe6, questions arise about other heavy p‐
block elements such as Pb, Sn, or Sb. Through the use of traditional solid state techniques several
systems including modifications of Tl9BiTe6, Tl9SbTe6, and Tl4SnTe3 will be investigated with additional
elements or site deficiencies in attempt to further optimize the thermoelectric properties for power
generation. Since the structures are so similar in nature the alloying of structures may benefit the
properties as well.
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