11:00 AM - 11:15 AM
[5a-A503-2] Thermoelectric properties of As-based 122 Phase compounds
Keywords:thermoelectric materials, Zintl compounds
After discovery of iron-Arsenide superconductor, many kind of materials was investigated. This Iron-Arsenide superconductor family have wide variety of crystal systems, and their seebeck coefficient was reported. Iron-arsenide compounds exhibit bad metal with large Seebeck coefficient, which is advantageous for thermoelectric materials. For example, LnFeAsO (Ln = Lanthanide) exhibits large Seebeck coefficient of S ~ -100 μVK-1 at around 100 K. Controlling carrier concentration by oxygen deficiency, LaFeAsO1-y (y = 0.16) shows the power factor of PF = 0.41 mWm-1K-1 at T = 75 K and dimensionless figure-of merit of ZT = 0.061 at T = 125 K.
122-systems of AFe2As2 (A = Ca, Sr, Ba, Eu) crystallized in the ThCr2Si2-type structure (space group: I4/mmm), and poor thermo-electric properties was reported. In contrast, many good thermoelectric materials were reported on Sb-based 122-systems crystalized in the CaSi2Al2-type structure Examining Sb-based 122-systems is now one of hot topics in the development of thermoelectric materials.
We focused on a As-based zintl compounds which has stoichiometric ratio of 1 : 2 : 2, because thermoelectric materials research of zintl compounds in the past concentrated in the Sb-based series, there are few studies with P and As based compounds.
We synthesized various K concentration of Ba1-xKxZn2As2, systematically and measured its thermoelectric properties. Ba1-xKxZn2As2 has a crystalized in α-BaCu2S2 structure (space group: Pnma). K concentration x of 0 to 3% and crystalized in ThCr2Si2 structure at a concentration of 4% or more. The obtained value of κlattice was not dependent on the K concentration and was almost the same as the value of Sb based BaZn2Sb2.
We studied the thermoelectric properties of Ba1-xKxZn2As2 above room temperature. The highest value of ZT obtained was 0.67 at T = 900 K for x = 0.02.
122-systems of AFe2As2 (A = Ca, Sr, Ba, Eu) crystallized in the ThCr2Si2-type structure (space group: I4/mmm), and poor thermo-electric properties was reported. In contrast, many good thermoelectric materials were reported on Sb-based 122-systems crystalized in the CaSi2Al2-type structure Examining Sb-based 122-systems is now one of hot topics in the development of thermoelectric materials.
We focused on a As-based zintl compounds which has stoichiometric ratio of 1 : 2 : 2, because thermoelectric materials research of zintl compounds in the past concentrated in the Sb-based series, there are few studies with P and As based compounds.
We synthesized various K concentration of Ba1-xKxZn2As2, systematically and measured its thermoelectric properties. Ba1-xKxZn2As2 has a crystalized in α-BaCu2S2 structure (space group: Pnma). K concentration x of 0 to 3% and crystalized in ThCr2Si2 structure at a concentration of 4% or more. The obtained value of κlattice was not dependent on the K concentration and was almost the same as the value of Sb based BaZn2Sb2.
We studied the thermoelectric properties of Ba1-xKxZn2As2 above room temperature. The highest value of ZT obtained was 0.67 at T = 900 K for x = 0.02.