TY - JOUR
T1 - Electronic structure and thermoelectric properties of pnictogen-substituted A Sn1.5Te1.5 (A Co, Rh, Ir) skutterudites
AU - Zevalkink, Alex
AU - Star, Kurt
AU - Aydemir, Umut
AU - Snyder, G. Jeffrey
AU - Fleurial, Jean Pierre
AU - Bux, Sabah
AU - Vo, Trinh
AU - Von Allmen, Paul
N1 - Publisher Copyright:
© 2015 AIP Publishing LLC.
PY - 2015/7/21
Y1 - 2015/7/21
N2 - Substituting group 14 and 16 elements on the pnictogen site in the skutterudite structure yields a class of valence-precise ternary AX1.5Y1.5 compounds (ACo, Rh, Ir, XSn, Ge, and YS, Se, Te), in which X and Y form an ordered sub-structure. Compared with unfilled binary skutterudites, pnictogen-substituted phases exhibit extremely low lattice thermal conductivity due to increased structural complexity. Here, we investigate the role of the transition metal species in determining the electronic structure and transport properties of ASn1.5Te1.5 compounds with ACo, Rh, Ir. Density functional calculations using fully ordered structures reveal semiconducting behavior in all three compounds, with the band gap varying from 0.2 to 0.45eV. In CoSn1.5Te1.5, the electronic density of states near the gap is significantly higher than for AIr or Rh, leading to higher effective masses and higher Seebeck coefficients. Experimentally, Ir and Rh samples exhibit relatively large p-type carrier concentrations and degenerate semiconducting behavior. In contrast, CoSn1.5Te1.5 shows mixed conduction, with n-type carriers dominating the Seebeck coefficient and light, high mobility holes dominating the Hall coefficient. zT values of up to 0.35 were obtained, and further improvement is expected upon optimization of the carrier concentration or with n-type doping.
AB - Substituting group 14 and 16 elements on the pnictogen site in the skutterudite structure yields a class of valence-precise ternary AX1.5Y1.5 compounds (ACo, Rh, Ir, XSn, Ge, and YS, Se, Te), in which X and Y form an ordered sub-structure. Compared with unfilled binary skutterudites, pnictogen-substituted phases exhibit extremely low lattice thermal conductivity due to increased structural complexity. Here, we investigate the role of the transition metal species in determining the electronic structure and transport properties of ASn1.5Te1.5 compounds with ACo, Rh, Ir. Density functional calculations using fully ordered structures reveal semiconducting behavior in all three compounds, with the band gap varying from 0.2 to 0.45eV. In CoSn1.5Te1.5, the electronic density of states near the gap is significantly higher than for AIr or Rh, leading to higher effective masses and higher Seebeck coefficients. Experimentally, Ir and Rh samples exhibit relatively large p-type carrier concentrations and degenerate semiconducting behavior. In contrast, CoSn1.5Te1.5 shows mixed conduction, with n-type carriers dominating the Seebeck coefficient and light, high mobility holes dominating the Hall coefficient. zT values of up to 0.35 were obtained, and further improvement is expected upon optimization of the carrier concentration or with n-type doping.
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U2 - 10.1063/1.4926479
DO - 10.1063/1.4926479
M3 - Article
AN - SCOPUS:84937509698
VL - 118
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 3
M1 - 035107
ER -