Synthesis and thermoelectric properties of p-type- and n-type-filled skutterudite R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12}(R:Ce,Ba,Y;M:Fe,Ni)

Journal Article · Sun May 01 00:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1888048· OSTI ID:20713920

Xinfeng, Tang; Qingjie, Zhang; Lidong, Chen; Goto, Takashi; Hirai, Toshio ^[1]

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1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

Single-phase R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12}(x=0-3.0,y=0-0.7) compounds filled by Ce, Ba, and Y, and substituted by Fe and Ni are synthesized by using the solid-state reaction method and melting reaction method. The structure and the thermoelectric properties of R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12} are investigated systematically. The thermal parameter (B) of Ba and Ce filled in Sb-icosahedron voids in the skutterudite structure is larger than that of Sb and Co (Fe). The maximum filling fraction of Ce and Ba (y{sub max}) for R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} increases with the increasing Fe content, and it is found that the maximum filling fraction of Ba (y{sub max}) is greater than that of Ce{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12}. The filling atoms Ba, Ce, and Y in Sb-icosahedron voids can reduce the lattice thermal conductivity of R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12} compounds remarkably, and the lattice thermal conductivity decreases in the order of ionic radii decreasing of Ba{sup 2+}, Ce{sup 3+}, and Y{sup 3+}. When Ce and Ba filing fraction is 0.3-0.4, the lattice thermal conductivity of R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} compounds reaches a minimum value. The lattice thermal conductivity can be greatly reduced by substituting Co with Fe or Ni, and compared with Fe substitution, the substituted atoms Ni are more effective in reducing the lattice thermal conductivity. The filling atoms Ba, Ce, and Y, and the substituted atoms Fe and Ni influence electrical transport properties of R{sub y}M{sub x}Co{sub 4-x}Sb{sub 12} compounds significantly. The carrier concentration and electrical conductivity of p-type R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} increase with the increasing Fe content but decrease with the increasing R filling fraction. At the same carrier concentration, electrical conductivity of p-type Ba{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} is larger than that of p-type Ce{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12}. Electrical conductivity of n-type Ba{sub y}Ni{sub x}Co{sub 4-x}Sb{sub 12} increases with the increasing Ni content remarkably. The Seebeck coefficient of p-type R{sub y}Fe{sub x}Co{sub 4-x}Sb{sub 12} increases with the increasing Ce and Ba filling fraction and with the decreasing Fe content, and Seebeck coefficient of n-type Ba{sub y}Ni{sub x}Co{sub 4-x}Sb{sub 12} decreases with the increasing Ni content. In the present study, the obtained maximum ZT values reach 1.1 and 1.25 for p-type Co-rich Ce{sub 0.28}Fe{sub 1.5}Co{sub 2.5}Sb{sub 12} (at 750 K) and n-type Ba{sub 0.30}Ni{sub 0.05}Co{sub 3.95}Sb{sub 12} (at 900 K), respectively.

• OSTI ID: 20713920
• Journal Information: Journal of Applied Physics, Vol. 97, Issue 9; Other Information: DOI: 10.1063/1.1888048; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIMONY COMPOUNDS
BARIUM COMPOUNDS
BARIUM IONS
CARRIER DENSITY
CERIUM COMPOUNDS
CERIUM IONS
CHARGED-PARTICLE TRANSPORT
COBALT COMPOUNDS
ELECTRIC CONDUCTIVITY
IRON COMPOUNDS
NICKEL COMPOUNDS
QUATERNARY ALLOY SYSTEMS
SEEBECK EFFECT
SYNTHESIS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
YTTRIUM COMPOUNDS
YTTRIUM IONS