Phase diagram, crystal chemistry and thermoelectric properties of compounds in the Ca-Co-Zn-O system

Journal Article · Thu Nov 17 00:00:00 EST 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.06.013· OSTI ID:1025044

Wong-Ng, W; Luo, T; Xie, W; Tang, W H; Kaduk, J A; Huang, Q; Yan, Y; Chattopadhyay, S; Tang, X; Tritt, T ^[1]

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1. IIT

In the Ca-Co-Zn-O system, we have determined the tie-line relationships and the thermoelectric properties, solid solution limits, and structures of two low-dimensional cobaltite series, Ca₃(Co, Zn)₄O_9-z and Ca₃(Co,Zn)₂O_6-z at 885 ºC in air. In Ca₃(Co,Zn)₄O_9-z, which has a misfit layered structure, Zn was found to substitute in the Co site to a limit of Ca₃(Co_3.8Zn_0.2)O_9-z. The compound Ca₃(Co,Zn)₂O_6-z (n=1 member of the homologous series, Ca_n+2(Co,Zn)n(Co,Zn)'O_3n+3-z) consists of one-dimensional parallel (Co,Zn)₂O₆^6- chains that are built from successive alternating face-sharing (Co,Zn)O₆ trigonal prisms and 'n' units of (Co,Zn)O₆ octahedra along the hexagonal c-axis. Zn substitutes in the Co site of Ca₃Co₂O₆ to a small amount of approximately Ca₃(Co_1.95Zn_0.05)O_6-z. In the ZnO-CoO_z system, Zn substitutes in the tetrahedral Co site of Co₃O₄ to the maximum amount of (Co_2.49Zn_0.51)O_4-z and Co substitutes in the Zn site of ZnO to (Zn_0.94Co_0.06)O. The crystal structures of (Co_2.7Zn_0.3)O_4-z, (Zn_0.94Co_0.06)O, and Ca₃(Co_1.95 Zn_0.05)O_6-z are described. Despite the Ca₃(Co, Zn)₂O_6-z series having reasonably high Seebeck coefficients and relatively low thermal conductivity, the electrical resistivity values of its members are too high to achieve high figure of merit, ZT.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: DOE - BASIC ENERGY SCIENCES
• OSTI ID: 1025044
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue (8) ; 08, 2011; ISSN 0022-4596
• Publisher: Elsevier
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
AIR
CHAINS
CHEMISTRY
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
PERFORMANCE
PHASE DIAGRAMS
PRISMS
SOLID SOLUTIONS
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES