High-temperature thermoelectric studies of A {sub 11}Sb{sub 10} (A=Yb, Ca)
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616 (United States)
- California Institute of Technology, 1200 California Boulevard, Pasadena, CA 91125 (United States)
Large samples (6-8 g) of Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10} have been synthesized using a high-temperature (1275-1375 K) flux method. These compounds are isostructural to Ho{sub 11}Ge{sub 10}, crystallizing in the body-centered, tetragonal unit cell, space group I4/mmm, with Z=4. The structure consists of antimony dumbbells and squares, reminiscent of Zn{sub 4}Sb{sub 3} and filled Skutterudite (e.g., LaFe{sub 4}Sb{sub 12}) structures. In addition, these structures can be considered Zintl compounds; valence precise semiconductors with ionic contributions to the bonding. Differential scanning calorimetry (DSC), thermogravimetry (TG), resistivity ({rho}), Seebeck coefficient ({alpha}), thermal conductivity ({kappa}), and thermoelectric figure of merit (zT) from room temperature to at minimum 975 K are presented for A {sub 11}Sb{sub 10} (A=Yb, Ca). DSC/TG were measured to 1400 K and reveal the stability of these compounds to {approx}1200 K. Both A {sub 11}Sb{sub 10} (A=Yb, Ca) materials exhibit remarkably low lattice thermal conductivity ({approx}10 mW/cm K for both Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10}) that can be attributed to the complex crystal structure. Yb{sub 11}Sb{sub 10} is a poor metal with relatively low resistivity (1.4 m{omega} cm at 300 K), while Ca{sub 11}Sb{sub 10} is a semiconductor suggesting that a gradual metal-insulator transition may be possible from a Ca{sub 11-} {sub x} Yb {sub x} Sb{sub 10} solid solution. The low values and the temperature dependence of the Seebeck coefficients for both compounds suggest that bipolar conduction produces a compensated Seebeck coefficient and consequently a low zT. - Graphical abstract: Large samples (6-8 g) of Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10} have been synthesized from a Sn-flux method. Thermoelectric measurements from room temperature to 1075 K have been obtained. Both A {sub 11}Sb{sub 10} (A=Yb, Ca) materials exhibit remarkably low lattice thermal conductivity ({approx}10 mW/cm K for both Yb{sub 11}Sb{sub 10} and Ca{sub 11}Sb{sub 10}) that can be attributed to the complex crystal structure.
- OSTI ID:
- 21015791
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 4; Other Information: DOI: 10.1016/j.jssc.2007.02.007; PII: S0022-4596(07)00082-5; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTIMONIDES
CALCIUM COMPOUNDS
CALORIMETRY
ELECTRIC CONDUCTIVITY
SEMICONDUCTOR MATERIALS
SOLID SOLUTIONS
SPACE GROUPS
STABILITY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 1000-4000 K
TETRAGONAL LATTICES
THERMAL CONDUCTIVITY
THERMAL GRAVIMETRIC ANALYSIS
YTTERBIUM COMPOUNDS