Trends in Electrical Transport of p-type Skutterudites RFe4Sb12 (R-Na,K,Ca,Sr,Ba,La,Ce,Pr,Yb) from First Principles Calculations and Boltzmann Transport Theory
- Chinese Academy of Sciences
- Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)
- ORNL
We report a consistent set of ab initio calculations of the electronic structures and electrical transport properties of p-type thermoelectric compounds RFe{sub 4}Sb{sub 12}, where R is a rattling filler selected from alkali metals (Na, K), alkaline earths (Ca, Sr, Ba), and rare earth metals (La, Ce, Pr, Yb). Different from the single Sb-dominated light band in the valence band edge of CoSb{sub 3}, the heavy bands from Fe d electronic states also fall in the energy range close to the valence band edges in the RFe{sub 4}Sb{sub 12}. These heavy bands dominate the band-edge density of states, pin the Fermi levels, and mostly determine the electrical transport properties of those p-type RFe{sub 4}Sb{sub 12}. The Seebeck coefficients can be roughly categorized into three groups based on the charge states of fillers, and the maxima are lower than those of n-type CoSb{sub 3} skutterudites. Effective carrier relaxation time in p-type RFe{sub 4}Sb{sub 12}, obtained from the combinations of calculations and experiments, is remarkably similar among different compounds with values around 7.5 x 10{sup -15} s and weak temperature dependence. The optimal doping levels of those RFe{sub 4}Sb{sub 12} are estimated to be around 0.6-0.8 holes per unit cell at 850 K, which is difficult to achieve in RFe{sub 4}Sb{sub 12} compounds. Prospects for further improving the performance of p-type skutterudites are also discussed.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1039592
- Journal Information:
- Physical Review B, Vol. 84, Issue 23; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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