p-Type skutterudites RxMyFe3CoSb12 (R, M = Ba, Ce, Nd, and Yb): Effectiveness of double-filing for the lattice thermal conductivity reduction

Ab-initio calculations of the resonant modes and frequencies for a number of possible fillers in p-type RFe₃CoSb₁₂ and RFe₄Sb₁₂ were carried out. The results indicate that, although the exact values of fillers’ resonant frequencies in p-type skutterudites are somewhat different from those in n-type Co-based skutterudites, the Einstein-like resonant modes of the fillers are similar to those in n-type materials. Experimentally, several pairs of the fillers were selected and double-filled p-type skutterudite compounds R{sub x}M{sub y}Fe₃CoSb₁₂ (R, M = Ba, Ce, Nd, and Yb) were successfully synthesized. The reduction in the lattice thermal conductivity was realized by extending the range of resonant frequencies. As a result, enhanced ZT values above unity were achieved in these double-filled p-type skutterudites.. Authors: Liu, Ruiheng [CAS Key Lab. for Energy-conversion Materials, Shanghai Inst. of Ceramics, Chinese Academy of Sciences (CAS), Shanghai (China)]; Yang, Jiong [State Key Lab. of High Perf. Ceramics and Superfine Microstructure, Shanghai Inst. of Ceramics, Chinese Academy of Sciences (CAS), Shanghai (China)]; Cheng, Xihong [CAS Key Lab. for Energy-conversion Materials, Shanghai Inst. of Ceramics, Chinese Academy of Sciences (CAS), Shanghai (China)]; Shi, Xun [State Key Lab. of High Perf. Ceramics and Superfine Microstructure, Shanghai Inst. of Ceramics, Chinese Academy of Sciences (CAS), Shanghai (China)]; Chen, Lidong [CAS Key Lab. for Energy-conversion Materials, Shanghai Inst. of Ceramics, Chinese Academy of Sciences (CAS), Shanghai (China)]. DOE Contract: SC0000957. Subjects: 36 MATERIALS SCIENCE; charge transport; defects; electrodes - solar; materials and chemistry by design; optics; phonons; solar (photovoltaic); solar (thermal); synthesis (novel materials); synthesis (self-assembly); thermal conductivity; thermoelectric