Effect of segregated impurity phases on lattice thermal conductivity in Y-added CoSb3

Three preparation methods – quenching, sintering and annealing – have been employed to synthesize Y-filled skutterudite compounds YxCo4Sb12 (0.00 ⩽ x ⩽ 0.35). Y atoms do not fill the vacancy sites in the skutterudite structure in the form of YxCo4Sb12. YSb and CoSb2 are formed as impurity phases when Y is added. The lattice thermal conductivity is reduced by 30% by Y addition, indicating that the segregated impurity phases strongly scatter.