Effects of nano-TiO_2 dispersion on the thermoelectric properties of filled-skutterudite Ba_(0.22)Co_4Sb_(12)

摘要

Homogeneously dispersed nano-TiO_2 was introduced into the matrix of n-type barium-filled cobalt antimony (Ba_(0.22)Co_4Sb_(12)) via sol-gel method successfully. The Seebeck coefficients are improved and the lattice thermal conductivities are depressed with a proper addition of nano-Ti02 not more than 0.8 vo 1. percent, while the electrical conductivities nearly remain unchanged. The effects of n-type semi conductive nanoscale inclusions on the electrical and thermal transport characteristics are discussed. Microstructure analyses indicate that the fine nanoinclusions locate on the grain boundaries as well as inside grains, which serve as extra phonon scattering mode and new type energy filtering. As a result, the optimal ZT value was achieved for the sample of 0.4 vol. percent TiO_2 composition.