摘要
The n-type filled and doped skutterudites Ga_(x)Co_(4)Sb_(12.3) and Ga_(0.2)Co_(4)Sb_(11.3)Te composites with the welldistributed GaSb nanoinclusions are synthesized through the manipulating of metastable Ga fillers and enrichment of Sb by an in-situ method with a proper annealing procedure.Ga atoms can fill the icosahedron cages of skutterudite at high temperature,but at low temperature,they are driven out from the lattice voids and form the second phase of GaSb at grain boundaries.The presence of GaSb second phases reduces the thermal conductivity effectively.Te doping leads to a significant increase in carrier concentration of Ga_(0.2)Co_(4)Sb_(11.3)Te,thus largely suppresses the bipolar effect of Ga_(x)Co_(4)Sb_(12.3),resulting in a great enhancement in power factor.Moreover,Te doping induces mass and strain fluctuation,which decreases the lattice thermal conductivity further.Consequently,the maximum ZT is increased from 0.56 for Ga_(0.2)Co_(4)Sb_(12.3) at 573 K to 1.48 for Ga_(0.2)Co_(4)Sb_(11.3)Te at 873 K,which is advantageous to improve the thermoelectric conversion efficiency for commercial application.
基金
supported by the National Natural Science Foundation of China(Nos.61604031,51672037 and 61727818)
the subproject of the National Key and Development Program of China(No.2017YFC0602102)
the Department of Science and Technology of Sichuan Province(No.2019YFH0009).
