Research On Preparation And Properties Of N-type Filled Skutterudite Thermoelectric Materials

The Skutterudite compounds, which have high Seebeck coefficient and appropriate electrical resistivity, always direct people's attention, but the thermal conductivity of this samples are higher. However, the filled Skutterudite compounds, which have lower thermal conductivity because of the phonon scattering of the lattice caused by the filled rare-earth large quality atoms, have been studied widely. In this research, mechanical alloying and hot press sintering are used to synthesis La filled Ni doped Skutterudite compounds. Using mechanical alloying to synthesis Skutterudite compounds can improve material's thermoelectric performance and short the time for preparation. The influence of different technical qualifications with the thermoelectric properties and microstructure is discussed in detail. Different content La and Ni atoms in LaxNiyCo4-ySb12 are also researched for the influence of the thermoelectric properties. Result shows that: For the preparation of the Co-Sb series Skutterudite compounds, after 10 hours' of mechanical alloying treatment, the as-MAed powders have a mixture structure but the Skutterudite phase have already existed. Consolidating the as-MAed powders by hot pressing at 600 ℃with 2 hours, solid state reaction takes place and Skutterudite phase is synthesized. When the hot press temperature and time increase, the thermoelectric properties have a linearly increase. At 400℃, the ZT value of La0.4Ni0.2Co3.8Sb12, which synthesized at 600℃by 50MPa pressure with 6 hours after 10 hours' MA, is 0.19. For the n-type Skutterudite compounds, when the Ni content changes, the Seebeck coefficient, electrical resistivity and thermal conductivity changes too. When Ni atoms doped into CoSb3 compounds, the thermoelectric properties changes a lot. At 400 ℃, the ZT value of the CoSb3 samples is 0.01, however the Ni0.2Co3.8Sb12 samples is 0.13. The ZT value of the La0.4Ni0.4Co3.6Sb12 samples is 0.10 at 400℃. When the filled La atoms increase, the lattice thermal conductivity decrease, The ZT value of the La0.6Ni0.4Co3.6Sb12 samples is 0.20 at 400℃.