单晶和多晶Skutterudite类材料的热--电性能和机理

研究稀土元素填充Skutterudite类新型热电材料，探索含活性稀土元素的复杂化合物单晶和多晶制备，优化材料设计，以进一步提高其热电性能。重点研究填隙稀原子对降低晶格热导率的作用，过渡族元素掺杂对载流子浓度和输送性的影响。改变材料晶粒尺寸，研究晶界对电子和声子的散射作用，确定合适的晶粒尺寸以获得高性能。明确各因素的作用机制。

In this study, the relationship between thermoelectric properties and crystal structure, microstructure and lattice defects has been investigated in two kinds of thermoelectric compounds. The crystal structure of the rare-earth filled skutterudite compounds was refined by Rietveld method. The effect of annealing conditions on the grain size of a skutterudite compound was studied and the activation energy of grain growth was.obtained. For polycrystalline skutterudite compounds, the effects of grain size on the thermoelectric properties are related to the carrier concentration..Specimens with a large grain size yield a relatively good performance. Thermal conductivity of the rare-earth filled skutterudite compounds is.insensitive to the grain size. Crystal structure has a large effect on the thermal conductivity in the Zn-Sb system. Inclusion of ZnSb and Zn as a.secondary phase in the β-Zn4Sb3 matrix increases the thermal conductivity. The thermoelectric performance of β-Zn4Sb3 based materials do not exceed.that of β-Zn4Sb3 in its bulk form. However, in Zn4Sb3 thin films, a high thermoelectric property can be obtained under certain processing conductions.which yield a suitable microstructure. The room temperature thermal conductivity of Zn4Sb3 thin films decrease with decreasing film thickness. The figure of merit of a film specimen is twice as large as its bulk counterpart at room temperature. This indicates a great potential to get improved thermoelectric properties in the thin film form..