| Thermoelectirc materials can mutually convert energy between heat and electricity,which demonstrated a new solid-state technology for potential applications in powergeneration and refrigeration. Thermoelectric devices are attracting more and more attentiondue to the advantages of small volume, light quality, high reliability, low pollution andnoiselessness, etc.. With the persistent efforts in thermoelectic materials developing, thethermoelectric properties have been greatly improved. For example, the dimensionless figureof merit, ZT, of the GeTe-based thermoelectic materials has been increased from1.0to higherthan2.0.The p-type Ge0.95-xPbxBi0.05Te (x=0.01,0.03,0.05,0.07,0.09) bulk thermoelectricalmaterials are prepared by high energy ball milling and direct current rapid hot pressingmethods in this dissertation. The sample of Ge0.94Pb0.01Bi0.05Te has the best thermoelectricproperties with a very high ZT value up to~2.0at670K. The other two groups ofthermoelectirc materials of Ge1-yBiyTe (y=0,0.01,0.03,0.05,0.07) and Ge1-zPbzTe (z=0,0.01,0.02,0.03) have been studied respectively for comparison. The results show that:(1) Bi leadsto decrease in the carrier concentration and the lattice thermal conductivity, but increase in theSeebeck coefficient.(2) Pb only causes lattice distortion to decrease the lattice thermalconductivity.(3) The Ge0.95-xPbxBi0.05Te composition has higher Seebeck coefficient andlower lattice thermal conductivity, but identical electrical conductivity compared withGe0.95Bi0.05Te composition. |
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