Study On Preparation And Properties Of β-FeSi₂ Based Thermoelectric Materials

Thermoelectric materials, which can realize thermoelectric conversion directly without any mechanical equipments and noise, are attractive as a kind of save-energy materials. Iron disilicide(β-FeSi₂) is one of the most promising thermoelectric candidates, due to its high Seebeck coefficient, abundance as a raw material, low cost, high oxidation resistance, non-toxicity, and high working temperature.β-FeSi₂ based thermoelectric materials were prepared by mechanical alloying (MA).By means of analysis of thermoelectric properties, XRD measurement and some others, the optimum processing parameters were obtained and the thermoelectric properties and phased structure of prepared samples were sdudied and analysed. In addition, thermoelectric convertors and their important performance parameters were introduced and the basic cells of thermoelectric convertors were constructed.The optimized preparing processing was as follows. By milling for 50 h with the ball-to-powder ratio being 15:1 and rotation speed being 365 r/min, the mixed powder can be completely alloyed after sintering at 890℃for 15 h in Ar atmosphere. On the studying of thermoelectric properties ofβ-FeSi₂ based alloys, it showed that cobalt is an effective n-type dopant, and its best doping concentration is 1at.%. While manganese benefits to the p-type alloy, the maximum of powder factor of which can be achieved with 2.67at.% manganese. Alumimum is a less effective p-type dopat than manganese, the best doping concentration of which is 1.64at.%. The thermoelectric property of the dopedβ-FeSi₂ with 0.67at.% cobalt can be further improved by doping 2mass% erbium oxide.According to the principles of thermoelectric effects, the cells of thermoelectric generator and thermoelectric cooler were both constructed by the cobalt-doped and manganese-doped sampleds with the best doping concentration. On giving the condtions of temperature and electricity, a thermoelectric current of 24μA and a thermoelectrically cooled temperature of 16℃were obtained, respectively.