Ag/Sb比对(GeTe)_(85)(Ag_ySb_(2-y)Te_(3-y))_(15)合金热电性能的影响

Effect of Ag / Sb Ratio on the Thermoelectric Properties of (GeTe)_(85) ( Ag_y Sb_(2-y) Te_(3-y))_(15) TAGS Alloys

按不同Ag/Sb比制备了(GeTe)85(AgySb2-yTe3-y)15(y=1.0,1.02,1.2,1.3,1.5)系列TAGS热电材料,发现偏化学计量比的样品中有Ag8GeTe6低热导率第二相的析出。改变Ag/Sb比能显著降低材料的晶格热导率,y=1.3样品的晶格热导率在700K约为基体相的40%。样品的电导率随着y值的增加先增加后减小,Seebeck系数随成分的变化规律与电导率相反,随着Ag/Sb比增加而减小。y=1.02样品在744K时获得最大ZT值1.37,与等化学计量比y=1.0样品相比提高了10%左右,且随着温度的进一步升高,ZT值有继续上升的趋势。

（GeTe）85（AgySb2-yTe3-y）15 （y=l. 0,1.02,1.2,1.3,1.5） TAGS alloys with different Ag/Sb ratio were synthesized and Ag8 GeTe6 with low thermal conductivity as the second phase was found in nonstoichiometric samples. The lattice thermal conductivity could be greatly decreased by changing the Ag/Sb ratio and the value was as low as 0.2Wm-1 K-1 for the sample with y= 1.3 at 700K. However, the electrical conductivity of the samples increased first and then decreased, while the Seebeck coefficient behaved inversely, as the Ag/Sb ratio increased. The maximum ZT value of about 1.37 was obtained at 744K for the sample with y=l. 02, which increased about 10~ compared with that of the stoichiometric one.