Yb掺杂Ⅷ型YbxBa8-xGa16Sn30笼合物的制备及热电性能

Preparation and Thermoelectric Properties of Yb Doped Type-Ⅷ YbxBa8-xGa16Sn30 Clathrate

本研究采用Sn熔剂法成功制备出Yb掺杂Ⅷ型笼合物YbxBa8-xGa16Sn 30(0≤x≤2)热电材料,通过测试其电导率、Seebeck系数和Hall系数等分析材料的电性能,并估算其ZT值。结果表明:掺入Yb后,材料的晶格常数随Yb含量的增加而减小。x=1.5样品的电导率在整个测试温度范围内均比其余样品高,相比x=0的样品,其电导率提高了约60%,这是由于在载流子迁移率相当的情况下该样品拥有较高的载流子浓度。此外,在300~583 K范围内,样品的电导率随温度的升高而降低,表现出重掺杂半导体特性;而在583 K以后,电导率随温度的升高而增大,表现出半导体特性。在测试温度范围内(300~600 K),所有样品的Seebeck系数绝对值均随温度的升高先增大后降低。在所有样品中,x=1.5的样品具有最高的电导率,其在489 K时获得最大功率因子,为2.43×10^-3 W/(m·K^2),在此温度下其ZT值为1.35。

In this work,a successful effort was made in growing Yb-doped type-ⅧYb x Ba 8-x Ga 16 Sn 30 clathrate thermoelectric materials via a Sn-flux method.The electrical conductivity,Seebeck coefficient,and Hall coefficient of these samples were measured to analyze their electrical pro-perties,and ZT values were estimated.The results showed that the lattice constant of the material decreased with the increase of Yb content.The conductivity of the sample with x=1.5 was higher than that of other samples in the whole test temperature range,and the conductivity was improved by about 60%compared with that of the sample with x=0,which was due to higher carrier concentration when carrier mobility was comparable.In addition,the conductivity of the samples from 300 K to 583 K decreased with the increase of temperature,showing the characteristics of degenerate semiconductor.After 583 K,the conductivity increased with the increase of temperature,showing the characteristics of semiconductor.Within the test temperature range(300—600 K),the absolute value of Seebeck coefficient for all samples initially increased to a maximum value and subsequently decreased with the increase of temperature.The sample with x=1.5 obtained a large power factor with the maximum va-lue of 2.43×10^-3 W/(m·K^2)(at 489 K)due to its high conductivity,and the estimated ZT obtained a maximum value of 1.35 at 489 K.