Thermoelectric Properties and Scattering Factors of Finely Grained Bi2Te3-Related Materials Prepared by Mechanical Alloying
Thermoelectric Properties and Scattering Factors of Finely Grained Bi2Te3-Related Materials Prepared by Mechanical Alloying
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DOI：
10.2320/matertrans.mh200901
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发表时间：
2010-05-01
影响因子：
1.2
通讯作者：
Noda, Yasutoshi
中科院分区：
文献类型：
--
作者：
Hasezaki, Kazuhiro;Hamachiyo, Takashi;Noda, Yasutoshi
通过机械合金化（MA）制备了名义成分为Bi 0.5Sb 1.5Tex（x = 3.0 ~ 3.4）的细晶样品。发现平均粒度范围为1.0至2.1 μ m。通过扫描电镜（SEM）、X射线衍射（XRD）和差热分析（DTA）观察到碲在x = 3.1时析出。电导率以及霍尔和塞贝克系数进行了测量，从300至470 K。使用霍尔迁移率和温度之间的关系，载流子散射因子的Bi0.5Sb1.5Tex，样品被估计为范围从r = 0.9到-2.0。在室温下，样品的热导率为0.94 ~ 1.00 Wm（-1）K（-1）。过量的碲被认为是导致热导率下降的原因。由散射因子和费米积分计算了热导率的洛仑兹数和载流子分量。在Bi_（0.5）Sb_（1.5）Tex样品中，热导率的声子成分占主导地位。Bi0.5Sb1.5Tex样品的Seebeck系数高于现有数据，这意味着Bi0.5Sb1.5Tex样品的绝对散射因子较大。Bi_（0.5）Sb_（1.5）Te_（3.1）样品在310 K时的最大优值为7.02 × 10 ~（-3）K ~（-1）。这种高品质因数是由于绝对散射因子增加而导致的增强的塞贝克系数。高热电性能，因此，可以建立由声子组分的热导率的减少，也由增强的塞贝克系数，这是从一个增加的绝对散射因子的细粒度的Bi 0.5Sb 1.5Tex样品，通过MA制备的结果。[doi：10.2320/matertrans.MH200901]
Fine grained samples with a nominal composition of Bi0.5Sb1.5Tex (x = 3.0 to 3.4) were prepared by mechanical alloying (MA). Average grain sizes were found to range from 1.0 to 2.1 mu m. Tellurium precipitation at x = 3.1 was observed by scanning electron microscopy (SEM), X-ray diffraction and differential thermal analysis (DTA). Electrical conductivity as well as Hall and Seebeck coefficients were measured from 300 to 470 K. Using the relationship between Hall mobility and temperature, carrier scattering factors of the Bi0.5Sb1.5Tex, samples were estimated to range from r = 0.9 to -2.0. The thermal conductivities of the samples were found to range from 0.94 to 1.00 Wm(-1)K(-1) at room temperature. Excess tellurium was recognized to be responsible for the decrease in thermal conductivity. The Lorenz number and the carrier component of thermal conductivity were calculated from the scattering factor and the Fermi integral. The phonon component of thermal conductivity was dominant in the Bi0.5Sb1.5Tex samples. The Seebeck coefficient of the Bi0.5Sb1.5Tex samples was higher than that from the available data which means that the absolute scattering factor of the Bi0.5Sb1.5Tex samples was large. A maximum figure of merit of 7.02 x 10(-3) K-1 was obtained at 310K for the Bi0.5Sb1.5Te3.1, sample. This high figure of merit results from an enhanced Seebeck coefficient that is due to an increased absolute scattering factor. High thermoelectric performance can, therefore, be established by a reduction in the phonon component of the thermal conductivity and also by an enhanced Seebeck coefficient, which results from an increased absolute scattering factor for finely grained Bi0.5Sb1.5Tex samples that were prepared by MA. [doi:10.2320/matertrans.MH200901]