Cu掺杂AgSbTe2化合物的相稳定、晶体结构及热电性能  

Phase stability,crystal structure and thermoelectric properties of Cu doped AgSbTe_2

作　　者：张贺[1,2] 骆军[2] 朱航天[1,2] 刘泉林[1] 梁敬魁[2] 饶光辉[2] 

机构地区：[1]北京科技大学材料科学与工程学院,新金属材料国家重点实验室,北京100083 [2]中国科学院物理研究所,北京100190

出　　处：《物理学报》2012年第8期313-319,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11144002);国家重点基础研究发展计划(批准号:2007CB925003);教育部科学技术研究计划重大项目(批准号:309006)资助的课题~~

摘　　要：利用熔融快淬结合放电等离子烧结(SPS),制备了Cu_xAg_(1-x)SbTe_2(x=0—0.3)样品.粉末X射线衍射(XRD)分析结果显示,SPS处理以前,含Cu样品形成NaCl型结构的固溶体,而未加入Cu的样品析出Ag_2Te第二相.根据热分析和XRD测量结果,Cu的加入能够有效抑制Ag_2Te的析出,但同时会在快淬样品中产生少量非晶相.在温度升高到540 K左右时,非晶相发生晶化,形成Sb_7Te亚稳相,并最终转变成Sb_2Te_3稳定相.对快淬样品进行低温SPS快速处理后,x=0.1样品为面心立方结构的单相化合物,但是x=0.2,0.3的样品分别析出第二相Sb_7Te和Sb_2Te_3.由于析出第二相,x=0.2,0.3样品的电导率增大,Seebeck系数减小,热导率相应升高,综合热电性能降低.x=0.1单相样品的功率因子与文献报道的AgSbTe_2化合物相当.元素替代的合金化效应增强了Cu_(0.1)Ag_(0.9)SbTe_2化合物的声子散射,有效降低了样品的热导率.因此,单相样品Cu_(0.1)Ag_(0.9)SbTe_2表现出较佳的热电性能,在620 K时热电优值达到1.CuxAgl-zSbTe2 samples with x = 0-0.3 are prepared by a combined process of melt-quenclamg and spark plasma smtenng （SPS）. X-ray powder diffraction （XRD） analysis indicates that single phase samples with the NaCl-type structure are obtained for the Cu-doped samples before SPS treatment, whereas a small quantity of AgaTe impurities coexist with the main cubic phase for the sample without Cu. According to our thermoanalysis and XRD results, the substitution of Cu for Ag can effectively prevent the precipitation of AgzTe, but this also leads to the presence of a minor amorphous phase in the melt-quenched sample. The amorphous phase crystallizes into SbTTe metastable phase at about 540 K, which finally transforms into the stable Sb2Te3 compound. After the SPS treatment of the melt-quenched sample, the sample with x = 0.1 remains a single phase with the face-centered-cubic crystal structure, while SbTTe andSb2Tea are precipitated as the second phases for the samples with x = 0.2 and 0.3, respectively. The electrical conductivity increases and the Seebeck coefficient decreases with the addition of Cu due to the existence of the second phase in the samples with x = 0.2 and 0.3. Accordingly, thermal conductivities also increase with the addition of Cu, leading to the reduced thermoelectric performance of the x = 0.2 and 0.3 samples. For the sample with x = 0.1, its power factor is comparable to that of the literature reported AgSbTe2 compound. As a result of so-called alloying effect, the phonon scattering effect is enhanced due to the partial replacement of Ag by Cu, leading to the reduced thermal conductivity of the x = 0.1 sample. Therefore, the CuoaAgo.gSbTe2 sample exhibits the promising thermoelectric performance and a dimensionless thermoelectric figure of merit （ZT） value of 1 is achieved at 620 K.

关 键 词：AgSbTe2 相稳定 晶体结构 热电性能 

分 类 号：O482[理学—固体物理]