Ca^(2+)掺杂对CdO多晶热电性能的影响  

High temperature thermoelectric performance of Ca^(2+) doped CdO ceramics

作　　者：刘冉[1] 高琳洁[1] 李龙江[1] 翟胜军[1] 王江龙[1] 傅广生[1] 王淑芳[1] 

机构地区：[1]河北省光电信息材料重点实验室,河北大学物理科学与技术学院,保定071002

出　　处：《物理学报》2015年第21期419-425,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51372064);河北省杰出青年科学基金(批准号:2013201249)资助的课题~~

摘　　要：以CaCO3作为Ca2+源,利用传统固相烧结法制备了Cd1-xCaxO(x=0,0.01,0.03,0.05)多晶块体样品并研究了Ca2+掺杂对CdO高温热电性能的影响.CaCO3的掺入会导致CdO多晶载流子浓度降低,使Cd1-xCaxO的电阻率ρ和塞贝克系数的绝对值|S|增大、电子热导率κe减小.同时,在CdO中掺入CaCO3会引入点缺陷和气孔并可抑制CdO晶粒长大、晶界增多,从而增加了对声子的散射,使样品的声子热导率κp减小.由于总热导率的大幅降低,Cd0.99Ca0.01O多晶样品在1000 K时的热电优值ZT可达0.42,比本征CdO提高了约27%,为迄今n型氧化物热电材料报道的最好结果之一.Oxide thermoelectric materials have been considered to be potential candidates in high-temperature thermoelectric power generation, however, their high thermal conductivity renders them inferior to the conventional thermoelectric materials and limit their practical application. In this paper, we successfully reduce the thermal conductivity of Cd O polycrystals through Ca2＋doping, and the improvement in ZT is also obtained due to the low thermal conductivity.Cd1-xCaxO（x = 0, 0.01, 0.03, 0.08） polycrystals are synthesized by adding CaCO3 into CdO via conventional solidstate reaction method and their high-temperature thermoelectric properties are studied. XRD results reveal that all samples are composed of CdO polycrystals, and the lattice parameters increase with Ca2＋content due to the larger radius of Ca2＋as compared with that of Cd2＋. Addition of CaCO3 can induce the formation of point defects as well as pores in the CdO polycrystals, thus inhibits the grain growth of Cd O and induces the increase of grain boundaries.The main electron carriers in CdO are reported to be shallow level donor impurities formed by oxygen vacancies; as the Ca2＋concentration in Cd1-xCaxO increases, the conduction band minimum of the samples shifts upward and the level of donor impurity becomes deeper, finally resulting in the decrease of electron carrier concentration. Meanwhile,the reduced carrier concentration in the doped samples leads to the increase of both the electrical resistivity ρ and the absolute Seebeck coefficient ｜S｜, while the electrical thermal conductivity κe will decrease with increasing Ca content.Investigations on the thermal properties of the obtained samples demonstrate that the introduction of Ca2＋is effective to suppress the thermal conductivity. The increment of pores and grain boundaries in the doped samples will enhance the long-wavelength phonon scattering, resulting in the decrease of phonon thermal conductivity κp. Furthermore, the point defects, which come from the mass and size diff

关 键 词：热电 CdO多晶 热导率 ZT 

分 类 号：TB34[一般工业技术—材料科学与工程]