【摘要】 采用溶胶凝胶及冷压方法,通过在Ca₃Co_3.9Cu_0.1O_9-δ体系中引入不同量的Ag⁺或Yb³⁺离子来调控体系的热电性能,制备了可在300⁸80 K下稳定存在且热电性能优良的陶瓷材料Ca_3-xAg_xCo_3.9Cu_0.1O_9-δ（x=0.1,0.15,0.2,0.3）和Ca_3-yYb_yCo_3.9Cu_0.1O_9-δ（y=0.05,0.1,0.2,0.3）.通过X射线衍射（XRD）和扫描电子显微镜（SEM）等测试手段对产物进行了表征,结果显示所制备的样品纯度较高,晶粒均匀,晶粒间较致密.适量的Ag⁺,Yb³⁺离子取代Ca²⁺离子固溶到晶体中使制备的双掺杂材料晶胞体积发生了变化,但并未引起晶体对称结构的变化.电阻率和Seebeck系数的表征结果说明双掺杂优化了载流子的浓度,随着温度的升高电阻率不断减小,Seebeck系数不断增大.经过计算可知Seebeck系数的增大还有电子有效质量的贡献.热导率表征结果显示双掺杂体系的热导率随着温度的升高而减小,其中声子热导依然起主要作用,这与单掺杂体系的结果一致.随着温度的升高,双掺杂样品Ca_2.7Ag_0.3Co_3.9Cu_0.1O_9-δ在880 K下ZT值达到最大,为0.2.更多还原

【Abstract】 A series of ceramic materials Ca_3-xAg_xCo_{3. 9}Cu_{0. 1}O_9-δ（ x = 0. 1,0. 15,0. 2,0. 3） and Ca_3-yYb_yCo_{3. 9}Cu_{0. 1}O_9-δ（ y = 0. 05,0. 1,0. 2,0. 3） which worked from 300 K to 880 K with excellent thermoelectric properties was prepared via sol-gel and cold-pressing method. The XRD results and SEM images revealed that the prepared samples are uniform crystal particles with high purity. Ag+and Yb³⁺ ions have replaced the position of Ca²⁺ions and they are dissolved in the crystal,which changes the cell volume of the dual doping materials but does not change the crystal symmetric structure. The resistivity and Seebeck coefficient of the materials reveal that the concentration of the current carrier is optimized by dual doping,accordingly the resistivity decreases continuously and the value of Seebeck coefficient increases continuously with the increase of temperature. It can be concluded from the calculations that the effective mass of the electron contributes to the increase of Seebeck coefficient. The thermal conductivity of dual doped samples decreases with the increase of temperature,and the phonon thermal conductivity still contributes more in the prepared system,which is consistent with the results of single doped samples. The figure of merit ZT of Ca_{2. 7}Ag_{0. 3}Co_{3. 9}Cu_{0. 1}O_9-δ reaches 0.2 at 880 K.更多还原