烧结温度对La_(0.1)Sr_(0.9)TiO_3陶瓷热电性能的影响

Influence of sintering temperature on thermoelectric properties of La_(0.1)Sr_(0.9)TiO_3 ceramics

利用传统固相反应方法,分别在1440°C,1460°C,1480°C和1500°C烧结条件下,制备了钙钛矿结构的La_(0.1)Sr_(0.9)TiO_3陶瓷样品.样品的粉末X射线衍射结果显示,不同烧结温度的La_(0.1)Sr_(0.9)TiO_3陶瓷样品均为单相的正交结构.从样品的扫描电子显微照片来看,随着烧结温度的增加,平均晶粒尺寸逐渐增大.在室温至800°C的测试温区,测试了样品的电阻率和Seebeck系数,系统地研究了不同烧结温度对样品热电性能的影响.结果表明,样品的电阻率在测试温区内随着测试温度的升高先略微降低,然后逐渐升高;总体来看,样品的电阻率随烧结温度的升高先增大后降低.在测试温区内,Seebeck系数均为负值,表明样品的载流子为电子;随着测试温度的升高,Seebeck系数绝对值均有所增大;随烧结温度升高,Seebeck系数绝对值逐渐增大后显著降低.1480°C制备的样品因其相对较低的电阻率和相对较高的Seebeck系数绝对值,在165°C时得到最大的功率因子21μW·K^(-2).cm^(-1).

Ceramic samples of La0.1Sr0.9TiO3 are synthesized by conventional solid state reaction technique at 1440℃, 1460 ℃, 1480 ℃ and 1500 ℃, respectively. Their thermoelectric properties are investigated. X-ray diffraction characterization confirms that the main crystal structure is of perovskite. Scanning electron microscope images indicate that all ceramic samples are dense and compact, and that the average grain size increases with the increase of sintering temperature. Electrical resistivity and Seebeck coefficient of samples are measured in the temperature range between room temperature and 800℃. In general, with the increase of sintering temperature, the electrical resistivity first increases, and then decreases. With the increase of sintering temperature, the absolute Seebeck coefficient first increases, and then decreases. A maximal power factor 21 uW.K-2.cm-1 is obtained at 165 ℃ for the sample sintered at 1480 ℃ because of its reletivly high absolute Seebeck coefficient and reletively low electrical resistivity.