Bi掺杂对La_(0.1)Sr_(0.9)TiO_3陶瓷热电性能的影响

Effects of Bi Doping on Thermoelectric Properties of La_(0.1)Sr_(0.9)TiO_3 Ceramics

在5%H_2+95%N_2(V/V)还原气氛中1 500℃烧结4 h制备La_(0.1)Bi_xSr_(0.9-x)TiO_3(x=0、0.05、0.075、0.1)陶瓷,并对其组成、显微结构和热电性能进行研究。结果表明:掺Bi试样的主晶相均为Sr Ti O3,当Bi掺杂量大于0.075时,样品中出现少量Bi_2O_3杂相;掺Bi试样的晶粒发育完全,形状规则,结合紧密,显示出Bi_2O_3良好的助烧效果。另外,Bi元素掺入使La_(0.1)Sr_(0.9)TiO_3陶瓷的电导率和Seebeck系数绝对值显著增加,说明Bi元素的掺入可有效提高材料的载流子浓度和载流子迁移率。其中,x=0.075时试样的功率因子最大,在400℃时为692μW·m^(-1)·K^(-2)。虽然其热导率比未掺杂Bi试样有所提高,x=0.075时试样的ZT值在500℃时仍可达0.172,比未掺杂Bi试样提高了130%。

La0.1BixSr0.9-xTiO3（x=0, 0.05, 0.075, 0.1） ceramics were fabricated at 1 500℃ for 4 h in 5%H2＋95%N2（V/V） reduction atmosphere. The phase composition, microstructure and thermoelectric properties were investigated. The results indicated that the main phase of the samples doped with Bi was SrTiO3, and trace Bi2O3 was observed when the Bi doping content is more than 0.075. The grain of the samples doped with Bi was fully developed, regularly shaped and combined closely, suggesting the good sintering effect of Bi2O3. Moreover, the electric conductivity and the absolute Seebeck coefficient of La0.1Sr0.9TiO3 ceramics increased obviously with the doping of Bi, indicating that the carrier concentration and carrier mobility were greatly improved by the Bi doping. The power factor of the sample with x=0.075 was maximum, which attained 692 μW·m^-1·K^-2 at 400℃. Though the thermal conductivity of the samples doped with Bi was higher than that of the sample without Bi, the ZT value of the sample with x=0.075 could still reach 0.172 at 500℃, which was increased by 130% compared with that of the sample without Bi.