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本文以CaCO3、NaF、Co(NO3)2.6H2O、HNO3为原料,去离子水为溶剂,柠檬酸为螯合剂,采用自蔓延法制备了NaF掺杂的Ca3Co4O9(Ca3-xNaxCo4O9-xFx)(x=0,0.05,0.1,0.15,0.2,0.25)粉体。粉末的XRD表明图谱中主要衍射峰是Ca3Co4O9的特征峰,有极小部分CaF2存在。粉体的粒度分布在1～100μm之间,平均粒径为11.276μm。烧结试样的SEM显示NaF的掺杂能促进烧结。在温度473～973K下,烧结体热电性能的测试结果显示,随NaF掺杂量的增加,电导率和Seebeck系数先升高后降低。加入20%NaF的Ca3Co4O9烧结体在973K时seebeck系数和功率因子达到最大值,分别为220μV/K和4.39×10-4 W/mK2。
In this paper, NaF doped Ca3Co4O9 (Ca3-xNaxCo4O9-xFx) was prepared by self-propagating method using CaCO3, NaF, Co (NO3) 2.6H2O and HNO3 as raw materials, deionized water as solvent and citric acid as chelating agent, 0,0.05,0.1,0.15,0.2,0.25) powder. XRD analysis of the powder shows that the main diffraction peak in the spectrum is the characteristic peak of Ca3Co4O9, and a very small part of CaF2 exists. The particle size distribution of the powder is between 1 and 100 μm and the average particle size is 11.276 μm. SEM of the sintered samples shows that the doping of NaF can promote sintering. The thermoelectric properties of the sintered samples at 473K to 973K showed that the conductivity and Seebeck coefficient increased first and then decreased with the increase of NaF doping content. The seebeck coefficient and power factor reached the maximum at 973K with 220μV / K and 4.39 × 10-4 W / mK2, respectively, for Ca3Co4O9 sintered with 20% NaF.