NaCo_2O_4陶瓷微观结构对其电性能的影响

Effect of Microstructure on the Electric Properties of NaCo_2_O4 Ceramics

采用自助熔剂法制备NaCo2O4多晶粉体、经单向加压和冷等静压两种不同的方式压片后烧结获得NaCo2O4陶瓷,观察并分析其物相和微观形貌,测试其电性能,研究NaCo2O4晶粒择优取向度和相对密度对其电性能的影响。结果表明,样品的择优取向度和相对密度越高,其电导率和功率因子也越高。Na∶Co=0.7∶1经单向加压的试样较其它试样具有更高的择优取向度和相对密度。其电导率在303K时达到最大值4.2×104S·m-1,功率因子在823K时达到最大值450μW·m-1·K-2。

Na Co2O4 polycrystalline powders were synthesized by self-flux method,and then ceramic samples were prepared by two methods of uniaxial pressing and cold isostatic pressing. Phases and micromorphology analysis as well as its electric properties were observed. The impacts of grain preferred orientation and relative density of Na Co2O4 ceramics on electric properties were investigated accordingly.As a result,a higher electrical conductivity and power factor of sample are caused by its higher preferred orientation degree and relative density. The sample of Na∶ Co = 0. 7∶ 1 with uniaxial pressure is proved to have a higher preferred orientation degree and relative density comparatively. Meanwhile,it can be observed that electrical conductivity reaches to a maximum value of 4. 2 × 10^4S·m^- 1at 303 K,and a maximum value of power factor equals to 450 μW·m^- 1·K^- 2at 823 K.