溶胶-凝胶法制备γ-Na_xCo_2O_4热电材料及其电性能

Preparation and Electric Transport Properties of γ-Na_xCo_2O_4 Thermoelectric Material by Sol-gel Method

采用柠檬酸盐溶胶-凝胶法合成了-γNaxCo2O4粉体,通过放电等离子烧结技术(SPS)制备了致密块体γ-NaxCo2O4材料。探讨了Na/Co摩尔比和煅烧温度对产物相组成的影响,研究了-γNaxCo2O4块体材料的电性能。结果表明,Na/Co摩尔比和煅烧温度都对产物相组成产生了显著影响,Na/Co摩尔比和煅烧温度的增加都促进了γ-NaxCo2O4晶相的形成,合适的Na/Co摩尔比和煅烧温度分别为0.74和750—900℃。800℃放电等离子烧结后,得到了致密的块体材料,材料在900 K时其Seebeck系数为165μV/K,功率因子达388μW/mK2。

У-NaxCo2O4 powders were synthesized by citric acid sol-gel method and sintered by spark plasma sintering. The effects of Na/Co mole ratio and calcination temperature on the phase composition of products were researched. The electric properties of the bulk material were also determined. The results show that the increases of Na/Co mole ratio and calcination temperature all advance the formation of У-NaxCo2O4 phase. The proper Na/Co mole ratio and calcination temperature are 0.74 and 750--900℃ respectively. The seebeck coefficient and power factor of the bulk material at 800 ℃ by SPS are 165 μV/K and 388μW/mK^2 at 900 K respectively.