聚乙二醇400对γ-Na_xCo_2O_4晶体形成的影响

Effects of polyethylene glycol 400 on the formation of γ-Na_xCo_2O_4 crystals

采用聚乙二醇400(PEG400)改进的柠檬酸盐溶胶-凝胶法制备氧化物热电材料γ-Na_xCo_2O_4,通过XRD和FESEM分析,研究了PEG400添加量对γ-Na_xCo_2O_4产物的相组成和形貌的影响,优化了PEG400改进柠檬酸盐溶胶-凝胶法制备γ-Na_xCo_2O_4的工艺参数。结果显示,PEG400的添加对样品的相组成和形貌均产生了明显影响。当PEG400添加量(体积分数)为1%,n(Na^+)/n(Co^(2+))为0.85~0.9,煅烧温度为800℃时,得到了单相γ-Na_xCo_2O_4晶体。当PEG400添加量(体积分数)为1%时,γ-Na_xCo_2O_4晶体为近似平行排列的片状颗粒,具有一定的取向性,颗粒分布呈现出一种三维网状结构,表明添加PEG400后,γ-Na_xCo_2O_4形成了更稳固的凝胶结构。

γ-Na_xCo_2O_4 oxide thermoelectric material was synthesized by polyethylene glycol 400（PEG400）modified citrate sol-gel method.And the effects of PEG400 on the formation of γ-Na_xCo_2O_4 crystals were studied.Through XRD and FESEM analysis,the influence of PEG400 content on phase composition and morphology of the γ-Na_xCo_2O_4 product was discussed and the processing parameters were optimized.Results show that the addition of PEG400 generates significant influence on the phase composition and morphology of the sample.Single phase γ-Na_xCo_2O_4 crystals can be formed with 1% PEG400 content（volume fraction）,Na-＋/Co-（2＋） molar ratio of 0.85-0.9,and calcination temperature of 800 ℃.The obtained crystals with certain orientation were near parallel plate-like particles and the particle distribution takes on a three dimensional network structure,indicating that γ-Na_xCo_2O_4 forms a more stable gel structure after the addition of PEG400.