制备条件对尖晶石型LiMn_2O_4的相行为及结构的影响

Effect of Preparation Condition on Phase Behavior and Structure of Spinel LiMn_2O_4

将 Li NO3和 Mn3O4 按不同物质的量比 [x=n(Li)∶n(Mn) =0 .5 0 ,0 .5 2 ,0 .5 4,0 .5 8,0 .62 ,0 .70 ]混合 ,在空气气氛下 ,于 70 0℃烧结得样品 .实验发现 ,在 0 .5 2≤ x≤ 0 .70的范围内 ,样品均呈现出单相的尖晶石型 Li Mn2 O4 结构 ,晶胞参数随着 x的增加而减小 .将 x=0 .5 0的 Li NO3和 Mn3O4 混合物在不同温度(3 0 0 ,40 0 ,5 0 0 ,60 0和 70 0℃ )下进行烧结处理 .结果表明 ,于 3 0 0℃合成得到的样品为尖晶石型 Li Mn2 O4 ,随着烧结温度的升高 ,晶胞参数增大 ;当温度大于 60 0℃时出现杂相 ,可以通过加入过量的 Li(即 x≥ 0 .5 2 )来加以抑制 .实验结果表明 ,通过控制烧结温度和 Li加入量可以得到理想的尖晶石型 Li Mn2 O4 单相材料 .

Mixtures of LiNO 3 and Mn 2O 3, with different \%n\%(Li)/\%n\%(Mn) ratios[ x=n (Li)∶ n (Mn)=0 50, 0 52, 0 54, 0 58, 0 62 and 0 70], were sintered at 700 ℃. It is found that materials with x ratio between 0 52 and 0 70 exhibit a single phase spinel structure. Lattice constant decreases with the increase of x value. The mixture of LiNO 3 and Mn 2O 3, with x =0 50, was sintered at different temperatures(300, 400, 500, 600 and 700 ℃). The results show that the materials sintered at temperature lower than 600 ℃, additional phase can be removed via over adding the lithium to extend x value larger than 0 52. Lattice constant increases with increasing the sintering temperature.