制备条件对尖晶石型LiMn2O4的相行为及结构的影响

将LiNO₃和Mn₃O₄按不同物质的量比[x=n(Li):n(Mn)=0.50,0.52,0.54,0.58,0.62,0.70]混合,在空气气氛下,于700℃烧结得样品.实验发现,在0.52≤x≤0.70的范围内,样品均呈现出单相的尖晶石型LiMn₂O₄结构,晶胞参数随着x的增加而减小.将x=0.50的LiNO₃和Mn₃O₄混合物在不同温度(300,400,500,600和700℃)下进行烧结处理.结果表明,于300℃合成得到的样品为尖晶石型LiMn₂O₄,随着烧结温度的升高,晶胞参数增大;当温度大于600℃时出现杂相,可以通过加入过量的Li(即x≥0.52)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LiMn₂O₄单相材料.

Effect of Preparation Condition on Phase Behavior and Structure of Spinel LiMn2O4

Mixtures of LiNO₃ and Mn₂O₃, with different n(Li)/n(Mn) ratios[x=n(Li): n(Mn)=0.50, 0.52, 0.54, 0.58, 0.62 and 070], were sintered at 700 ℃. It is found that materials with x ratio between₀ 52 and 0.70 exhibit a single phase spinel structure. Lattice constant decreases with the increase of x value. The mixture of LiNO₃ and Mn₂O₃, 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.