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用EXAFS和XANES技术研究了高温固相反应法合成尖晶石结构的LiMn2 O4 中Mn原子的局域结构受到焙烧温度的影响 .XANES结果表明 ,B1 峰和B2 峰强度分别与Mn3+ ,Mn4 + 的含量高低相关 ,焙烧温度愈高 ,B1 峰的强度愈大 .EXAFS给出的结构参数结果进一步表明 ,LiMn2 O4 (6 73K)的Mn -O第一配位和Mn Mn第二配位的无序度σ1(0 .0 0 5 9nm)和σ2 (0 .0 0 92nm)分别小于及大于LiMn2 O4 (973K)的σ1 (0 .0 0 6 6nm)和σ2 (0 .0 0 81nm) ,LiMn2 O4 (10 73K)的σ1 (0 .0 0 6 4nm)和σ2 (0 .0 0 79nm) ,说明低温焙烧的LiMn2 O4 (6 73K)样品中Mn原子的局域配位环境结构与高温焙烧的LiMn2 O4 (973K)和LiMn2 O4 (10 73K)的相比有较大差异 ,前者为LiMn2 O4 和Li2 MnO3(或Li4 Mn5O1 2 )两种混合物相 ,后者为正尖晶石结构的LiMn2 O4 单一物相
EXAFS and XANES techniques were used to investigate the effect of calcination temperature on the local structure of Mn atoms in the spinel-structured LiMn2O4 synthesized by high-temperature solid-state reaction. XANES results show that the intensities of B1 and B2 peaks are similar to those of Mn3 +, Mn4 + The higher the calcination temperature, the greater the intensity of the B1 peak.The structural parameters given by EXAFS further indicate that the first coordination of Mn -O and the second coordination of Mn Mn in LiMn 2 O 4 (6 73K) Σ1 (0.0609 nm) and σ2 (0.092 nm) are less than and greater than σ1 (0.0606 nm) and σ2 (0.0800 nm) for LiMn2 O4 (973K), respectively. LiMn2O4 (10 6 0K) and σ 2 (0 0 0 79 nm) for the 1073K (1073K) samples. It is shown that the local coordination structure of Mn atoms in LiMn 2 O 4 (6 73K) sample calcined at low temperature is similar to that of high temperature calcined LiMn 2 O4 (973K) and LiMn2O4 (1073K). The former is a mixture of LiMn2O4 and Li2MnO3 (or Li4Mn5O12), and the latter is a single spinel LiMn2O4 phase