Comparative Studies on Structure and Electronic Properties Between Thermal Lithiated Li0.5MnO2 and LiMn2O4

Monoclinic Li0.5MnO2 was synthesized by solid state reaction and the spectral and magnetic properties were studied in comparison with those of spinel LiMn2O4.The XRD pattern and Raman spectrum of Li0.5MnO2 are different from those of LiMn2O4,which indicate the different long-range and short-range crystal structure.XPS result shows the binding energies of 2p3/2 and 2p1/2 in Li0.5MnO2 are located at 642.3 and 653.6 eV,respectively.Through fitting the XPS spectra,the valence state of Mn ion in Li0.5MnO2 coincides with that in LiMn2O4.The high-temperature susceptibility of Li0.5MnO2 can be fitted by Curie-Weiss law whose Curie and Weiss constants are 33 A·m2·K/(mol·T) and-277(6) K,respectively.Although Li0.5MnO2 shows spin glass ground state,the transition temperature of Li0.5MnO2 is about 9 K lower than that of LiMn2O4.