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 differ...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·m^2.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.展开更多
A typical Li＋ substituted NiO compound, Li0.29Ni0.710, was synthesized by molten nitrate method. The ef- fects of Li＋ substitution on the structure and magnetic properties of NiO were investigated. X-Ray diffraction...A typical Li＋ substituted NiO compound, Li0.29Ni0.710, was synthesized by molten nitrate method. The ef- fects of Li＋ substitution on the structure and magnetic properties of NiO were investigated. X-Ray diffraction（XRD）, scanning electron microscope（SEM） and high-resolution transmission electron microscope（HRTEM） analyses con- firm the cubic structure of Li0.29Ni0,710, with a primary particle size of 150 nm. Analysis of the Ni X-ray photoelec- tron spectroscopy（XPS） shows the transformation from Ni2. to Ni3＋ induced by Li＋ substitution. Two magnetic tran- sitions were observed at 225 and 55 K which were assigned to the ferrimagnetic ordering and spin glass transition, respectively. The different magnetic behavior with respect to that of NiO was attributed to the break of superexchange interaction Ni2＋-O-Ni2＋ and the formation of different spin clusters after non-magnetic Li＋ doping.展开更多
基金Supported by the National Natural Science Foundation of China(No.50672031)the Special Funds for Major State Basic Research Project of China(No.2009CB220104)+1 种基金Program for Changjiang Scholar and Innovative Research Team in Universities of China(No.IRT0625)Jilin Province Project of Research and Development,China(Nos.20060511 and 20075007)
文摘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·m^2.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.
基金Supported by the Special Funds for Major National Basic Research Project of China（No.2009CB220104）, the National Natural Science Foundation of China（No. 11004073） and the Research Fund for the Doctoral Program of Higher Education of China（New Teacher）（No.20090061120020） and Partially Supported by the Development Program of Science and Technology of Jilin Province, China（No.201205035）.
文摘A typical Li＋ substituted NiO compound, Li0.29Ni0.710, was synthesized by molten nitrate method. The ef- fects of Li＋ substitution on the structure and magnetic properties of NiO were investigated. X-Ray diffraction（XRD）, scanning electron microscope（SEM） and high-resolution transmission electron microscope（HRTEM） analyses con- firm the cubic structure of Li0.29Ni0,710, with a primary particle size of 150 nm. Analysis of the Ni X-ray photoelec- tron spectroscopy（XPS） shows the transformation from Ni2. to Ni3＋ induced by Li＋ substitution. Two magnetic tran- sitions were observed at 225 and 55 K which were assigned to the ferrimagnetic ordering and spin glass transition, respectively. The different magnetic behavior with respect to that of NiO was attributed to the break of superexchange interaction Ni2＋-O-Ni2＋ and the formation of different spin clusters after non-magnetic Li＋ doping.
