Superfine powders of nano-lithium ferrite doped with different kinds and amount of rare earth element were prepared by sol-gel method. Their photograph was taken by transmission electron microscopy. From it, we can se...Superfine powders of nano-lithium ferrite doped with different kinds and amount of rare earth element were prepared by sol-gel method. Their photograph was taken by transmission electron microscopy. From it, we can see most of particles are less than 100 nm and average diameter of superfine powders is 50 nm. Then their microwave absorption properties are measured by power ratio method. The result indicates that microwave absorption properties of nano-lithium ferrite doped with rare earth element change obviously. Different kinds and amount of rare earth element make different influences. Magnetic hysteresis loop is surveyed by vibrating sample magnetometer. We find that there are some relationships between magnetism and microwave absorption properties.展开更多
This article conducts first-principles calculations to initially explore the construction of two configurations,NaFeO_(2)(NFO)and NaMnO_(2)(NMO),and studies the mixing enthalpies under different Fe–Mn ratios.The resu...This article conducts first-principles calculations to initially explore the construction of two configurations,NaFeO_(2)(NFO)and NaMnO_(2)(NMO),and studies the mixing enthalpies under different Fe–Mn ratios.The results indicate that NaFe_(3/8)Mn_(5/8)O_(2)(NFMO)exhibits the most thermodynamically stable structure.Subsequent calculations on the mixing enthalpies and volume changes during the sodium extraction process for NFO,NMO,and NFMO configurations are presented,along with the partial density of states(PDOS)and Bader charges of transition metals(TM)and oxygen.These calculations reveal the synergistic mechanism of Fe and Mn.Fe and Mn can engage in more complex electron exchanges during sodium extraction,optimizing the internal electron density distribution and overall charge balance,thereby stabilizing the crystal structure and reducing the migration of Fe^(3+)to the sodium layers during deep sodium extraction.The interaction between Fe’s 3d electrons and Mn’s 3d electrons through the shared oxygen atoms’2p orbitals occurs in the Fe–Mn–O network.This interaction can lead to a rebalancing of the electron density around Mn³⁺atoms,mitigating the asymmetric electron density distribution caused by the d4 configuration of the lone Mn³⁺and suppressing the Jahn-Teller effect of Mn^(3+).Moreover,the synergistic effects between Fe and Mn can provide a more balanced charge distribution,reducing extreme changes to the charge state of oxygen atoms and decreasing the irreversible oxygen release caused by anionic redox reactions during deep sodium extraction,thereby enhancing the material’s stability.This in-depth study of the interaction mechanism at the microscopic level when co-doping Fe and Mn offers valuable insights for the rational design and development of high-performance cathode materials.展开更多
文摘Superfine powders of nano-lithium ferrite doped with different kinds and amount of rare earth element were prepared by sol-gel method. Their photograph was taken by transmission electron microscopy. From it, we can see most of particles are less than 100 nm and average diameter of superfine powders is 50 nm. Then their microwave absorption properties are measured by power ratio method. The result indicates that microwave absorption properties of nano-lithium ferrite doped with rare earth element change obviously. Different kinds and amount of rare earth element make different influences. Magnetic hysteresis loop is surveyed by vibrating sample magnetometer. We find that there are some relationships between magnetism and microwave absorption properties.
文摘This article conducts first-principles calculations to initially explore the construction of two configurations,NaFeO_(2)(NFO)and NaMnO_(2)(NMO),and studies the mixing enthalpies under different Fe–Mn ratios.The results indicate that NaFe_(3/8)Mn_(5/8)O_(2)(NFMO)exhibits the most thermodynamically stable structure.Subsequent calculations on the mixing enthalpies and volume changes during the sodium extraction process for NFO,NMO,and NFMO configurations are presented,along with the partial density of states(PDOS)and Bader charges of transition metals(TM)and oxygen.These calculations reveal the synergistic mechanism of Fe and Mn.Fe and Mn can engage in more complex electron exchanges during sodium extraction,optimizing the internal electron density distribution and overall charge balance,thereby stabilizing the crystal structure and reducing the migration of Fe^(3+)to the sodium layers during deep sodium extraction.The interaction between Fe’s 3d electrons and Mn’s 3d electrons through the shared oxygen atoms’2p orbitals occurs in the Fe–Mn–O network.This interaction can lead to a rebalancing of the electron density around Mn³⁺atoms,mitigating the asymmetric electron density distribution caused by the d4 configuration of the lone Mn³⁺and suppressing the Jahn-Teller effect of Mn^(3+).Moreover,the synergistic effects between Fe and Mn can provide a more balanced charge distribution,reducing extreme changes to the charge state of oxygen atoms and decreasing the irreversible oxygen release caused by anionic redox reactions during deep sodium extraction,thereby enhancing the material’s stability.This in-depth study of the interaction mechanism at the microscopic level when co-doping Fe and Mn offers valuable insights for the rational design and development of high-performance cathode materials.
