The Co/CoFe2O4 multilayers have been grown on the glass substrate using sputtering techniques. In these films the Co layers were measured to have the fcc structure with [11] axis perpendicular to the film plane, and t...The Co/CoFe2O4 multilayers have been grown on the glass substrate using sputtering techniques. In these films the Co layers were measured to have the fcc structure with [11] axis perpendicular to the film plane, and the CoFe2O4 layers are amorphous. Ferromagnetic resonance measurements have been made as a function of the external magnetic field orientation in a plane perpendicular to the film. The effective magnetization, effective anisotropy constant and interface anisotropy constant have been determined. The influence of Co layers thickness on magnetic properties was discussed.展开更多
Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_...Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.展开更多
Pd/Co_(2)MnSi(CMS)/NiFe_(2)O_(4)(NFO)/Pd multilayers were fabricated on F-mica substrate by magnetron sputtering.The best PMA performance of the multilayer structure Pd(3 nm)/CMS(5 nm)/NFO(0.8 nm)/Pd(3 nm)was obtained...Pd/Co_(2)MnSi(CMS)/NiFe_(2)O_(4)(NFO)/Pd multilayers were fabricated on F-mica substrate by magnetron sputtering.The best PMA performance of the multilayer structure Pd(3 nm)/CMS(5 nm)/NFO(0.8 nm)/Pd(3 nm)was obtained by adjusting the thickness of the CMS and NFO layers.F-mica substrate has a flatter surface than glass and Si/SiO_(2) substrate.The magnetic anisotropy energy density(K_(eff))of the sample deposited on F-mica substrates is 0.6711 Merg/cm^(3)(1 erg=10^(-7) J),which is about 30%higher than that of the multilayer films deposited on glass(0.475 Merg/cm^(3))and Si/SiO_(2)(0.511 Merg/cm^(3))substrates,and the R_(Hall) and H_(C) are also significantly increased.In this study,the NFO layer prepared by sputtering in the high purity Ar environment was exposed to the high purity O_(2) atmosphere for 5 min,which can effectively eliminate the oxygen loss and oxygen vacancy in NFO,ensuring enough Co-O orbital hybridization at the interface of CMS/NFO,and thus effectively improve the sample PMA.展开更多
The magnetic properties of spinel ferrites Cu_（1-x）Zn_xFe_2O_4 are studied using high-temperature series expansions combined with the Padé approximates. The exchange interactions, inter and intra-sublattices J_...The magnetic properties of spinel ferrites Cu_（1-x）Zn_xFe_2O_4 are studied using high-temperature series expansions combined with the Padé approximates. The exchange interactions, inter and intra-sublattices J_（AA）, J_（BB） and J_（AB） are obtained using a probability distribution law. The critical exponent associated with the magnetic susceptibility is obtained.展开更多
文摘The Co/CoFe2O4 multilayers have been grown on the glass substrate using sputtering techniques. In these films the Co layers were measured to have the fcc structure with [11] axis perpendicular to the film plane, and the CoFe2O4 layers are amorphous. Ferromagnetic resonance measurements have been made as a function of the external magnetic field orientation in a plane perpendicular to the film. The effective magnetization, effective anisotropy constant and interface anisotropy constant have been determined. The influence of Co layers thickness on magnetic properties was discussed.
基金supported by the Special Project for the Central Government to Guide Local Technological Development (GUIKE ZY20198008)the Guangxi Technology Base and talent Subject (GUIKE AD20238012,AD20297086)+5 种基金the Natural Science Foundation of Guangxi Province (2021GXNSFDA075012)the National Natural Science Foundation of China (51902108,52104298,22169004)the National Natural Science Foundation of China (U20A20249)the Regional Innovation and Development Joint Fundthe Guangxi Innovation Driven Development Subject (GUIKE AA19182020,19254004)the Special Fund for Guangxi Distinguished Expert。
文摘Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.
文摘Pd/Co_(2)MnSi(CMS)/NiFe_(2)O_(4)(NFO)/Pd multilayers were fabricated on F-mica substrate by magnetron sputtering.The best PMA performance of the multilayer structure Pd(3 nm)/CMS(5 nm)/NFO(0.8 nm)/Pd(3 nm)was obtained by adjusting the thickness of the CMS and NFO layers.F-mica substrate has a flatter surface than glass and Si/SiO_(2) substrate.The magnetic anisotropy energy density(K_(eff))of the sample deposited on F-mica substrates is 0.6711 Merg/cm^(3)(1 erg=10^(-7) J),which is about 30%higher than that of the multilayer films deposited on glass(0.475 Merg/cm^(3))and Si/SiO_(2)(0.511 Merg/cm^(3))substrates,and the R_(Hall) and H_(C) are also significantly increased.In this study,the NFO layer prepared by sputtering in the high purity Ar environment was exposed to the high purity O_(2) atmosphere for 5 min,which can effectively eliminate the oxygen loss and oxygen vacancy in NFO,ensuring enough Co-O orbital hybridization at the interface of CMS/NFO,and thus effectively improve the sample PMA.
文摘The magnetic properties of spinel ferrites Cu_（1-x）Zn_xFe_2O_4 are studied using high-temperature series expansions combined with the Padé approximates. The exchange interactions, inter and intra-sublattices J_（AA）, J_（BB） and J_（AB） are obtained using a probability distribution law. The critical exponent associated with the magnetic susceptibility is obtained.
