Ferrite compound Co0.6Zn0.4NixFe2-xO4 was synthesized by solid state reaction. The structure and performance of Co0.6Zn0.4NixFe2-xO4 compounds were studied by Moessbauer spectroscopy, X-ray diffraction （XRD）, X-ray ...Ferrite compound Co0.6Zn0.4NixFe2-xO4 was synthesized by solid state reaction. The structure and performance of Co0.6Zn0.4NixFe2-xO4 compounds were studied by Moessbauer spectroscopy, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and infrared radiant tester. Moessbauer spectroscopy and XPS analysis show the valence states and distribution of cations in Co0.6Zn0.4NixFe2-xO4. Zn2＋ has invariably shown preference for the tetrahedral sites, and Ni2＋ has the preference for the octahedral sites. The occupancy of Fe3＋ linearly increases on the tetrahedral sites, and sharply decreases on the octahedral sites with increasing x, owing to its gradual replacement by Ni2＋ on the octahedral sites. It indicates that due to the occupation of octahedral sites by the majority of Ni2＋, Fe3＋ decreasingly migrated from the octahedral sites to the tetrahedral sites and substituted Co3＋ sites, which made the number of Co3＋ in the tetrahedral sites decreasing. According to the measurement results of XRD and the infrared radiant tester analysis, the lattice parameter and infrared radiance have shown a nonlinear variation, exhibiting the infrared average radiance of 0.92 in the 8-14μm waveband, and the results demonstrate that these Co-Zn-Ni spinel ferrites have potential for application in a wide range of infrared heating and drying materials.展开更多
The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 all...The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 alloy, inhomogeneous in the as-quenched state, crystallized after annealing at 948 K for 0.5 h and consisted of Nd2Fe14B-type, Fe2B and paramagnetic phases. The rapidly solidified Fe64Co5Nd6Y6B19 alloy contained the Nd2Fel4B-type and paramagnetic phases. The annealing of the bulk Fe67CosNd3Y6B19 alloy at 948 K for 0.5 h led to hard magnetic properties. However, the bulk Fe64Co5Nd6Y6B19 alloy exhibited good hard magnetic properties directly after preparation.展开更多
The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscop...The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscopy measurements at room temperature. From the analysis of the Moessbauer spectra, it is observed that s-electron density, electric field gradient （EFG）, quadrupole coupling constant （QCC） and the net hyperfine magnetic fields acting on the Moessbauer nuclei-FeA^3＋ and FeB^3＋ change with the increase of Ti^4＋ doping in Mg0.95Mn0.05Fe2O4. The hyperfine magnetic field decreases with the increase of Ti^4＋ doping.展开更多
The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbaue...The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.展开更多
The ideal formula for chevkinite can be expressed as A4BC2D2Si4O22. It is important to determine the valence state and site occupation proportions for Fe among the B, C, and D octahedral sites as it may help to identi...The ideal formula for chevkinite can be expressed as A4BC2D2Si4O22. It is important to determine the valence state and site occupation proportions for Fe among the B, C, and D octahedral sites as it may help to identify different species in the chevkinite group. Non-metamict chevkinite-（Ce） from Mianxi alkali feldspar-granite, Sichuan Province, China, was investigated using Moessbauer spectroscopy. The Fe^3＋/∑Fe ratio was 39.2%. A significant increase of Fe^3＋ occured during metamictization and annealing for chevkinite-group minerals. In metamict samples Fe tended to lower coordination, According to the correlation between bond length and isomer shift （IS）, the quadrupole doublets with IS = 1.10 and 0.94 mm·s^-1 can be assigned to Fe^2＋ in the B and C octahedral sites, respectively. Based on the correlation between octahedral distortion and quadrupole splitting （QS）, the quadrupole doublets with QS = 0.86 and 0.77 mm·s^-1 can be assigned to Fe^3＋ in the C and D sites, respectively. The simplified formula can be revised as： Ce4Fe^2＋ （Ti, Fe^2＋, Fe^3＋ ）2（Ti, Fe^3＋ ）2Si4（O,OH）22. It indicated that the non-metamict chevkinite-（Ce） belonged to Fe^2＋ end member of the chevkinite group because Fe^2＋ was the predominant component in the B site.展开更多
基金supported by the Key Project in Science and Technology Innovation Cultivation Program of Soochow University,China (Contract No.Q3109808)
文摘Ferrite compound Co0.6Zn0.4NixFe2-xO4 was synthesized by solid state reaction. The structure and performance of Co0.6Zn0.4NixFe2-xO4 compounds were studied by Moessbauer spectroscopy, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and infrared radiant tester. Moessbauer spectroscopy and XPS analysis show the valence states and distribution of cations in Co0.6Zn0.4NixFe2-xO4. Zn2＋ has invariably shown preference for the tetrahedral sites, and Ni2＋ has the preference for the octahedral sites. The occupancy of Fe3＋ linearly increases on the tetrahedral sites, and sharply decreases on the octahedral sites with increasing x, owing to its gradual replacement by Ni2＋ on the octahedral sites. It indicates that due to the occupation of octahedral sites by the majority of Ni2＋, Fe3＋ decreasingly migrated from the octahedral sites to the tetrahedral sites and substituted Co3＋ sites, which made the number of Co3＋ in the tetrahedral sites decreasing. According to the measurement results of XRD and the infrared radiant tester analysis, the lattice parameter and infrared radiance have shown a nonlinear variation, exhibiting the infrared average radiance of 0.92 in the 8-14μm waveband, and the results demonstrate that these Co-Zn-Ni spinel ferrites have potential for application in a wide range of infrared heating and drying materials.
基金supported by the grants PBZ-MEiN/01/2006/09 (M. Hasiak)PBZ-KBN-115/T08/04 (J. Kaleta)
文摘The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 alloy, inhomogeneous in the as-quenched state, crystallized after annealing at 948 K for 0.5 h and consisted of Nd2Fe14B-type, Fe2B and paramagnetic phases. The rapidly solidified Fe64Co5Nd6Y6B19 alloy contained the Nd2Fel4B-type and paramagnetic phases. The annealing of the bulk Fe67CosNd3Y6B19 alloy at 948 K for 0.5 h led to hard magnetic properties. However, the bulk Fe64Co5Nd6Y6B19 alloy exhibited good hard magnetic properties directly after preparation.
基金Project supported by the Second Stage of Brain Korea 21 ProjectProject(RTI04-01-03) supported by the Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscopy measurements at room temperature. From the analysis of the Moessbauer spectra, it is observed that s-electron density, electric field gradient （EFG）, quadrupole coupling constant （QCC） and the net hyperfine magnetic fields acting on the Moessbauer nuclei-FeA^3＋ and FeB^3＋ change with the increase of Ti^4＋ doping in Mg0.95Mn0.05Fe2O4. The hyperfine magnetic field decreases with the increase of Ti^4＋ doping.
基金Project supported by the Second Stage of Brain Korea 21 ProjectProject(RTI04-01-03) supported by the Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.
基金Project supported by the National Natural Science Foundation of China (40572029)
文摘The ideal formula for chevkinite can be expressed as A4BC2D2Si4O22. It is important to determine the valence state and site occupation proportions for Fe among the B, C, and D octahedral sites as it may help to identify different species in the chevkinite group. Non-metamict chevkinite-（Ce） from Mianxi alkali feldspar-granite, Sichuan Province, China, was investigated using Moessbauer spectroscopy. The Fe^3＋/∑Fe ratio was 39.2%. A significant increase of Fe^3＋ occured during metamictization and annealing for chevkinite-group minerals. In metamict samples Fe tended to lower coordination, According to the correlation between bond length and isomer shift （IS）, the quadrupole doublets with IS = 1.10 and 0.94 mm·s^-1 can be assigned to Fe^2＋ in the B and C octahedral sites, respectively. Based on the correlation between octahedral distortion and quadrupole splitting （QS）, the quadrupole doublets with QS = 0.86 and 0.77 mm·s^-1 can be assigned to Fe^3＋ in the C and D sites, respectively. The simplified formula can be revised as： Ce4Fe^2＋ （Ti, Fe^2＋, Fe^3＋ ）2（Ti, Fe^3＋ ）2Si4（O,OH）22. It indicated that the non-metamict chevkinite-（Ce） belonged to Fe^2＋ end member of the chevkinite group because Fe^2＋ was the predominant component in the B site.
