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1.
M. Belaiche J. Aride T. Biaz A. Moqine A. Boukhari M. Drillon 《Phase Transitions》2013,86(1-4):149-155
In the last two decades, many studies have been reported on infinite Id networks of magnetically interacting metal ions. Until now, closed-form expressions for the partition function and related properties were mainly derived for the S = f Ising chain model (Ising, 1925), the XY model (Kastura, 1962) or for the classical limit S –t co with arbitrary spin dimensionality (Fischer, 1964). Recently, experimental and theoretical studies have focused on new Id systems made of alternating spin and/or Lande factors (Georges, Curely and Drillon, 1985; Drillon et al., 1983). This has motivated our interest in the behavior of new systems of copper(II) ions in which the magnetic sites form an exotic stacking in one direction of the crystal. Then, the specific behavior is related to the competition between different interactions, as occurs in the systems reported here, namely A3Cu3(PO4)4, with A = Ca, Sr, Cu3(PO4)2 and Cu2O(SO4). 相似文献
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N. Mamouni M. Belaiche A. Benyoussef A. El Kenz H. Ez-Zahraouy M. Loulidi E. H. Saidi E. K. Hlil 《中国物理 B》2011,20(8):87504-087504
Electronic and magnetic structures of zinc blende ZnO doped with V impurities are studied by first-principles calculations based on the Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA).Calculations for the substitution of O by N or P are performed and the magnetic moment is found to be sensitive to the N or P content.Furthermore,the system exhibits a half-metallic band structure accompanied by the broadening of vanadium bands.The mechanism responsible for ferromagnetism is also discussed and the stability of the ferromagnetic state compared with that of the paramagnetic state is systematically investigated by calculating the total energy difference between them by using supercell method. 相似文献
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A. Fakhim Lamrani M. Belaiche A. Benyoussef A. El Kenz 《Journal of magnetism and magnetic materials》2010,322(4):454-458
The electronic structure and ferromagnetic properties of rutile TiO2 doped with double-impurities Ti1−2xCrxMnxO2 has been investigated using first-principles calculations within the density-functional theory (DFT) and the local density approximation (LDA), functional for treating the effects of exchange and correlation. They were performed using the scalar-relativistic implementation of the augmented spherical wave (ASW). The advantages of doping TiO2 with double impurities instead of single impurities are the increase of the total moment of the system and the exhibition of the half-metallic ferromagnetic nature in Cr- and Mn-doped TiO2 rutile. These behaviors are due to the hybridization of Cr 3d states and nearest-neighboring O 2p states. The spin-spin interaction between magnetic impurities examined by the total energy between parallel and antiparallel aligned states indicated that the Cr and Mn impurities are energetically favorable to be parallel coupled, which mean that the ferromagnetic state is more stable than the ferrimagnetic one. We proposed a bond magnetic polarons (BMP) model, based on localized carriers, to explain the mechanism of ferromagnetism in these systems. 相似文献
4.
O. Mounkachi M. Belaiche A. Benyoussef M. Sajieddine 《Solid State Communications》2011,151(13):938-942
Polycrystalline Zn0.6Cu0.4Fe2O4 ferrites have been prepared using a solid-state reaction technique. Their structural and magnetic properties have been studied, using X-ray diffraction and Mössbauer and magnetic measurements. These results have been compared to a more general theoretical study, on ZnxCu1−xFe2O4, based on mean field theory and high-temperature series expansions (HTSE), and extrapolated with the Padé approximant method. The nearest neighbour super-exchange interactions for the intra-site and the inter-site of ZnxCu1−xFe2O4 spinel ferrites, in the range 0≤x≤1, have been computed using the probability approach, based on Mössbauer data. The Curie temperature TC is calculated as a function of Zn concentration. The theoretical results obtained are in good agreement with the experimental results obtained by magnetic measurements. 相似文献
5.
Phase separation in both thin and thick films of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was studied by small-angle laser light scattering (SALLS), atomic force microscopy (AFM), optical microscopy, and X-ray photoelectron spectroscopy (XPS). Blend films with controlled thickness were obtained by spin-coating polymer-toluene solutions with various concentrations. Films with thicknesses smaller and larger than the maximum wavelength of concentration fluctuations were considered. Morphology of the blend films was characterized during and after phase separation. The obtained peculiar morphology was related to surface enrichment with the lower-surface-energy component, as was verified by XPS analyses. 相似文献
6.
Ahmani Ferdi Chouaib Belaiche Mohammed Iffer Elabadila 《Journal of Solid State Electrochemistry》2021,25(1):301-313
Journal of Solid State Electrochemistry - Monoclinic lithium vanadium phosphate Li3V2(PO4)3 is a very promising cathode candidate for applications in Li-ion batteries, with a high operational... 相似文献
7.
Dilute magnetic oxides are without doubt among the most interesting classes of magnetic materials. However, the nature of their electronic structure and magnetic exchange is far from understood. Here, we apply the ab initio augmented spherical wave (ASW) method, with corrected generalised gradient approximation to study the electronic structure and magnetic properties of doped TiO2 rutile with double impurities. The study reveals a half-metallic ferromagnetic behaviour for Ti1?2x Cr x Mo x O2, and the local magnetic moments of the impurities and their oxidation states agree with the charge transfer between Cr and Mo, which would lead to the ferromagnetic state through the double-exchange mechanism in transition metal oxides. 相似文献
8.
Conditions for unblocking reversible chemical modifications such as maleylation or citraconylation 'in situ' at the N-terminus of proteins after transfer of proteins to immobilon membranes from SDS-PAGE are described. Demaleylation or decitraconylation occurred at 55 degrees C in 70% formic acid (pH 1.50) during 60 min. During the unblocking reaction, Coomassie blue dye was completely removed, resulting in superior high performance liquid chromatographic separation of phenylthiohydantoin-amino acid (PTH-AA) after Edman degradation (automatic gas phase sequencer). The protein fixed on the matrix after demaleylation and removal of Coomassie blue was not degraded. The possible cleavage at the aspartyl-prolyl peptide bonds was considered, but no side reaction was observed. Furthermore, the incubation time in 70% formic acid at 55 degrees C could be reduced to 10 min in the absence of maleylation of the starting material, and this was suitable for the removal of Coomassie blue and the quantification of phenylthiolhydantoin-amino acids (PTH-AAs) by HPLC. The yield from the starting protein through SDS-PAGE, blotting, and Edman degradation to quantitative analysis of PTH-aminoacid(s) by HPLC was established. 相似文献
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10.
O. MounkachiM. Hamedoun M. Belaiche A. Benyoussef R. MasrourH. El Moussaoui M. Sajieddine 《Physica B: Condensed Matter》2012,407(1):27-32
Polycrystalline Mg0.6Cu0.4Fe2O4 ferrites have been prepared using solid-state reaction technique. Their structural and magnetic properties have been studied, using X-ray diffraction and magnetic measurements.Using mean field theory and high-temperature series expansions (HTSE), extrapolated with the padé approximants method, the magnetic properties of Mg1−xCuxFe2O4 have been studied. The nearest neighbor super-exchange interactions for intra-site and inter-site of the Mg1−xCuxFe2O4 ferrites spinels, in the range 0≤x≤1, have been computed using the probability approach, based on Mössbauer data. The Curie temperature Tc is calculated as a function of Mg concentration. The obtained theoretical results are in good agreement with experimental ones obtained by magnetic measurements. 相似文献