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Critical parameters near the ferromagnetic-paramagnetic phase transition in La_(0.67–x)Y_xBa_(0.23)Ca_(0.1)MnO_3 compounds(x=0.10 and x=0.15)
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作者 Mounira Abassi N.Dhahri +2 位作者 J.Dhahri K.Taibi E.K.Hlil 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2015年第3期263-270,共8页
The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic(PM)-ferromagnetic(FM) phase transition were investigated through various techniques. These i... The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic(PM)-ferromagnetic(FM) phase transition were investigated through various techniques. These involved modified Arrott plots, Kouvel-Fisher method and Widom scaling relation. Magnetic data, analyzed in the critical region, using the above methods, yielded the critical exponents for(x=0.10) La0.57Y0.10Ba0.23Ca0.1Mn O3(β=0.312±0.002 and γ=1.147±0.003 at T C=299.23±0.05 K). Moreover, the estimated critical exponents of(x=0.15) La0.52Y0.15Ba0.23Ca0.1Mn O3 were β=0.286±0.004 and γ=0.943±0.002 at T C=289.53±0.06 K. The critical exponents’ values were close to the theoretical values of 3D-Ising model and tricritical mean-field model. These results suggested that the present composition should be close to a tricritical point in the La0.67–x Y x Ba0.23Ca0.1Mn O3 phase diagram. Expressing the field dependence as ΔS M∝H n allowed us to establish a relationship between the exponent n and the critical exponents of the material and to propose a phenomenological universal curve for the field dependence of ΔS M. 展开更多
关键词 临界参数 化合物 临界指数 铁磁 相变 CA 比例关系 伊辛模型
Influence of bismuth on magnetism and magnetocaloric properties of LaFe11.6Si1.4 intermetallic compound
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作者 A. Boutahar K. Zehani +2 位作者 Bessais H. Lassri E.K. Hlil 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2015年第7期740-745,共6页
Crystal structure, magnetic properties and magnetocaloric effects(MCE) of La1–xBixFe11.4Si1.6(x=0.0 and 0.1) compounds were investigated by X-ray diffraction and magnetization measurements. The La1–xBixFe11.4Si1.6 c... Crystal structure, magnetic properties and magnetocaloric effects(MCE) of La1–xBixFe11.4Si1.6(x=0.0 and 0.1) compounds were investigated by X-ray diffraction and magnetization measurements. The La1–xBixFe11.4Si1.6 compounds presented a cubic Na Zn13 type structure. First, the magnetization behavior and the magnetic transition were analyzed in terms of Landau theory. Then, Bi substitution for La in La1–xBixFe11.4Si1.6 compounds led to a decrease in magnetic entropy change(-ΔSmaxM) but an increase in Curie temperature(TC) significantly. The significant increase of TC by Bi substitution from 202.5 to 256 K for x=0.0 and x=0.1 respectively was attributed to an increase in the Fe-Fe exchange interactions. Moreover, magnetocaloric effect was calculated in terms of isothermal magnetic entropy change. The maximum values of(-ΔSmaxM) of La1–xBixFe11.4Si1.6 for x=0.0 and 0.1 compounds were found to be, respectively, 22.56 and 4.36 J/(kg·K) under an applied magnetic field change of 5 T. For the same applied magnetic field(μ0H=5 T), the relative cooling power(RCP) values were found to vary between 487 and 296 J/kg. 展开更多
关键词 金属间化合物 性能影响 磁性 Landau理论 等温磁熵变 交换相互作用 晶体结构 磁热效应
Critical parameters near the phase transition temperature in La0.67-xDyxPb0.33MnO3
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作者 N. Zaidi S. Mnefgui +2 位作者 A. Dhahri E.K. Hlil J. Dhahri 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2015年第2期168-176,共9页
La0.67–xDyxPb0.33MnO3(x=0.00 and x=0.10) were elaborated by the solid state method and checked by X-ray diffraction. Close to magnetic temperature transition, the order transition and the critical behavior were inves... La0.67–xDyxPb0.33MnO3(x=0.00 and x=0.10) were elaborated by the solid state method and checked by X-ray diffraction. Close to magnetic temperature transition, the order transition and the critical behavior were investigated by dc magnetization measurements versus x composition. The critical properties were investigated through various techniques such as modified Arrott plot(MAP), Kouvel-Fisher(KF) method and critical isotherm(CI) analysis based on the data of static magnetic measurements recorded around the Curie temperature TC. The values of critical exponents(β and γ) estimated were found to lie between those predicted for a 3D-Ising model for x=0.00 and those of 3D-Heisenberg model for x=0.10. The reliability of the critical exponent's values was confirmed by the Widom scaling relation and the universal scaling hypothesis. The change in the universality class should be due to the increase of the Dy content. 展开更多
关键词 相转变温度 关键参数 临界行为 临界指数 X射线衍射 海森堡模型 直流磁化 临界性质
Study of electronic and magnetic properties of MnS layers
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作者 R. Masrour E. K. Hlil +2 位作者 M. Hamedoun A. Benyoussef O. Mounkachi 《中国物理B:英文版》 SCIE EI CAS CSCD 2012年第12期408-411,共4页
<正>Self-consistent ab initio calculations,based on the density functional theory(DFT) and using the full potential linear augmented plane wave(FLAPW) method,are performed to investigate both electronic and magn... <正>Self-consistent ab initio calculations,based on the density functional theory(DFT) and using the full potential linear augmented plane wave(FLAPW) method,are performed to investigate both electronic and magnetic properties of the MnS layers.Polarized spin and spin-orbit coupling are included in the calculations within the framework of the antiferromagnetic state between two adjacent Mn layers.Magnetic moments considered to lie along axes are computed. Obtained data from ab initio calculations are used as input data for the high temperature series expansion(HTSE) calculations to compute other magnetic parameters.The zero-field high temperature static susceptibility series of the spin-4.39 nearest-neighbour Heisenberg model on centred face cubic(FCC) and lattices is thoroughly analysed by a power series coherent anomaly method(CAM).The exchange interactions between the magnetic atoms,the Neel temperature,and the critical exponent associated with the magnetic susceptibility are obtained for the MnS layer. 展开更多
关键词 反铁磁性 MNS HEISENBERG模型 性能 电子 全势线性缀加平面波 自旋轨道耦合 从头计算
Hydrogen storage of Mgi-xMxH2 (M--Ti, V, studied using first-principles calculations re)
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作者 M. Bhihi M. Lakhal +4 位作者 H. Labrim A. Benyoussefa A. EI KEnz O. Mounkachi E. K. Hlil 《中国物理B:英文版》 SCIE EI CAS CSCD 2012年第9期477-483,共7页
In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mg 1 x M x H 2 (M=Ti, V, Fe, 0 ≤ x ≤ 0.1), are studied using the Korringa-Kohn-Rostoker (KKR) calculation with the coherent potential app... In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mg 1 x M x H 2 (M=Ti, V, Fe, 0 ≤ x ≤ 0.1), are studied using the Korringa-Kohn-Rostoker (KKR) calculation with the coherent potential approximation (CPA) . In particular, the nature and concentrations of the alloying elements and their effects are studied. Moreover, the material’s stability and hydrogen storage thermodynamic properties are discussed. In particular, we find that the stability and the temperature of desorption decrease without significantly affecting the storage capacities. 展开更多
关键词 第一原理计算 储氢性能 热力学性质 相干势近似 合金元素 存储容量 稳定性
Electronic and magnetic structures of V-doped zinc blende Zn1-xVxNyO1-y and Zn1-xVxPyO1-y
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作者 N. Mamouni M. Belaiche +5 位作者 A. Benyoussef A. E1 KEnz H. Ez-Zahraouy M. Loulidi E. H. Saidi E. K. Hlil 《中国物理B:英文版》 SCIE EI CAS CSCD 2011年第8期419-424,共6页
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 approxim... 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. 展开更多
关键词 磁性结构 杂质掺杂 闪锌矿 电子 V型 相干势近似 第一原理 能带结构
Hydrogen storage of Mg_(1-x)M_x H_2 (M=Ti, V, Fe) studied using first-principles calculations
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作者 M. Bhihi M. Lakhal +4 位作者 H. Labrim A. Benyoussef A. El KEnz O. Mounkachi E. K. Hlil 《Chinese physics B》 CSCD 2012年第9期477-483,
In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mg 1 x M x H 2 (M=Ti, V, Fe, 0 ≤ x ≤ 0.1), are studied using the Korringa-Kohn-Rostoker (KKR) calculation with the coherent potential ap... In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mg 1 x M x H 2 (M=Ti, V, Fe, 0 ≤ x ≤ 0.1), are studied using the Korringa-Kohn-Rostoker (KKR) calculation with the coherent potential approximation (CPA) . In particular, the nature and concentrations of the alloying elements and their effects are studied. Moreover, the material’s stability and hydrogen storage thermodynamic properties are discussed. In particular, we find that the stability and the temperature of desorption decrease without significantly affecting the storage capacities. 展开更多
关键词 FIRST-PRINCIPLES calculation formation energy electronic structure hydrogen storage
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