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Critical parameters near the phase transition temperature in La_(0.67–x)Dy_xPb_(0.33)MnO_3

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Journal of Rare earths 2015年第2期33卷 168-176页

作者： N.Zaidi S.Mnefgui A.Dhahri e.k.hlil J.Dhahri Laboratory of Condensed Matter and Nanosciences University of Monastir5019 Tunisia Institut Néel CNRS and Joseph Fourier universityB.P.16638042 Grenoble France

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.

关键词： Arrott plots critical exponent site A-substitution rare earths

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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Journal of Rare earths 2015年第3期33卷 263-270页

作者： Mounira Abassi N.Dhahri J.Dhahri k.Taibi e.k.hlil Laboratory of Condensed Matter and Nanosciences University of Monastir 5019 Tunisia Institut Néel CNRS and Joseph Fourier university B.P.166 38042 Grenoble France Institut Néel CNRS et Université Joseph Fourier BP 166 F-38042 Grenoble cedex 9 France

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.

关键词： perovskite manganites phase transition entropy critical properties rare earths

Study of electronic and magnetic properties of MnS layers

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Chinese Physics B 2012年第12期21卷 408-411页

作者： R.Masrour e.k.hlil M.Hamedoun A.Benyoussef O.Mounkachi Laboratory of Materials ProcessesEnvironment and QualityCady Ayyed UniversityNational School of Applied SciencesSafiMorocco LMPHe(URAC 12) Faculty of ScienceMohammed V-Agdal UniversityRabatMorocco Institut Neel CNRS et Universite Joseph FourierBP 166F-38042 Grenoble Cedex 9France Institute of Nanomaterials and Nanotechnologies MAScIRRabatMorocco HassanⅡAcademy of Science and Technology RabatMorocco

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 N@el temperature, and the critical exponent associated with the magnetic susceptibility are obtained for the MnS layer.

关键词： MnS layers electronic and magnetic structure magnetic moment N^el temperature,exchange interactions

Magnetic and specific heat studies of the frustrated er_2Mn_2O_7 compound

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Journal of Rare earths 2013年第1期31卷 54-59页

作者： N.Ben Amor M.Bejar e.Dhahri M.A.Valente P.Lachkar e.k.hlil Laboratory of Applied Physics Faculty of Sciences of SfaxBP 1171University of Sfax I3N and Physics Department University of Aveiro MCMF Néel InstitutCNRS25 avenue des MartyrsBuilding FBP 16638042 Grenoble cedex 9France MCBT Institut NéelCNRS25 avenue des MartyrsBuilding EBP 16638042 Grenoble cedex 9France

A new erzMn207 compound was synthesized by the ceramic method and its crystal structure was characterized LJsing powder X-ray diffraction （XRD） and observed by scanning electron microscopy （SeM）. The magnetic properties were investigated using a BS2 magnetometer and the heat capacity was studied using a quantum design （PPMS）. The structural study revealed that this compound was monophasic and crystallized in the monoclinic system with the P2/M space group. Magnetization measurements were carried out in the temperature range of 1.8-200 k under an applied magnetic field of 0.05 T. A crossover from a room temperature para- magnetic phase to an antiferromagnetic one at low temperature was detected from the magnetic study. The magnetic susceptibility, in the paramagnetic region above 40 k, was found to present a simple Curie-Weiss type behavior. From the specific heat （G,） measurements in magnetic fields up to 5 T, we noted the presence of a wide peak characteristic of a second order magneto-structural transition.

关键词： magnetic frustration magnetic phase transition specific heat rare earths

Hydrogen storage of Mgi-xMxH2 （M--Ti, V, studied using first-principles calculations re）

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Chinese Physics B 2012年第9期21卷 477-483页

作者： M.Bhihi M.Lakhal H.Labrim A. Benyoussefa A.eI kenz O.Mounkachi e.k.hlil Laboratoire de Magnetisme et de Physique des Hautes energies associe au CNRST (URAC 12) Departement de PhysiqueB.P. 1014 Faculte des Sciences Universite Mohammed V-Agdal Rabat Morocco National Centre for energy Sciences and Nuclear Techniques ONESTEN Morocco Institute of Nanomaterials and Nanotechnologies MACslR Rabat Morocco Hassan II Academy of Science and Technology Rabat Morocco Institut N6el CNRS-UJF 38042 Grenoble Cedex 9 France

In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mgl-xMxH2 （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.

关键词： first-principles calculation formation energy electronic structure hydrogen storage

electronic and magnetic structures of V-doped zinc blende Zn_(1-x)V_xN_yO_(1-y) and Zn_(1-x)V_xP_yO_(1-y)

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Chinese Physics B 2011年第8期20卷 419-424页

作者： N.Mamouni M.Belaiche A.Benyoussef A.el kenz H.ez-Zahraouy M.Loulidi e.H.Saidi e.k.hlil Laboratoire de Magntisme et de Physique des Hautes energies Dpartement de Physique Associ au CNRSTURACB.P.1014Facult des SciencesRabatMorocco Laboratoire de Magntisme Matriaux MagntiquesMicro-ondes et CramiqueENSRabatMorocco INANOTeCH Institute of Nanomaterials and NanotechnologyMAScIRRabatMorocco Laboratoire de Physique des Hautes energies Dpartement de Physique B.P.1014Facult des SciencesRabatMorocco Institut Nel MCMF-UJFC.N.R.SB.P.16638042 Grenoble CedexFrance

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.

关键词： ab initio calculations density of states magnetic moment doping diluted magneticsemiconductors

Spin and Orbital Magnetisms of NiFe Compound:Density Functional Theory Study and Monte Carlo Simulation

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Chinese Physics Letters 2018年第3期35卷 58-61页

作者： R.Masrour A.Jabar e.k.hlil M.Hamedoun A.Benyoussef A.Hourmatallah k.Bouslykhane A.Rezzouk N.Benzakour Laboratory of Materials ProcessesEnvironment and QualityCady Ayyed UniversityNational School of Applied SciencesSail 63 46000Morocco Institut Neel CNRS et Universite Grenoble AlpesBP 166F-38042 Grenoble Cedex 9France Institute of Nanomaterials and Nanotechnologies MAScIRRabatMorocco Hassan II Academy of Science and Technology RabatMorocco equipe de Physique du Solide Laboratoire LIPIEcole Normale SuperieureBP 5206BensoudaFesMorocco Laboratoire de Physique du Solide Universite Sidi Mohammed Ben AbdellahFaculte des Sciences Dhar MahrazBP 1796FesMorocco

The self-consistent ab initio calculations based on the density functional theory approach using the full potential linear augmented plane wave method are performed to investigate both the electronic and magnetic properties of the NiFe compound. Polarized spin within the framework of the ferromagnetic state between magnetic ions is considered. Also, magnetic moments considered to lie along （001） axes are computed. The Monte Carlo simulation is used to study the magnetic properties of NiFe. The transition temperature To, hysteresis loop, coercive field and remanent magnetization of the NiFe compound are obtained using the Monte Carlo simulation.

关键词： Fe Spin and Orbital Magnetisms of Ni Fe Compound Ni

exploration of chromene-based BioAIegens

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National Science Review 2024年第3期11卷 47-48页

作者： Fritz e.kühn Department of Chemistry&Catalysis Research Center School of Natural Sciences Technical University of Munich

Photoemission efficiency is usually higher in solution than in solid *** compounds however, display a reverse behavior. Such a behavior is called aggregation-induced emission(AIe).

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emission colour tuning in kLnF_(4):Yb^(3+),er^(3+)/Ho^(3+)phosphor

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Journal of Rare earths 2024年第1期42卷 57-65,I0002页

作者： Janani k Gayathri e Vijayatha V Ramasubramanian S Thiyagarajan P Department of Science and Humanities Nehru Institute of TechnologyKaliapuramThirumalayampalayamCoimbatoreIndia Department of Sciences Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatoreIndia Department of Physics Anna UniversityChennaiIndia

kLnF_(4):Yb^(3+),er^(3+)/Ho^(3+)(Ln=Y,Yb,Gd)phosphors were prepared by solid-state reaction *** each of the Yb^(3+)/er^(3+)and Yb^(3+)/Ho^(3+)co-doped phosphors independently,phase confirmation and morphological examination were accomplished using the X-ray diffraction technique and scanning electron microscope analysis.X-ray photoelectron spectroscopy analysis shows the charge state and existence of lanthanides and *** luminescence emissions of green and red colour were detected for the synthesized *** changes in the upconverted emission intensities and colour output pertaining to the change of the lanthanide host matrix along with dopants were investigated for the prepared *** the upconversion luminescence,erbium-doped samples exhibit a predominance of red emission while holmium-doped samples display a prevalence of green *** rare-earth er/Ho doped kYbF4shows strong red emission compared to other ***_(4):Yb,er/Ho exhibits relatively significant green upconve rsion emissions,while Yb,er-doped kGdF_(4)host displays a 10-fold increase in green/red emission ratio with an increase in the input power of 20-780 *** photoluminescence studies and decay curve analysis were carried out using UV light excitation for the developed phosphors.A higher lifetime of 2.2 ms was measured for the downshifting red emission in the Ho doped kYbF_(4)*** study suggests a potential for colour tunability in the upconversion and downshifting emissions through host modifications to the fluoride phosphor.

关键词： Rare earths energy transfer upconversion Downshifting Colour coordinates