M. BOUSSENDEL Abdelmadjid

The present study investigates the adsorption-induced resonance frequency shift of a biomolecule-resonator system, considering the shear distortion effect, distributed adatoms, and small-scale effects using nonlocal elasticity theory. The adsorption-induced energy is modeled using a distributional approach for both the bio-receptor and spike protein. The dynamic behavior model for a microbeam resonator is derived, incorporating surface stress. The functional microbeam approach and the localized biomolecule approach are employed, along with van der Waals (vdW) interactions using the Lennard-Jones (6–12) potential to calculate the influence of all applied conditions. Explicit inertia moment and shear force are determined based on the nonlocal Timoshenko beam equations, with residual stress applied as an additive axial load. Numerical results demonstrate that the computed frequency shift depends on the active surface parameters, adsorbed adatoms, as well as the localized receptor and spike. The evaluation of results indicates that interatomic phenomena make the microsystem softer, emphasizing the importance of considering it in computations. Thus, the derived model is suitable for investigating the dynamic behavior of the biomolecule-resonator, applicable for determining both mass and density of spike and virus in the presence of adatom bonds.

Lanthanum manganite (LaMnO3) is a complex oxide compound with various applications in wide
fields, including solid oxide fuel cells, magnetic and electronic devices, catalysts, and multiferroics.
Several available methods were used by researchers to prepare LaMnO3 such as solid-state synthesis,
sol-gel method, hydrothermal synthesis, co-precipitation method, and microwave-assisted synthesis,
choosing a method depends on several factors, like desired particle size, morphology, purity, crystal
structure of the LaMnO3, and the availability of resources and equipment.
This study investigated the kinetics of LaMnO3 doped with magnesium ceramics synthesized using
sol-gel method and starting materials as lanthanum nitrate (La (NO3)3*6H2O), manganese nitrate
(Mn(NO3)2*6H2 O), Magnesium nitrate (Mg(NO3)2*6H2O), and citric acid monohydrate
(C6H8O7*H2O). In order to characterize the results, various techniques were used, including
thermogravimetry (TG), differential thermal analysis (DTA), and X-ray powder diffraction (XRD). The
activation energy (Ea) of La0.7Mg0.3MnO3 phase formation was measured by heat treating the sample
up to 600 °C in various rates (0.3, 0.5, 0.7, and 1 °C/min) using differential thermal analysis (DTA).
Using Kissinger, Boswell, and Ozawa methods ERaR values were calculated and found to be 184, 189,
and 185 kJ/mol, respectively.
Both the growth morphology parameter n and the dimension of crystal growth m were determined to
be approximately 1.5, suggesting that bulk nucleation with a constant number of nuclei was the
dominant mechanism in La0.7Mg0.3MnO3 crystallization, which was followed by one-dimensional
growth controlled by interface reaction. The tracking of the phase Transformations done by DTA at
different temperatures (260, 400, 700, and 1100 °C) were analyzed using X-ray diffraction.
Additionally, we analyzed the material's structural properties at different sintering temperatures (700,
800, 900, 1000, and 1100 °C) for 4 hours. Finally, we examined the changes in the crystal dimension
of the material in consideration of both temperature and time.
Keywords: Phase Transformations, activation energy, Sintering, crystallization kinetics

This study focused on the synthesizing, phase transformation, and sintering behavior of
Lanthanum manganite (LaMnO3), and the importance of such material due to its imbedded
potential applications in various fields, including catalysis, energy storage, and solid oxide
fuel cells. The sol-gel auto-combustion method was used in the preparation of the LaMnO3
sample, Sol-Gel method is known to it superior qualities such as high purity, homogeneous
materials, and the ability to control particle size and morphology. The investigation of
LaMnO3 sample phase transformation and sintering behavior was done in this study using
several analytical techniques, thermogravimetry (TG), differential thermal analysis (DTA),
and X-ray diffraction (DRX) analysis. In order to describe the energy barrier required for a
particular process to occur such as a phase transformation or a chemical reaction, the
activation energy (EA) for the phase transformation was calculated using three different
methods: The Kissinger, Boswell, and Ozawa method. EA value was determined to be 173.8,
184, and 170 kJ/mol, respectively. which provides important information about the energy
requirements for the phase transformation to occur for LaMnO3 materials, this information
is extremely useful in the conditions of the process throughout designing and optimizing. The
parameters that describe the reaction mechanism and the rate of the process are called kinetic
parameters of Avrami n and m, which were calculated and found to be approximately 1.5.
Overall, this study is essential because it provides insightful scope into the phase
transformation and sintering behavior of LaMnO3.
Keywords:
 Corresponding Author Email : zaamdj@gmail.com; abdelmadjid-boussendel@univ-msila.dz;
foudil.sahnoune@univ-msila.dz

We have study in this work the substrate effect of the Rhodium (Rh) on the magnetic
properties of the Fe(001) monolayer in the Fe(001)/Rh system by the generalized gradient
approximation (GGA), within the Full potential linearized augmented plane waves method
(FPLAPW) based on density functional theory (DFT). The calculations showed that the
values of the spin and orbital magnetic moments are proportional to the lattice parameter a,
and the values of the orbital magnetic moment are very small compared to those of the spin
magnetic moment, which implies that the magnetism becomes from the spin in the transition
metals, moreover we also note that there is a large increase in the value of the magnetic
moment of the monolayer Fe(001) compared to the value of the bulk. From the figures of the
density of state, we showed that the magnetism is due to the d layer and that the contribution
of the s, p and f layers to the total magnetic moment is negligible. Also, the calculations
showed that the magnetic moments are not related to the number of k points in the Irreducible
Brillouin zone.
Keywords: DFT, FLAPW, Magnetic Properties, spin magnetic moment, orbital magnetic
moment

Kinetics, Phase Transformations and Sintering of Mg-doped LaMnO3
Foudil SAHNOUNE1, Amar DJEMLI1, Abdelmadjid BOUSSENDEL1, Essebti Dhahri2, and Nouari Saheb3
1physics and materials chemistry laboratory, Department of Physics, University of M’sila, 28000 M’sila, Algeria
23Laboratoire de Physique Appliquée, Faculté des Sciences, Université de Sfax, B.P.1171, 3000 Sfax, Tunisia
3Dep. of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
Abstract
Lanthanum manganite (LaMnO3) is a complex oxide compound with various applications in wide fields, including solid oxide fuel cells, magnetic and electronic devices, catalysts, and multiferroics. Several available methods were used by researchers to prepare LaMnO3 such as solid-state synthesis, sol-gel method, hydrothermal synthesis, co-precipitation method, and assisted microwave synthesis, choosing a method depends on several factors, like desired particle size, morphology, purity, crystal structure of the LaMnO3, and the availability of resources and equipment.
This study investigated the kinetics of LaMnO3 doped with magnesium ceramics synthesized using sol-gel method and starting materials as lanthanum nitrate (La (NO3)3*6H2O), manganese nitrate (Mn(NO3)2*6H2O), Magnesium nitrate (Mg(NO3)2*6H2O), and citric acid monohydrate (C6H8O7*H2O). In order to characterize the results, various techniques were used, including thermogravimetry (TG), differential thermal analysis (DTA), and X-ray powder diffraction (XRD). The activation energy (Ea) of La0.7Mg0.3MnO3 phase formation was measured by heat treating the sample up to 600 °C in various rates (0.3, 0.5, 0.7, and 1 °C/min) using differential thermal analysis (DTA). Using Kissinger, Boswell, and Ozawa methods Ea values were calculated and found to be 184, 189, and 185 kJ/mol, respectively.
Both the growth morphology parameter n and the dimension of crystal growth m were determined to be approximately 1.5, suggesting that bulk nucleation with a constant number of nuclei was the dominant mechanism in La0.7Mg0.3MnO3 crystallization, which was followed by one-dimensional growth controlled by interface reaction. The tracking of the phase Transformations done by DTA at different temperatures (260, 400, 700, and 1100 °C) were analyzed using X-ray diffraction. Additionally, we analyzed the material's structural properties at different sintering temperatures (700, 800, 900, 1000, and 1100 °C) for 4 hours. Finally, we examined the changes in the crystal dimension of the material in consideration of both temperature and time.
Keywords: Phase Transformations, activation energy, Sintering, crystallization kinetics
 Corresponding Author Email: foudil.sahnoune@univ-msila.dz

Lanthanum Manganite LaMnO3 Crystallization Kinetics Prepared Through Sol-Gel Auto-Combustion Method

Abdelmadjid BOUSSENDEL1, Amar DJEMLI1, Foudil SAHNOUNE1, 2

1physics and materials chemistry laboratory, Department of Physics, University of M’sila, 28000 M’sila, Algeria
2Research Unit on Emerging Materials (RUEM), Ferhat Abbas of Setif 01, Setif 19000, Algeria


Abstract

This study focused on the synthesizing, phase transformation, and sintering behavior of Lanthanum manganite (LaMnO3), and the importance of such material due to its imbedded potential applications in various fields, including catalysis, energy storage, and solid oxide fuel cells. The sol-gel auto-combustion method was used in the preparation of the LaMnO3 sample, Sol-Gel method is known to it superior qualities such as high purity, homogeneous materials, and the ability to control particle size and morphology. The investigation of LaMnO3 sample phase transformation and sintering behavior was done in this study using several analytical techniques, thermogravimetry (TG), differential thermal analysis (DTA), and X-ray diffraction (DRX) analysis. In order to describe the energy barrier required for a particular process to occur such as a phase transformation or a chemical reaction, the activation energy (EA) for the phase transformation was calculated using three different methods: The Kissinger, Boswell, and Ozawa method. EA value was determined to be 173.8, 184, and 170 kJ/mol, respectively. which provides important information about the energy requirements for the phase transformation to occur for LaMnO3 materials, this information is extremely useful in the conditions of the process throughout designing and optimizing. The parameters that describe the reaction mechanism and the rate of the process are called kinetic parameters of Avrami n and m, which were calculated and found to be approximately 1.5. Overall, this study is essential because it provides insightful scope into the phase transformation and sintering behavior of LaMnO3.

Keywords: differential thermal analysis, Phase Transformations, activation energy, crystallization kinetics


 Corresponding Author Email: abdelmadjid.boussendel@univ-msila.dz

The all-electron full-potential linearized augmented plane-wave method is used to show that the variation of tetragonality of the L1 0 MnPt antiferromagnet switches the magnetization from an easy axis to an easy plane. The optimum lattice parameters are obtained and the changing from inplane to out-of plane is explained by a competition between the strong spin orbit coupling and weak magnetization of Pt with the large magnetization and weak spin–orbit coupling of Mn. Finally we present the X-ray magnetic linear dichroism used to investigate the magnetic anisotropy of the antiferromagnet MnPt.

The electronic structure and magnetic properties of ferromagnetic thin films of iron have been the subject in recent years of many theoretical and experimental research groups because of their various physical properties of interest in technological applications. For example, the storage of information, magnetic heads and magnetic recording.

Mullite porous ceramics were prepared by an in situ reaction join technique using a Kaolinite,
aluminum oxide, and silicon carbide as raw materials. The raw materials were mixed in different ratios. From homogeneous mixture, standard samples were prepared via uniaxial compaction. The Kaolinite was a reaction sintered with Alumina and SiC, a in the temperature range 1200–1600 °C for
2 h. Dilatometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM) complementary techniques were used to characterize the prepared materials. The effect of SiC content on the microstructure, densification, and hardness of the samples was investigated. All prepared samples showed the same phase transitions that ended at 1500 ° C with the formation of mullite in kaolinitealumina mixture and kaolinite-alumina -SiC mixture. The kaolinite experiences transformation into mullite and excess silica, the mullite and the silica phases contents increased with increased sintering temperature. It is also commonly observed that the SiC content reduces the density gradually while increasing the sintering temperature . The sintering percentage of samples sintered decreased with an increase in SiC content. The pores in the mullite ceramics were formed by accumulating particles of SiC. The surface of SiC was oxidized to SiO2 at high temperature. With further increasing the temperature, SiO2 reacted with Al2O3 to form mullite. SiC particles were bonded by the oxidationderived SiO2 and mullite. The results show that when 2 wt % SiC and 14% SiC were added, the open porosity of the porous mullite were 3.1 % and 16.8 %, respectively. The Vicker’s microhardness of mullite was measured under an applied indentation load of 500 g, showed values of hardness decreased with an increase in SiC content.

The studies of the magnetic anisotropy of Co ultrathinfilms have recently attracted much interest experimentally as well as theoretically. One reason for the interest is that the properties of perpendicular magnetic anisotropy may apply to magnetic high-density recording and magnetic thin-film sensors [1]. The aim of this work is to study the strain effects on the magnetic properties and magnetic anisotropy of a Co monolayer

The studies of the magnetic anisotropy of ferromagnetic FeCo ultrathinfilm have recently attracted much interest experimentally as well as theoretically. One reason for the interest is that the properties of perpendicular magnetic anisotropy may apply to magnetic high-density recording and magnetic thin-film sensors [1]. The aim of this work is to study the strain effects on the magnetic properties of the FeCo monolayer.

The electronic structure, magnetic properties, and magnetic anisotropy energy (MAE) of the insulating antiferromagnetic bulk CoO and CoO strained by silver or MnO substrates have been studied by means of three different methods: (1) a simple model based on the crystal-field approach, (2) the full-potential linear augmented plane-waves method within the generalized gradient approximation (GGA), and (3) the so-called GGA+U method. In all methods the spin-orbit coupling is included. In the third method, the Hubbard interaction U is used to treat the strong electron-electron interaction due to the cobalt localized open d shell. The results of the various calculations for bulk CoO and those of CoO strained by silver or MnO substrates are discussed and compared with available experimental data and other calculations. The GGA predicts incorrectly that bulk CoO is a metallic oxide and its spin magnetic moment is oriented along the inclination angle θ of 66° and the azimuth angle ϕ of 45° and the hard axis along the c direction. The orbital magnetic moment is also much smaller compared to experiment. On the contrary, within the GGA+U bulk CoO becomes an insulator as expected and the spin magnetic moment is oriented along the tetragonal c axis; it rotates in plane when CoO is strained by a silver substrate, and out of plane when strained by an MnO substrate. Within the GGA+U an unquenched orbital magnetic moment on the order of 1μB is obtained in both bulk CoO and CoO strained by MnO substrate but is much smaller (0.45μB) when CoO is strained by silver. All these results together with the values of MAE are in good agreement with experiment and our crystal-field analysis.

The magnetism of Cr layers on V(001) is determined by using a tight-binding Hubbard Hamiltonian in the unrestricted Hartree–Fock approximation. In all cases we obtain an antiferromagnetic (AF) coupling between Cr and nearest neighbors V with an important increase of the Cr magnetic moment at the interface as compared to its bulk value, and the magnetic moment on the V atoms decreases when the number of Cr layers increases. We find that the hybridization of the V and Cr d-bands plays an important role in determining the magnetism of the Cr/V(001) system.

Abstract

We have investigated the magnetic properties of Cr layers adsorbed on W(001) by means of self-consistent tight-binding calculations in the framework of the Hubbard Hamiltonian within the unrestricted Hartree - Fock approximation. We have observed that the polarization appears at the Cr - W interface until the fourth plane is reached and the magnetic moment in the W interface decreases when the number of Cr layers increases. In all cases we obtain an antiferromagnetic coupling between Cr layers and Cr - W interfaces. The general results can be understood in terms of the competition between surface and interface effects.