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71.
Bouhafs Khalfallah Fatima-Zohra Driss-Khodja Fatiha Saadaoui Mohammed Driss-Khodja Abdelkader Boudali Hanifi Bendaoud Bachir Bouhafs 《Journal of Computational Electronics》2018,17(4):1478-1491
The structural, elastic, electronic, vibrational, and optical properties of BaSe1?xTex alloys are investigated by means of the full-potential linearized augmented plane wave method. The exchange–correlation effects are treated with the local density approximation, as well as the GGA-PBE, GGA-PBEsol, and GGA?+?mBJ schemes of the generalized gradient approximation. Ternary BaSe1?xTex compounds have not yet been synthesized. Improved predictions of the structural parameters are obtained using the GGA-PBEsol approach. Calculations of the electronic and optical properties with the GGA?+?mBJ approach yield accurate results. Ternary BaSe1?xTex alloys are wide-band-gap semiconductors with a direct gap Γ–Γ. The upper valence band is mainly due to Se p and Te p states, while the bottom of the conduction band results essentially from Ba d states. The dielectric function, refractive index, reflectivity, absorption coefficient, and energy-loss function are calculated in the range 0–35 eV. The increase in x gives rise to a redshift of the optical spectra. BaSe1?xTex alloys exhibit reflective properties of metals in some energy ranges. The static dielectric constant ?1(0) and the static refractive index n0 are calculated. The investigation of the elastic and vibrational properties shows that ternary BaSe1?xTex should be mechanically and dynamically stable, elastically anisotropic, brittle, and relatively soft. 相似文献
72.
Slimane Haid Bouabdellah Bouadjemi Samir Bentata Tayeb Lantri Ali Çoruh Ali Zitouni Bachir Bouhafs Zoubir Aziz 《Journal of Superconductivity and Novel Magnetism》2018,31(12):3965-3979
The effects of spin polarization on the structure, magnetic, and optoelectronic properties of Cr-based series of double perovskites Sr2CrXO6 (X = La and Y) have been studied by using the full-potential linearized augmented plane-wave method (FP-LAPW), based on the density functional theory (DFT) as implemented in the Wien2k code, within the generalized gradient approximation (GGA), GGA + U, and GGA plus Trans-Blaha-modified Becke–Johnson (TB-mBJ) as the exchange correlation. Our results show a similar half-metallic ferromagnetic ground state for both materials. From the electronic properties, it is found that Sr2CrYO6 has a direct band gap at (Γ-Γ) direction and Sr2CrLaO6 has an indirect band gap at (Γ-W) direction. Furthermore, we have computed the optic and thermodynamic properties which are investigated for the first time. Consequently, the magnetic, optoelectronic, and thermodynamic properties show these compounds are promising for high technological applications, namely spintronic materials. 相似文献
73.
Molecular dynamics simulations have been used to investigate the confinement packing characteristics of small hydrophilic (N-acetyl-glycine-methylamide, Nagma) and hydrophobic (N-acetyl-leucine-methylamide, Nalma) biomolecules in large diameter single-wall carbon nanotubes (SWCNTs). We find that hydrophilic biomolecules easily fill the nanotube and self organize into a geometrical configuration which reminds the water structural organization under SWCNT confinement. The packing of hydrophilic biomolecules inside the cylinder confines all water molecules in its core, which enhances their mobility. Conversely, hydrophobic biomolecules accommodate into the nanotubes with a trend for homogeneous filling, which generate unstable small pockets of water and drive toward a state of dehydration. These results shed light on key parameters important for the encapsulation of biomolecules with direct relevance for long-term storage and prevention of degradation. 相似文献
74.
David Boldrin Freya Johnson Ryan Thompson Andrei P. Mihai Bin Zou Jan Zemen Jack Griffiths Patrik Gubeljak Kristian L. Ormandy Pascal Manuel Dmitry D. Khalyavin Bachir Ouladdiaf Navid Qureshi Peter Petrov Will Branford Lesley F. Cohen 《Advanced functional materials》2019,29(40)
Multicomponent magnetic phase diagrams are a key property of functional materials for a variety of uses, such as manipulation of magnetization for energy efficient memory, data storage, and cooling applications. Strong spin‐lattice coupling extends this functionality further by allowing electric‐field‐control of magnetization via strain coupling with a piezoelectric. Here this work explores the magnetic phase diagram of piezomagnetic Mn3NiN thin films, with a frustrated noncollinear antiferromagnetic (AFM) structure, as a function of the growth induced biaxial strain. Under compressive strain, the films support a canted AFM state with large coercivity of the transverse anomalous Hall resistivity, ρxy, at low temperature, that transforms at a well‐defined Néel transition temperature (TN) into a soft ferrimagnetic‐like (FIM) state at high temperatures. In stark contrast, under tensile strain, the low temperature canted AFM phase transitions to a state where ρxy is an order of magnitude smaller and therefore consistent with a low magnetization phase. Neutron scattering confirms that the high temperature FIM‐like phase of compressively strained films is magnetically ordered and the transition at TN is first‐order. The results open the field toward future exploration of electric‐field‐driven piezospintronic and thin film caloric cooling applications in both Mn3NiN itself and the broader Mn3AN family. 相似文献
75.
Abdelkebir Semia Mayouf Abdelhalim Mayouf Faiza Zoubiri Bachir Devers Thierry 《Microsystem Technologies》2019,25(3):797-810
Microsystem Technologies - In this paper, a new metamaterial-inspired high frequency surface wave antenna is designed. An artificial magnetic conductor surface is introduced into the near field... 相似文献
76.
It is well known that the nonparametric estimation of the regression function is
highly sensitive to the presence of even a small proportion of outliers in the data. To solve
the problem of typical observations when the covariates of the nonparametric component
are functional, the robust estimates for the regression parameter and regression operator
are introduced. The main propose of the paper is to consider data-driven methods of
selecting the number of neighbors in order to make the proposed processes fully automatic.
We use the 相似文献
77.
We demonstrated mainly some of the different parameters effects -as a function of temperature-as window layers, thickness, and doping of the various layers (emitter, base and BSF) on the performances of InGaP/GaAs solar cell. First, we have varied the molar fraction of different layers; their thickness and the doping of both emitters and bases. We have registered the result of each variation until obtaining optimal parameters. In a second stage, we have simulated the InGaP/GaAs cell without window layers which results in η = 12.47% and η = 22.14% for eliminating top and bottom windows respectively. Then, the elimination of layer BSFs(back surface field) on the back face of the considered cell causes a remarkable decrease in open circuit voltage Voc and output η which reached 1.57 V and 11.95% respectively. In a last stage, we optimized and simulated the performances of the InGaP/GaAs dual-junction solar cell for its optimal parameters while varying its operation temperature from 300 K to 375 K with an increment of 25 °C using a virtual wafer fabrication TCAD Silvaco. The optimization at 300 K led to the following results Icc = 15.19 mA/cm?2, Voc = 2.53 V, FF = 91.32% and η = 25.43% which are close with those found in literature for In(1?x)Ga(x)P(x is molar fraction: x = 0.5). Therefore, we could determine the critical parameters of the cell and optimize its main parameters to obtain the highest performance for a dual junction solar cell. This work will pave the way with new prospects in the field of the photovoltaic. The structure simulation will simplify the manufacturing processes of solar cells; will thus reduce the costs while producing high outputs of photovoltaic conversion. 相似文献
78.
79.
Benali Boutabout Mourad Chama Bel Abbes Bachir Bouiadjra Boualem Serier Abdelkader Lousdad 《Computational Materials Science》2009,46(4):906-911
The purpose of this paper is to understand the combined effect of thermal and mechanical loading on the initiation and behaviour of sub-interface crack in the ceramic. In this study a 2D finite element model has been used to simulated mixed mode crack propagation near the bimaterial interface. The assembly ceramometalic is subjected simultaneously to thermomechanical stress field. The extent of a plastic zone deformation in the vicinity of the crack-tip has a significant influence on the rate of its propagation. The crack growth at the joint specimen under four-point bending (4PB) loading and the influence of residual stresses was also evaluated by the maximum tensile stress criterion. The J-integral at the crack tip is generally expressed by the thermomechanical local stresses. The results obtained show the effect of the temperature gradient ΔT, the size of the crack and the applied stresses on the J-integral. 相似文献
80.
Ali Merdji Rajshree Mootanah Bel Abbes Bachir Bouiadjra Ali Benaissa Laid Aminallah El Bahri Ould Chikh Sam Mukdadi 《Materials science & engineering. C, Materials for biological applications》2013,33(2):691-698
The human tooth faces different stresses under environments of different loading conditions, these loading produces major factors in weakness of the tooth and bone structure. The need to save natural teeth has prompted the development of novel and complex techniques in endodontology, prosthodontics and periodontology. Despite a poor long-term prognosis and some prejudice to local bone, considerable efforts have been exerted for the realization of these techniques. Nowadays, the 3D finite element analysis (FEA) is one of the more recently used techniques for stress analysis in single human tooth under different loading cases. The von Mises stress distribution indicated that the greatest effort area of tooth lies at the base of crown up to the gingival line with varying intensities in the different loading cases. The highest stress in the cortical bone was predominantly found around the cervical region of the tooth and lowest in the cancellous bone and periodontal ligament (PDL). The PDL is a soft tissue, and it could function as an intermediate cushion element which absorbs the impact force and uniformly transfers the occlusal forces into the surrounding bone. 相似文献