Makine Mühendisliği Bölümü Koleksiyonuhttps://hdl.handle.net/20.500.12960/332024-03-29T06:35:25Z2024-03-29T06:35:25ZOptical Waveguide of Lithium Niobate NanophotonicsAl-Douri, Yarubhttps://hdl.handle.net/20.500.12960/16142024-02-21T07:45:41Z2023-01-01T00:00:00ZOptical Waveguide of Lithium Niobate Nanophotonics
Al-Douri, Yarub
Lithium niobate (LiNbO3) is single crystal and important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators, and various other linear and nonlinear optical applications. Nanophotonics is the study of the behavior of light on the nanometer scale, and the interaction of nanometer‐scale objects with light. It is widely used for photonic applications. Therefore, it is a very promising material to fabricate integrated optical devices due to its superior optical properties are suitable for various optical applications, and it is known as a ferroelectric material used to form waveguides. It has some specific advantages as possibility of producing step index, selective incorporation of dopants, the fabrication of multilayer structures, and the miniaturization and integration of these devices. The planar optical waveguides elucidate the fabrication and integration of several optical components on the same planar substrate, such as interleave filters, beam splitters, variable attenuators, wavelength multiplexers, and optical switchers. The fundamental property of waveguide structures is the relation between the number of the waveguide modes in the function of the layer thickness propagating in the structure and its refractive index because the propagation of light along a waveguide is one of the fundamental and important questions of wave optics. These advantages of planar optical waveguides can be explained as a low connection loss to optical fibers, low transmission loss, high reliability, compact size, and high reproducibility. It is focused on the design and analysis of photonic LiNbO3 using sol–gel method.
2023-01-01T00:00:00ZAb initio investigation of structural, elastic, and thermodynamic characteristics of tetragonal XAgO compounds (X = Li, Na, K, Rb)Allali, DjamelAmari, RabieBouhemadou, AbdelmadjidBoukhari, AmmarDeghfel, BahriEssaoud, Saber SaadBin-Omran, SaadRadjai, MissoumKhenata, RabahAl-Douri, Yarubhttps://hdl.handle.net/20.500.12960/15992024-02-16T11:36:53Z2023-01-01T00:00:00ZAb initio investigation of structural, elastic, and thermodynamic characteristics of tetragonal XAgO compounds (X = Li, Na, K, Rb)
Allali, Djamel; Amari, Rabie; Bouhemadou, Abdelmadjid; Boukhari, Ammar; Deghfel, Bahri; Essaoud, Saber Saad; Bin-Omran, Saad; Radjai, Missoum; Khenata, Rabah; Al-Douri, Yarub
The present research utilizes ab initio computations to examine the thermodynamic, structural, and elastic characteristics of XAgO ternary oxides, where X signifies Li, Na, K, and Rb.The GGA-PBE and GGA-WC functionals were used to calculate the ground-state lattice parameters and atomic position coordinates of the title materials. The calculated results were in good agreement with both experimental measurements and theoretical predictions. This suggests that the GGA-PBE and GGA-WC functionals are accurate for describing the structural properties of the material under study.This study offers computational predictions for the elastic properties of monocrystalline structures and polycrystalline aggregates of XAgO compounds. These predictions encompass various key parameters, including single-crystal elastic constants, Young’s modulus, bulk modulus, Lame coefficients, Poisson’s ratio, shear modulus, and Debye temperature. Additionally, the quasi-harmonic Debye approximation is utilized to explore the temperature-dependent behavior of bulk modulus, Debye temperature, volume thermal expansion coefficient, and isobaric and isochoric heat capacities over an extensive temperature range, while maintaining constant pressures. The results obtained from this model are found to be highly successful in accurately predicting the behavior of these properties.
2023-01-01T00:00:00ZAb initio predictions of pressure-dependent structural, elastic, and thermodynamic properties of CaLiX3 (X = Cl, Br, and I) halide perovskitesAllaf, HatemRadjai, MissoumAllali, DjamelBouhemadou, AbdelmadjidEssaoud, Saber SaadBin-Omran, SaadKhenata, RabahAl-Douri, Yarubhttps://hdl.handle.net/20.500.12960/15852024-02-05T07:38:27Z2023-01-01T00:00:00ZAb initio predictions of pressure-dependent structural, elastic, and thermodynamic properties of CaLiX3 (X = Cl, Br, and I) halide perovskites
Allaf, Hatem; Radjai, Missoum; Allali, Djamel; Bouhemadou, Abdelmadjid; Essaoud, Saber Saad; Bin-Omran, Saad; Khenata, Rabah; Al-Douri, Yarub
In this comprehensive investigation, we undertook an ab initio exploration of the pressure-dependent structural, elastic and thermodynamic attributes of lithium-based halide perovskite compounds, namely CaLiCl3, CaLiBr3 and CaLiI3. Our analytical approach encompassed a diverse set of parameters, and the main conclusions and implications of our study are summarized as follows: (i) Calculated values of formation enthalpy and cohesion energy were determined for these perovskite compounds. Our results notably affirm the structural and thermodynamic stability of these materials in their cubic lattice configuration. (ii) Our optimized network parameters, derived from ab initio calculations, demonstrated commendable congruence with previously established theoretical predictions. This agreement strengthens the credibility of our conclusions. (iii) Using strain-constraint methodology, we successfully estimated the single-crystal elastic constants (Cij) of these compounds. This data served as the basis for further analysis. (iv) Using the obtained Cij values, we calculated a complete suite of elastic moduli for CaLiX3 (X = Cl, Br and I) in polycrystalline aggregates. This encompassed bulk modulus, Young's modulus, shear modulus, Lame coefficients, Poisson's ratio and Debye temperature, thus providing valuable information on the mechanical behavior of materials. (v) Using Debye's quasi-harmonic approach, we systematically investigated the temperature dependencies of several essential thermodynamic properties. These include the lattice parameter, thermal expansion coefficient, bulk modulus, Debye temperature, and isochoric and isobaric heat capacities. These analyzes covered a wide temperature range while maintaining fixed selected pressures. Overall, our study aims to provide the scientific community with a robust and comprehensive dataset regarding the structural, elastic, and thermodynamic attributes of CaLiX3 perovskite compounds.
2023-01-01T00:00:00ZStructural, Elastic, Electronic, and Magnetic Properties of Nd-Doped NaScGe Half-Heusler Compound by Ab-Initio MethodBelkharroubi, FadilaBelkilali, WalidKhelfaoui, FrihaBoudahri, FethiZahraoui, MehdiBelmiloud, NawalBentayeb, KaderAbdellah, El Hadj AdelBennoui, Radja Nour El ImeneBelbachir, RaghedAl-Douri Y.https://hdl.handle.net/20.500.12960/15812024-02-05T06:24:35Z2024-01-01T00:00:00ZStructural, Elastic, Electronic, and Magnetic Properties of Nd-Doped NaScGe Half-Heusler Compound by Ab-Initio Method
Belkharroubi, Fadila; Belkilali, Walid; Khelfaoui, Friha; Boudahri, Fethi; Zahraoui, Mehdi; Belmiloud, Nawal; Bentayeb, Kader; Abdellah, El Hadj Adel; Bennoui, Radja Nour El Imene; Belbachir, Raghed; Al-Douri Y.
A comprehensive investigation is conducted on the electronic structure and magnetic properties of half-Heusler NaScGe, which is doped with a rare earth element Nd with different concentrations. The Heusler Na1-xNdxScGe (where x = 0, 0.25, 0.75, and 1) compounds are thoroughly investigated. The examination encompassed structural, elastic, magnetic, and electronic characteristics using the full potential linearized augmented plane wave (FP-LAPW) method. Generalized gradient approximation (GGA) is used to calculate the structural parameters and electronic characteristics. The equilibrium lattice constant and band gap of half-Heusler NaScGe are found to be in good accord with other data. The density of states (DOS) investigation has revealed a semiconductor behavior of half-Heusler NaScGe and half-metallic ferromagnetic properties of quaternary-Heusler Na0.75Nd0.25ScGe, characterized by a moderate band gap in minority spin channel. In addition, the DOS analysis has shown that both ternary half-Heusler NdScGe and QH Na0.25Nd0.75ScGe compounds have exhibited metallic ferromagnetic activity. The work has introduced a novel approach for producing half metals from the semiconductor half-Heusler NaScGe. Quaternary-Heusler Na0.75Nd0.25ScGe is identified as a promising material for applications spintronic.
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