Energy Loss Function Research Articles

Exploring the impact of hydrostatic pressure on the essential physical properties of BaTiO3 perovskite: A first principles quantum investigation and prospects for optoelectronic and thermoelectric applications

This research investigates how externally applied hydrostatic pressure ranging from 0 to 100 GPa impacts the cubic BaTiO3 perovskite compound through computational simulations. The results reveal that the bandgap value increases and shifts in the visible spectrum by applying pressures from 0 to 100 GPa. The absence of negative frequencies in the phonon dispersion confirms the dynamic stability of cubic BaTiO3 compound. The BaTiO3 maintains its cubic phase and exhibits remarkable mechanical stability with ductile behavior when subjected to high pressures. The optical properties of cubic BaTiO3 compound have been meticulously investigated utilizing complex dielectric function, complex refractive index, optical reflectivity, absorption coefficient, optical conductivity, and energy loss function across the energy spectrum up to 50 eV. The study identifies maximum absorption peaks in the UV region. So, cubic BaTiO3 compound under the effect of different pressures is suitable for broadly tunable phosphor material for energy-efficient w-LEDs, optoelectronic and thermoelectric applications.

Direct Calculations of the Dielectric and Optical Parameters of Some Compound Semiconductors: A Study Using the Lorentz Oscillator and Wemple-DiDomenico Models

The Lorentz single oscillator model is widely utilized to describe the electron-phonon interaction in solids. The use of this model to calculate the dielectric function and optical parameters of compound semiconductors represents a novel approach in materials science which may lead to develop new materials with tailored optical properties and consequently can offer vast applications in areas such as quantum computing and quantum information processing. This work presents direct calculations of the complex dielectric function and some optical parameters, such as refractive index, extinction coefficient, and reflectivity for some selected III-V and II-VI compound semiconductors using Lorentz oscillator model. The dielectric and optical dispersion parameters among the infrared and visible electromagnetic spectra follows the so-called Transmission-Absorption-Reflection-Transmission (TART) trend. The TART curve provides information about how a material interacts with light at different wavelengths, which is crucial for understanding and optimizing various optoelectronic devices. Moreover, dielectric loss functions such as loss tangent, surface energy loss function and volume energy loss function are investigated. The refractive index dispersion is analyzed using Wemple–DiDomenico single effective oscillator model and Sellmeier equation. The energy of the effective single oscillator (Eo) and the dispersion energy (Ed) are estimated.

A comparative spin orbit coupling DFT study of opto-electronic properties of [formula omitted] and [formula omitted] bulk crystal

Bi2Se3 and Bi2Te3 are the ideal candidate for spintronics and many other novel applications due to their strong opto-electronic properties. These materials are regarded as topological insulator as they portray band inversion which is considered to be a key signature of topology. Moreover, because of their superior opto-electronic qualities, Bi2Se3 and Bi2Te3 are intriguing in the realm of optical and electronic applications. This paper compares the optical and electronic characteristics of Bi2Te3 and Bi2Se3 in the framework of density functional theory taking PBE-GGA and mBJ-GGA as exchange correlation potential. The analysis of band structure and density of states (DOS) confirms the gapped nature without and with SOC calculation. The introduction of SOC gives the accurate result which matches with the experimental figure. Optical properties including reflectivity, absorption coefficient, energy loss function, refractive index, extinction coefficient, and optical conductivity are analyzed without and with SOC. We have also calculated birefringence, dichroism, and the optical skin depth which has not been reported yet for those compounds. The spectroscopic limited maximum efficiency (SLME), which theoretically determines the power conversion efficiency (PCE) of solar cells is also calculated. Based on the optical and electronic properties, possible uses of Bi2Se3 and Bi2Te3 are discussed without and with SOC effect.

First-principles calculations of structural, magneto-electronic, mechanical, optical and thermoelectric properties of novel quaternary Heusler alloys type ZrCoYAs (Y= Fe and Mn)

To determine the structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of novel quaternary Heusler alloys type ZrCoYAs (Y= Fe and Mn), we used DFT with WIEN2k. Our results showed that the ferromagnetic Y-type-III phase is more stable due to the higher negative values of their formation energy. We calculated and discussed the elastic constants Cij, which are used to calculate the mechanical properties. The Spin-polarized band structure and DOS calculations using the GGA-PBE and GGA + U approach display a metallic character. However, using the mBJ-GGA-PBE and mBJ-GGA + U approach show a half-metallic character, a semiconductor for the spin-down channel with a direct band gap of 0.61 eV with mBJ-GGA-PBE and 0.74 eV with mBJ-GGA + U for ZrCoMnAs and a direct band gap of 0.43 eV with mBJ-GGA-PBE and indirect band gap with 0.39 eV with mBJ-GGA + U for ZrCoFeAs, in contrast, the spin-up channel is metallic, with 100 % spin polarization and an integer magnetic moment of 1.00 μB for ZrCoMnAs and 2.00 μB for ZrCoFeAs, obeying the Slater-Pauling rule. The estimated Curie temperatures of ZrCoMnAs and ZrCoFeAs are 204 K using the new model, 421 K using MFA, and 385 K using the new model, 1627 K using MFA, respectively. As exchange-correlation potential, MBJ and MBJ + U provide a better description of the electronic and magnetic properties of ZrCoMnAs and ZrCoFeAs compounds. Important optical properties such as dielectric function, absorption coefficient, refractive index, optical conductivity, reflectivity, and electron energy loss function are calculated in the infrared, visible, and ultraviolet range. The static dielectric function suggests that ZrCoMnAs possesses greater polarizability. Both alloys exhibit similar behavior in the far ultraviolet region range and reach a maximum absorption in the ultraviolet range. The half-metallic character of both alloys is revealed from the reflectivity at zero frequency. The calculation of the thermoelectric properties shows positive Seebeck coefficients, indicating that these Heuslers are p-type. Furthermore, the highest power factor is observed at a temperature of 1400 K. The maximum value of ZT is ∼1.1 at 1400 K for ZrCoFeAs and ZrCoMnAs. These studies show that these alloys may have potential applications in the thermoelectric applications.

Computational Investigation of Structural, Electronic and Optical Properties of Ternary Chalcogenide TLGaQ2 Monoclinic Compounds: a First Principle Study

Purpose: This paper aim to investigate and predict by simulation the impact of the substitution of Q-site atom (Q꞊S, Se) on the TIGaQ2 monoclinic compounds for the first time, along the three main polarizations of the incident wave directions [100], [010] and [001]. Theoretical Framework: This study focuses mainly on ternary chalcogenide compounds TlGaQ2 (Q= S, Se) from ABQ2 family to highlight the objective resources aimed at promising prospects offered for them. Design/Methodology/Approach: A series of ab-initio calculations based on the (PW+PP) method within the density functional theory DFT framework were carried out with CASTEP code for the simulation of their physical properties (structural, electronic-optical). The exchange correlation potential was treated within the generalized gradient approximation (GGA) implemented in the CASTEP code and expressed by the PBE functional. Findings: The equilibrium lattice parameters are in good agreement with the available experimental results. The calculated band structure shows that are direct bandgap semiconductor nature 1.92eV (1.41eV) for TlGaS2 and TlGaSe2 respectively with a great potential for photovoltaic solar cell absorber materials. A set of optical parameters were calculated including the complex dielectric function, the reflective index, reflectivity, the absorption coefficient and loss function. The optical properties obtained revealed very interesting optical properties exhibiting strong optical absorption in UV range up to (~2x105cm-1) for both compounds making them appropriate for photovoltaic solar-cell absorber materials. Furthermore, low reflectivity and energy loss function are shown within in the visible and ultraviolet energy range, allowing them to be promising materials in several optoelectronics applications likes photosensitive devices. Implications: All these findings results show a successful accurately prediction for chalcogenide materials behavior and will be helpful for future studies allowing a better understanding of their potential applications in modern photovoltaic technologies as well as within UV ranges for optoelectronics applications.

Computational study of the structural, mechanical, electronic, optical and thermal properties of BaLiX (X =P, As, Sb) perovskites

This study explores the structural, optical, mechanical, electronic, and thermal characteristics of ionic semiconductor compounds BaLiX (X = P, As, Sb) using Density Functional Theory (DFT). A comprehensive analysis of BaLiX (X = P, As, Sb) is conducted, proving that the estimated and observed lattice parameters coincide well and confirming mechanical stability through elastic stiffness constants. Electronic band structures reveal direct bandgap semiconductor properties with values of 0.70 eV, 0.30 eV, and 0.95 eV for BaLiP, BaLiAs, and BaLiSb, respectively, suggesting specific applications such as mid-infrared photodetectors, terahertz devices, and near-infrared sensors. Optical property analyses, including energy loss function, reflectivity, refractive index, and absorption coefficient, highlight the potential of these materials for optoelectronic and photovoltaic applications. Despite elastic anisotropy, optical anisotropy remains minimal. The materials exhibit potential for use as thermal barrier coatings (TBC) due to their comparatively lower Debye temperature (D), minimum thermal conductivity (Kmin) and lattice thermal conductivity (kph). Moreover, heat capacity calculations and thermal coefficient of expansion are also calculated.

Optical properties of hafnium-dioxide derived from reflection electron energy loss spectroscopy spectra

The optical properties of HfO2 have practical applications. As an important gate dielectric material with high-k dielectric, HfO2 is beneficial to reduce the leakage current of the complementary metal-oxide-semiconductor (CMOS) gate and improves the gate structure. HfO2 also plays a key role in optical coating materials field for its high transmittance in the ultraviolet to near-infrared band, and high laser damage threshold. Therefore, it is of practical significance for the accurate knowledge of optical properties of HfO2. Here we present the optical constants and dielectric function of HfO2 based on the energy loss function (ELF) in the energy loss range of 0–200 eV for nanocrystalline film. Our new data are derived from the analysis of the reflected electron energy loss spectra by using the latest version of our reverse Monte Carlo modelling. Sum rules are used to check the reliability of the new data. We have found that up to 30 eV there are three main peaks, and the first-principles calculation also confirms the three peak structures. A comparison with previous results indicates that the ELF peak positions of HfO2 with different crystal structures are similar, but the peak intensity and shape are different. The heterogenicity of the crystal structure of HfO2 leads to different measurement results for different samples.

Structural, optical and electrical conduction characteristics of PMMA/PVAc/TBAI blended polymers

This study aims to create tetra-n-butylammonium iodide (TBAI) doped poly(methyl methacrylate) (PMMA)/polyvinyl acetate (PVAc) blended polymers for utilize in a diversity of optoelectronic applications. By the casting technique, the films of (PMMA/PVAc/x wt % TBAI) were formed. The structure and morphology characteristics of the blended materials were studied using X-ray diffraction and scanning electron microscopy techniques. The optical transmittance declined to a minimum value when the blend was loaded with 38 wt % TBAI. The blend containing 38 % TBAI exhibits the highest reflectance values in the visible range. The lowest direct optical bandgap energies (4.20 eV) and indirect optical bandgap energies (3.71 eV, 3.13 eV) were achieved when TBAI reached 38 wt%. The addition of TBAI leads to an enhancement of the refractive index values of PMMA/PVAc in the visible spectrum. The effect of TBAI doping amount on the optical dielectric constant, energy loss functions, optical conductivity, nonlinear optical parameters and emitted color of the host blend was explored. The maximum values of the optical dielectric constant and energy loss functions were achieved after the TBAI level reached 38 wt%. The three non-linear optical (NLO) parameters for PMMA/PVAc blended polymers were enhanced as the amount of TBAI increased. An increase in voltage (V) or temperature results in a significant increase in electric current (I). Raising the amount of TBAI doping also caused the electric current to rise irregularly, with the exception of the blend with x = 11 %, where it fell. The samples exhibited the non-ohmic characteristics of the current-voltage (I–V) properties. The conduction mechanism of all blended materials was studied in detail. Finally, the outcomes supported the optical and electric properties studies, which suggested that a range of nanoelectronics applications could make use of the PMMA/PVAc/x weight percent TBAI blended polymers.

Insight into the optoelectronic, and thermoelectric properties for zinc-based TMCs: First principle-based study

In the present study, a comparative investigation was carried out related to the structural, optical, electronic, and thermoelectric nature of three different structural phases for Zinc-based binary chalcogenide material. The newly advanced TB-mBJ (Trans-Blaha modified Becke-Johnson) scheme under the framework of the well-known density functional theory was used to obtain improved and accurate electronic properties and bandgap results. The bandgap calculations show a direct band transition nature having gap values of 1.07 eV, 1.10 eV, and 2.10 eV, for the cubic Rocksalt, the hexagonal wurtzite, and the tetragonal structures of the material respectively. The valence band maxima and the conduction band minima are both positioned at the matching Γ-point revealing a direct band type of behavior in the three studied phases. The computed total and the partial density of state visualize being shifted continuously to high values along the energy axis. The linear optical parameters the dielectric constant ε(ω), the Absorption coefficient, the Energy loss function, the Reflectivity, the Refractive indices, and Extinction coefficients are resolved in detail. The static dielectric constant ε1(0) for the corresponding, α, β and γ-phases of ZnSe decreases due to the bandgap increasing from α - γ phase with an increase in the energy above zero values. The thermoelectric nature of these three different phases is well investigated and discussed in detail. The current work can be a qualitative theoretical study associated with these different phases' structural, optoelectronic, and thermoelectric behavior and their effective technological applications.

A DFT study to explore structural, elastic, mechanical, phonon, electronic and optical properties of halide perovskites AgXF3(X=Be,Ca)$$ {\mathrm{AgXF}}_3\left(\mathrm{X}=\mathrm{Be},\mathrm{Ca}\right) $$ with PBEsol, TB‐mBJ and SCAN functionals

AbstractFirst principles calculations have been performed using full potential linearized augmented plane wave, FP‐LAPW, within Wien2k to elucidate structural, elastic, mechanical, phonon, electronic and optical properties of lead free halide perovskites . The energy volume curve fitting is used to examine structural stability. For structural optimization and mechanical properties, we employed Perdew–Burke–Ernzerhof generalized gradient approximation and PBEsol, revised for solids, exchange and correlation functional. The optimized lattice constant of and is 3.631 and 4.349Å. The elastic constant , and are computed to extract different mechanical parameters like Poisson's ratio, Pugh's ratio, bulk modulus, shear modulus, Young's modulus, anisotropic ratio, Cauchy pressure and shear constant. The mechanical parameters exhibit greater structural, mechanical and dynamical stability of than . The electronic and optical properties are calculated by using TB‐mBJ and SCAN potentials in addition to PBEsol. The electronic band gap of and is 4.71 and 6.01 eV with TB‐mBJ and both perovskites are indirect band gap materials. The optical response of these perovskites against wide range of incident electromagnetic radiation is assessed by calculating absorption, reflection, optical conductivity, dielectric constant, energy loss function and refraction. Strong absorption, high optical conductivity and low reflectivity indicates that and are promising materials for photovoltaic applications.

Spin-polarized electronic, optical, and transport properties of novel Cs2XMoBr6 (X=Na, Li) HDPs: First-principles study

We explored the electronic, optical, and thermoelectric characteristics of novel Cs2XMoBr6 (X=Na, Li) halide-based double perovskites (HDPs) in their monoclinic phase using the density functional theory (DFT). The full-potential linearized augmented plane wave approach was used in the present work. The material Cs2NaMoBr6 was noticed as half-metallic as indicated by an indirect band gap semiconducting nature in the spin-down channel, and with a metallic nature in the spin-up channel. Similarly, the Cs2LiMoBr6 material also revealed a half-metallic nature with an indirect band gap semiconducting nature in spin-down mode and a metallic behavior in spin-up mode. The density of states analysis verifies the electronic behavior of these compounds. To determine the optical characteristics, the optical parameters such as the dielectric functions, the absorption coefficients, the refractivity, the energy loss function, and the reflectivity, have been described. The thermoelectric characteristics of the compounds along the temperature are calculated. It was confirmed that these materials possess extraordinary characteristics that would make them excellent options for influential electronic, optical, and thermoelectric, device applications.

Chemical effect of alkaline-earth metals (Be, Mg, Ca) substitution of BFe2XH hydride perovskites for applications as hydrogen storage materials: A DFT perspective

This study investigated the effect of alkaline-earth metals (X = Be, Mg, Ca) substitution of BFe2XH perovskite materials and the potential applications for hydrogen storage utilizing density functional theory (DFT) approach at the GGA-PBE and the HSE06 methods. The mechanical properties of the studied systems demonstrate the mechanical stability of BFe2MgH, making it the most mechanically robust compound. While the Pugh ratio suggests that BFe2BeH was brittle, while BFe2CaH showed greater ductility, anisotropic factors confirm that all compounds are anisotropic, indicating directional dependence in their properties. The electronic band structure analysis using the HSE06 and the GGA-PBE suggests that the studied perovskites are metallic due to a calculated bandgap of zero. In terms of optical/optoelectronic properties, BFe2MgH exhibits the highest optical conductivity, absorption coefficient, and energy loss function, indicating its superior ability to absorb light and transfer electrons. For practical applications, the hydrogen storage capacity is assessed, with BFe2BeH showing the highest gravimetric and volumetric capacities. These promising results suggest the potential use of BFe2BeH as an efficient material for hydrogen storage.

First Principle calculations for structural and optoelectronic properties of MnNi1-xAgxGe alloys: A DFT study

We investigate the optical and electronic characteristics of parental MnNiGe and doped MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) for photodetector and other electronic applications. First principles are applied to every calculation performed in the context of DFT. The generalized gradient approximation with the Hubbard potential included (GGA + U) has been chosen as the appropriate approximation to handle systems with strongly coupled electrons. The semi-metallic parental MnNiGe and doped MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) is ideal for conducting materials in electronics due to band overlapping, according to our findings. Degenerate doping of Ag into MnNiGe includes spinning the Fermi level, changing the DOS profile, and reducing the density of Fermi level states that allow tunneling from the valence band to the conduction band. An important part of this research is analyzing the refractive index, reflectivity, extinction coefficient, dielectric function, absorption coefficient, and energy loss function of parental MnNiGe and doped MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %). According to our findings, it is possible to create a photo detector based on MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) that can detect light in the visible range (below 500 nm). It has also been found that the MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) exhibits the highest sensitivity to light with a wavelength of 450 nm. Due to its advantageous optical characteristics in the visible and ultraviolet regions, this material could be useful for the development of numerous optoelectronic applications.

Electronic and optical characteristics of CaLiX3 (X = Cl, Br, I) perovskite compounds using the Tran–Blaha modified Becke–Johnson potential

We present the results of a comprehensive investigation using the full-potential linearized augmented plane wave approach to analyze the structural characteristics, electronic structures, and optical spectra of the perovskite compounds CaLiX3 (X = Cl, Br, or I). Various functionals were employed to simulate the exchange–correlation interactions. The calculated equilibrium structural parameters, obtained using the generalized gradient approximation, are consistent with the existing findings in the literature. The computed electronic structures reveal that the Tran–Blaha modified Becke–Johnson potential significantly enhances the bandgap. For all CaLiX3 compounds studied, we predicted an indirect bandgap. Additionally, we observed a gradual decrease in the bandgap as the atomic size of the X element increases. The electronic states constituting the various energy bands were evaluated by computing the partial and total densities of states. In addition, we computed a variety of optical spectra, including the complex dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity, and electron energy loss function. The results demonstrate that a decrease in the bandgap leads to an increase in the zero-frequency limit of the dielectric function ε(0). The origins of the peaks and structures in the optical spectra were identified.

Investigating structural and optoelectronic properties of Cr-substituted ZnSe semiconductors

The optoelectronic and structural characteristics of the Zn1−xCrxSe (0 ≤ x ≤ 1) semiconductor are reported by employing density functional theory (DFT) within the mBJ potential. The findings revealed that the lattice constant decreases with increasing Cr concentration, although the bulk modulus exhibits the opposite trend. ZnSe is a direct bandgap material; however, a change from direct to indirect electronic bandgap has been seen with Cr presence. This transition is caused by structural alterations by Cr and defects forming, which results in novel optical features, including electronic transitions. The electronic bandgap decreases from 2.769 to 0.216 eV, allowing phonons to participate and improving optical absorption. A higher concentration of Cr boosts infrared absorption and these Cr-based ZnSe (ZnCrSe) semiconductors also cover a wider spectrum in the visible range from red to blue light. Important optical parameters such as reflectance, optical conductivity, optical bandgap, extinction coefficient, refractive index, magnetization factor, and energy loss function are discussed, providing a theoretical understanding of the diverse applications of ZnCrSe semiconductors in photonic and optoelectronic devices.

Investigations on structural and opto-electrical characterization of Ag-TCNQ (metal-organic frameworks) as complex thin films for potential device applications

The silver- (7, 7, 8, 8-tetracyanoquinodimethane (Ag-TCNQ) organometallic complex was synthesized chemically as a nano-powder and thereafter deposited as a thin film by thermal evaporation. The monoclinic, needle-like, polycrystalline structure of the Ag-TCNQ complex was analyzed employing x-ray diffraction (XRD) and a scanning electron microscope (SEM). Whereas their chemical structure and stability were explored using Fourier transformation infrared (FTIR) techniques. The findings imply a charge transfer of degree −0.5 between TCNQ° and TCNQ−, as revealed by the shift of the bands of the C≡N stretching and the (C═C-H) bond positioned at 2198 and 824 cm−1, respectively. As well as the optical properties of Ag-TCNQ thin film were studied using spectrophotometric measuring in the wavelength ranging 200 to 2500 nm. The measurement of transmittance and reflectance spectra were employed to calculate the refractive index (n), dielectric constant, absorption index (k), surface and volume energy loss functions, and optical conductivity. In the normal dispersion zone, optical characteristics such free charge carrier concentration, infinity dielectric constant (ε ∞), lattice dielectric constant (ε L), oscillator energy (Eo), and dispersion energy (Ed) were estimated. Furthermore, the optoelectronic nonlinear optical features and electronic transitions for the Ag-TCNQ thin film were assessed. Finally, these findings are promising milestones on the path to providing convincing evidence for the synthesis of stoichiometric thermally stable Ag-TCNQ thin film by conventional thermal evaporation technique that is potential to be utilized in optoelectronic devices applications.

A comprehensive first-principles investigation of structural, electronic, vibrational, optical, thermodynamic and thermoelectric properties of LiZnAs

The structural, electronic, vibrational, optical, thermodynamic and thermoelectric properties of Nowotny–Juza filled tetrahedral semiconductor LiZnAs under high pressure is investigated using the plane-wave pseudo-potential approach in the frame work of density functional theory (DFT) within the generalized gradient approximation (GGA). The calculated lattice constant (a0) and bulk modulus (B0) at ambient pressure are consistent with earlier reported experiment and theoretical results. The variation in Lattice constant, Bulk modulus (B0), Young modulus (Y), Shear modulus (G), Elastic anisotropy factor (A), Poission ratio (μ), Paugh (B/G) ratio and Elastic constants with pressure is analyzed and concluded. Electronic band structure calculations reveal that with applied pressure direct band gap increases and the indirect band gap decreases. Thermodynamic properties reveals thermodynamically stability with pressurize conditions. The real and imaginary parts of the Dielectric function (ε), Refractive index (η), Extinction Coefficient (k), Optical Conductivity (s), Electron/Optical Energy Loss Function (L), Absorption Coefficient (α), Reflectivity (R) at different pressure conditions are correspondingly studied. With applied pressure the absorption spectra shows a blue shift which makes LiZnAs as potential candidates for the application of optoelectronic devices in ultraviolet frequency range. The thermoelectric properties like Seebeck coefficient (S), Electrical conductivity (σ), and Electronic thermal conductivity (k) and Power factor (PF) have been studied as a function of temperature and chemical potential. Positive value of calculated Seebeck coefficient with temperatures ensures the p-type semiconducting nature of LiZnAs. Results provides theoretical guidance for future experimental investigations and industrial applications of LiZnAs.

Computational study to investigate effectiveness of titanium substitution in CaFeH3 perovskite-type hydride: An approach towards advanced hydrogen storage system

In recent years, there has been increased interest in hydrogen storage due to the numerous advantages hydrogen offers as an energy source. This study explores the structural, hydrogen storage, electronic, elastic, mechanical, and optical properties of Ca1-xTixFeH3 through DFT. After Ti substitution in the host material, structure phase transformation occurs: cubic → pseudo-cubic → cubic. Study compounds are thermodynamically stable and experimentally synthesizable according to the calculated negative formation energies. Gravimetric hydrogen storage capacities for different concentrations of Ti (x = 0, 0.11, 0.33, 0.55, 1) were calculated as 2.963, 2.938, 2.843, and 2.753 wt%, respectively. The investigation focuses on understanding the material's BS, Fermi level, and DOS, elucidating its metallic characteristics, and non-zero DOS at the Fermi level contributing to electrical and thermal conductivity. Elemental partial density of states reveals hybridization effects with Ti doping, affecting the valence band's atomic contributions. Using cubic symmetry, C11, C12, and C14 elastic constants were used to describe mechanical characteristics, and the Born criteria were met. Thus, mechanical stability was demonstrated for these compounds. Optical analyses exhibit changes concerning Ti concentrations and energy levels, including absorption spectra, conductivity, reflectivity, dielectric function, refractive index, energy loss function, and extinction coefficient. These findings shed light on the material's response to incident radiation and potential applications in hydrogen storage and optoelectronic devices.

A comprehensive DFT analysis of the physical, optoelectronic and thermoelectric attributes of Ba2lnNbO6 double perovskites for eco-friendly technologies

Within the framework of density functional theory (DFT), as executed in WIEN2k as well as semi-classical Boltzmann transport theory, we reported structural, electronic, elastic, optical, thermoelectric, and thermodynamic properties of the double perovskite compound Ba2InNbO6. To employ the exchange–correlation potential, local density approximation (LDA), the generalized gradient approximation (GGA) with Perdew, Burke and Ernzerhof (PBE) and the modified Becke–Johnson (mBJ) potential is considered. The elastic constants are calculated to check the mechanical stability. The electronic calculations show semiconducting nature with a wide band-gap (3.63 eV) for Ba2InNbO6. The optical properties such as complex dielectric constant ε(ω), refractive index n(ω), reflectivity R(ω), absorption coefficient α(ω), optical conductivity σ(ω) and energy loss function L(ω) described with the incidence frequency. The absorption spectrum shows the behaviour of common semiconductors. The Seebeck coefficient (S) as well as electrical conductivity (σ/τ) also demonstrates the semiconducting nature of the studied compounds by holes having highest particles. The PF was 1.85 × 1012 W K−2 m−1 s−1 at 1200 K and thermodynamic studies, the heat capacity as well as Gruneisen parameter were guessed. Based on obtained results we can ensure that the double perovskite compound Ba2InNbO6 is well suitable for optical and thermoelectric applications.

FP-LAPW calculations of the structural, and optoelectronic properties of vanadium silicide compound for optoelectronic applications

Optoelectronic devices play an essential part in our daily lives by seamlessly integrating optics and electronics, leading to technologies such as smartphones, solar cells, and optical communication. In this study, the structural and optoelectronic characteristics of the hexagonal vanadium silicide are determined using the density functional theory (DFT). The structural parameters such as the zero-pressure bulk modulus B0, its pressure derivative B0′; equilibrium energy, and the volume of the primitive cell at equilibrium V0 are compared with experiment results. The metallic character of VSi2 is confirmed by calculating the density of states and band structure. Moreover, the optical properties like the dielectric function, reflectivity, energy loss function, refractive index, absorption coefficient, and optical conductivity are studied deeply, using the Drude model, within the energy interval from 0 to 14 eV and they are compared with experiment results of a polycrystalline and single crystal. However, the phonon dispersion spectrum shows the presence of imaginary modes, which indicates instability in the structure of vanadium silicide. The results indicate that the VSi2 material has the potential to be used in many applications, including mirrors, glass coatings, optoelectronic devices, optical networks, electronics, optical communications, and waveguide components.