Optimized Lattice Parameters Research Articles

The broad-spectrum biocide triclosan trigonal crystal: Experimental and DFT-calculated structural, electronic and optical properties

Triclosan, a member of the broad-spectrum biocide class, has seen widespread usage in various household and healthcare-related products worldwide over the past 35 years. However, its extensive use has raised concerns regarding health and environmental impacts. Notably, there is a notable gap in our understanding of the solid-state properties of triclosan, encompassing both experimental aspects, such as optical absorption, and theoretical insights. Expanding upon the established trigonal crystal structure of triclosan, this study employs experimental techniques including X-ray and photoacoustic-based optical absorption, alongside density functional theory (DFT) calculations, to elucidate its structural, electronic, and optical characteristics. Employing the generalized gradient approximation (GGA) DFT exchange-correlation functional and accounting for dispersion effects, optimal lattice parameters were determined with small deviations from experimental measurements (<∼2.2%). The calculations predict that the triclosan trigonal crystal has very close direct band gaps of about 3.44 eV, almost identical to the value of 3.45 eV derived from photoacoustic optical absorption measurements. Analysis of the calculated optical absorption and complex dielectric function underscores the optical isotropy of solid state triclosan. Furthermore, effective mass computations, in conjunction with the band gap results, suggest that triclosan displays electronic characteristics akin to those of a wide direct gap semiconductor.

First-principles calculations to investigate physical properties of oxide perovskites LaBO3 (B[dbnd]Mn, Fe) for thermo-spintronic devices

Oxide perovskite LaBO3 was extensively examined using first principles computations with density functional theory. Various exchange-correlation functionals were applied to investigate several of its physical properties. The compound's stability was validated through energy optimization in both ferromagnetic and non-magnetic phases, revealing that the ferromagnetic phase is more energetically stable. With the optimized lattice parameter, we explored various electronic, mechanical, magnetic, and thermodynamic properties. According to the GGA + U approximation, LaMnO3 and LaFeO3 exhibit half-metallic and semiconductor characteristics, respectively. The elastic constants, along with the elastic moduli (Y, B, and G) and Vickers hardness (Hv) number, were calculated to assess the mechanical properties of both compounds. Our simulation confirmed the ductile nature of the material by analyzing the Cauchy pressure, Poisson's ratio, and Pugh ratio. Additionally, thermodynamic parameters, including thermal expansion, specific heat capacity, and Debye temperature, were computed using the quasi-harmonic Debye model. The study's findings suggest that these materials are suitable for thermo-spintronic devices.

Performance and sensitivity mechanism of the 1,3,5-trinitro-2,4,6-trinitroaminobenzene (TNTNB)

Recently, a new type of high-energy explosive (TNTNB) has been synthesized. Before fully understanding its detonation performance and safety features, it is necessary to conduct certain studies on its basic physical properties. For this purpose, we have employed first-principles methods to investigate the structural, electronic, vibrational, and thermal properties of TNTNB. The optimized lattice parameters of TNTNB crystals differ from the experimental values by less than 2 %. The electronic properties calculation results show that TNTNB has an indirect bandgap of 2.1508 eV. The phonon dispersion and density of phonon states indicate that its phonon bath modes region is 0–245 cm−1, and the doorway modes region is 245–735 cm−1. Additionally, the calculated energy transfer rate is 3.460 × 1012 J/K/mol, and the phonon-vibration coupling coefficient is 3.31. The zero-point energy calculated from the density of phonon states is 1669.06 kJ/mol, and the isochoric heat capacity at 300 K is 1441.48 J/K/mol.

Morphological, structural, and electronic properties of green synthesized ZnO nanoparticles by experimental and DFT+U method – A review

In these decades, researchers have paid much attention to green synthesis methods because of their low cost and eco-friendliness. Among all other semiconductors, ZnO nanoparticles have huge applications in optoelectronics devices, solar cells, photocatalysis, transistors, etc. This review article explains the green synthesis methods and factors affecting the morphology of ZnO nanoparticles. The morphology shows different structures such as nanowires, cubic, hexagonal, flower-like structures, etc. The XPS peaks Zn-2p1/2, Zn-2p3/2, and O-1S suggest that the synthesized nanoparticles are ZnO. The theoretical review part explains the electronic and structural properties of wurtzite ZnO nanoparticles. The implementation of the Hubbard-U scheme in the d and p shells using Local Density Approximation (LDA) and Generalized Gradient Approximation (GGA) shows the drastic change in the electronic and structural properties of ZnO nanoparticles. The optimized lattice parameters and band gap using Hubbard parameters by different DFT codes are tabulated. Also, we compared computational and experimental results.

Theoretical Investigation of The Properties of LiRuAs Semi-Heusler Alloy via Density Function Theory

The structural, thermal, electronic and elastic properties of LiRuAS semi Heusler alloy were investigated using a generalized gradient approximation (GGA) approach, which employs a density functional theory (DFT) to examine the alloy's optimized equilibrium lattice parameter. The optimized lattice parameter was found to be 5.601 Å. The results of the calculations indicate that the alloy exhibits mechanical stability, flexibility, non-magnetic conductivity, malleability, compressibility, and anisotropy.

Structural, phonon, optical, electronic, and thermodynamic properties of NpX (X = S, Se, Te) chalcogenides: A DFT study

Binary chalcogenides with small Reststrahlen bands in the far infrared and microwave region make them intriguing for IR sensors and radar communication purposes. In this study, we have theoretically investigated the structural, phonon, electronic, optical, IR optical and thermodynamic properties of NpX, where X = S, Se, and Te chalcogenides. The face-centered cubic structure is relaxed to determine the optimized lattice parameters which increased with an increase in the size of involving chalcogen atom. Band structure reveals their metallic nature. The significant contribution of d and f-states of Np and p-states of chalcogens in band formation is evident from the density of state plots. The detailed analysis of optical parameters including real and imaginary parts of dielectric constant and refractive index, optical conductivity, and optical loss exhibit high absorption in the IR region.

A DFT+U Study of the Structural and Electronic Properties of Zinc Doped Anatase TiO2 Nanomaterial

This work reports a theoretical study on the structural and electronic properties of the anatase phase of titanium dioxide (TiO2) within the framework of density functional theory corrected for on-site coulomb interactions in strongly correlated materials (DFT+U). The exchange correlation was described by local density approximation (LDA). The optimized lattice parameters obtained for the pure anatase TiO2 agree with the experimental data. Our results revealed that, after the zinc doping, the structure didn't change but there was a little expansion in the volume of the pure material. It was found that the doped structure's stability increases as the concentration of the dopant increases, but all the doped structures are stable. However, introducing the zinc dopant has significantly reduced the band gap of the pure anatase by 80.7 %, 80 %, and 78.6 % due to 0.25, 0.5, and 0.75 doping concentrations, respectively. This implies that the band gap energy increases as the doping concentration increases.

Lead free A2NaInI6 (A = Cs, Rb, K) double perovskites for optoelectronic and thermoelectric applications

Alkali metal substitution in double perovskites is an appropriate approach to deliberate tuning of band edges which play a vital role in bandgap engineering of emerging semiconducting materials. Here we tuned the optoelectronic behavior by carefully engineering the band edges in A2NaInI6 (A = Cs, Rb, K) systems and by tuning the alkali atoms at A site using density functional theory based WIEN2K code. First of all, the unit cell is relaxed to find the optimized lattice parameters. The substitution of smaller-sized cation at the A site leads to the reduction in lattice parameter which shifts the absorption edge towards a shorter wavelength and reduces the bandgap energy. The value of bandgap energy is noticed at 1.60 eV for Cs2NaInI6 which increases to 1.65 and 1.70 eV for Rb2NaInI6 and K2NaInI6 respectively. The computation of the elastic constant’s dependent modulus of elasticity and the Pugh and Poisson ratio confirm their brittle nature. Their viability for solar-thermoelectric generators is carried out by computing the temperature-dependent transport parameters using the BoltzTrap code showing the potential of these systems for solar thermoelectric generators.

Synthesis of lithium doped magnesium ferrites and their vibrational and magnetic properties: Correlation of experimental and density functional theory

Recently, there has been an increased focus on investigating the possible use of ferrite nanoparticles as magnetic memory devices. In this study, we report on the structural, microstructural, Raman, density functional theory and magnetic characteristics of Mg1-xLixFe2O4 (x = 0, 0.15, 0.3, 0.45, 0.5 and 0.75). Samples were synthesized by solution combustion synthesis method. Samples were subjected to characterize X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman Spectra. XRD reveals that all synthesized samples show a single phase formation and unit cell volume, crystallite size varied with an increase in Lithium-ion concentration. SEM micrographs confirmed the porous nature increases with the rise of Li concentration. Particles are agglomeration and spherical type of nature was confirmed by TEM images. Further, Raman Spectra confirms the spinel cubic structure of MgFe2O4 nanoparticles belongs to the Fd3m space group. Despite the fact that the full unit cell has 56 atoms (Z = 8), the smallest Bravais cell consists of only 14 atoms (Z = 2). Consequently, in order to understand this effect, the electronic structure of pure and doped models was investigated through the Band Structure and Density of States (D.O.S.) profiles. First the crystalline structure of pure and Li-doped MgFe2O4 was analyzed based on the optimized lattice parameters and M − O (M = Mg, Li and Fe) bond distances. The band-gap was computed to be 2.54 eV being a direct transition between two points, in an excellent agreement with the experimental measurements. To investigate the temperature dependent magnetic properties, the M − H loops of Li doped MgFe2O4 nanoparticles traced at below and above room temperature over the applied magnetic field ±60 kOe. The M − H loops recorded at above and below room temperature demonstrated that the ferromagnetic nature of the sample. Further, the magnetic properties was investigated using temperature dependent FC and ZFC magnetization measurements. Above room temperature, the ZFC and FC curves show irreversibility and split at certain temperatures, as well as a broad maximum in ZFC curves at blocking temperature (TB). Saturation magnetization (Ms) values are higher at 15 K compared to 300 K, attributed to reduced thermal fluctuation. Our results suggest that synthesized materials are useful for room temperature magnetic memory device application.

A DFT study of structural, electronic, mechanical, optical, and hydrogen storage properties of quaternary hydride phase Li4BN3H10

In this paper, we investigated the structural, electronic, mechanical and optical properties of Li4BN3H10 using the ultra-soft pseudopotential method which is based on the density functional theory (DFT) with CASTEP code. The optimized lattice parameters of Li4BN3H10 correlate well with the theoretical calculations and experimental measurements that are currently available. Using elastic constants, the material's stability was verified. Based on the elastic constants, we discovered several mechanical features of the material. Between 0 and 20 eV, optical spectra calculations are made, taking into account the real and imaginary parts of the dielectric function ε(ω), reflectivity R(ω), index of refraction n(ω), coefficients of extinction k(ω) and absorption α(ω). The dielectric function is wide close to the middle ultraviolet (4.13–6.20 eV). The extinction coefficient of the Li4BN3H10 has the ability to worn for implements like Bragg's reflectors, optical and optoelectronic equipments. The optical parameters of Li4BN3H10 disclose that our working constructions have an elevated dielectric constant, with a greatest absorption in the visible range holding out over 1.49 × 105 cm−1 Li4BN3H10 is deemed to be an appropriate material for optoelectronic applications based on calculated optical results. The gravimetric hydrogen storage capacities of Li4BN3H10 compound is 11.06 wt %. These promising capacities exceed the 6.5 wt % target set by the US Department of Energy for 2025.

Electronic, Elastic, Optical, and Thermodynamic Properties Study of Ytterbium Chalcogenides Using Density Functional Theory

In this study, the structural, electronic, optical, elastic, and thermodynamic properties of Ytterbium chalcogenides YbX (X = S, Se and Te) were computed within the first principles using generalized gradient approximation (GGA) as implemented in the pseudopotential plane wave approach. The equilibrium total energy for YbX (X = S, Se, and Te) was calculated as a function of the energy cutoff, k-point grid, and lattice parameter. An optimized lattice parameter of 5.6, 5.66, and 6.136 Å were calculated for YbS, YbSe, and YbTe, respectively. The energy band gaps of YbS, YbSe, and YbTe computed are 1.14, 1.32, and 1.48 eV, respectively. In addition, the low band gap (less than 3 eV) for ytterbium chalcogenides indicated that they may have potential applications in photovoltaic cells and laser diodes. Moreover, the negative dielectric function value for a certain frequency range indicates that these compounds are suitable for specific optical and microwave circuit applications. The result of elastic and thermodynamic property computation reveals that ytterbium chalcogenides are mechanically and thermodynamically stable, which can be useful in a variety of electronic device applications.

Structural, electronic and thermoelectric properties of monolayer TiSe2.

In this work the first-principles calculations of the structural, electronic and thermoelectric properties of monolayer TiSe2 are presented. The optimized lattice parameter of monolayer TiSe2 shows excellent agreement with the experimental value. The computed band structure and density of states calculations predict metallic nature of monolayer TiSe2 with overlapping of 0.44eV between the lowest conduction band and top valance band at high symmetry point M. The position of pseudogap formed by Ti-3d orbitals near the Fermi level confirms the mechanical stability of monolayer TiSe2. Due to the influence of positive strain (tensile strain), the Ti-Se bond length increases and the layer height decreases. The applied tensile strain changes the metallic nature of TiSe2 into a semiconductor with opening of bandgap. It has also been observed that the positions of conduction band minima and valance band maxima change with strain. The charge analysis shows that charge transfer from Ti to Se atom increases when tensile strain is applied, while an opposite trend is observed with compression. The computed thermoelectric coefficientsi.e. Seeback coefficient, power factor and figure of merit are in good agreement with the experimental data.The temperature dependence of these coefficientsis also reported. The density functional theory based calculations are reported employing the PBE-GGA ansatz using the plane wave-pseudopotential method embodied in the Quantum ESPRESSO package. The self-consistent field calculations are performed over a dense Monkhorst-Pack net of 12 × 12 × 1k-points. The energy convergence criteria for the self-consistent field calculation were set to 10-6 Ry/atom with a cutoff energy of 90 Ry. The thermoelectric properties are computed by combining the band structure calculations with the Boltzmann transport equation using Boltztrap2 peckage.

The mechanical properties of (NbMoTaW)Si2 from a first-principles calculations

The realm of ceramic materials has seen a surge in interest directed towards high entropy disilicides due to their exceptional properties. Using the methodologies of density functional theory (DFT) and the special quasi-random structure (SQS), we have delved into the examination of structural stability and the inherent elastic properties of (NbMoTaW)Si2. The available experimental data and the optimized lattice parameters coincide very well. The thermodynamic stability observed in all high entropy ceramics, specifically (NbMoTaW)Si2 disilicides, can be attributed to their negative formation enthalpies. The present results of elastic parameters show that the strength/hardness of (NbMoTaW)Si2 are larger due to the higher bulk and shear moduli. The Vickers hardness of (NbMoTaW)Si2 is higher than the average value of component binary metal silicide, indicating solid solution strengthening effect. The mechanical anisotropy of the (NbMoTaW)Si2 reveals the significant difference in various directions on different crystalline planes. Conducting theoretical research holds significance in facilitating the synthesis of enhanced high entropy disilicides ceramics. Furthermore, such studies are crucial in advancing the evolution and practical utilization of high entropy materials.

A first-principles investigation on the structural, electronic and optical characteristics of tetragonal compounds XAgO (X = Li, Na, K, Rb)

First-principles calculations employing the density functional theory full-potential (linearized) augmented plane-wave plus local orbitals (FP-(L)/APW + lo) method were conducted to investigate the structural, electronic and optical characteristics of silver-based ternary oxides XAgO (X = Li, Na, K, and Rb). The GGA-PBEsol and TB-mBJ functionals were employed to describe the exchange-correlation potential. The optimized lattice parameters and atomic positions obtained from the calculations exhibit good agreement with both theoretical predictions and experimental measurements. Various exchange-correlation functionals were employed to evaluate the electronic properties, revealing that the newly developed Tran–Blaha modified Becke–Johnson functional yields a significant improvement in the band gap value. All XAgO compounds under consideration are categorized as semiconductor materials where the band gap value decreases as the atomic size of the X element increases. The study also explored the total and site-projected l-decomposed densities of states. Additionally, the complex dielectric function, refractive index, extinction coefficient, reflectivity, and loss function spectra were calculated for the incident radiation polarized parallel to both the [100] and [001] crystalline directions. The interband transitions that contribute effectively to the observed peaks in the imaginary part of the dielectric function were identified.

Numerical simulation studies of the new quaternary MAX phase as future engineering applications: The case study of the Nb2ScAC2 (A = Al, Si) compounds

Recently, MAX phases have attained considerable technological interest owing to their two inherent properties metallic and ceramic properties. This study extensively examined Nb2ScAC2 MAX phases using DFT, to assess the structural, mechanical, electronic, and Thermal characteristics. Firstly, the stability of these two compounds was confirmed through the formation energy, elastic constants (Cij), and phonon band structure, which confirmed their thermodynamic, mechanical, and dynamical stability. The optimized lattice parameters of these compounds were examined and then utilized to calculate the physical properties of the Nb2ScAC2 compound. Our compounds are brittle due to their Pugh’s ratio of less than 1.75. The covalent bonding of the structure revealed by the Poisson ratio is less than 0.25 for the two compounds. The Nb2ScAC2 material is anisotropic, and Nb2ScAlC2 is harder than Nb2ScSiC2.The metallic character of the materials was affirmed by the electronic band structure analysis. Calculated thermal properties such as Debye temperature and minimum and lattice thermal conductivity reveal that both compounds have the potential to enhance their deployment in thermal barrier coating materials. On the other hand, the high melting temperatures indicate that our compounds could potentially be utilized in demanding or severe conditions. Finally, the thermodynamic characteristics, comprising the isochoric heat capacity (Cv) and Debye temperature (ϴD) were analyzed subjected to high temperatures and pressures. The optical constants such as real and imaginary parts of the dielectric function, refractive index and reflectivity, are investigated. The current study recognizes these two compounds as promising candidates for utilization in modern technologies and diverse industries.

An exhaustive analysis of the structural, electronic, magnetic, mechanical, thermal, thermoelectric, optical and thermodynamic properties of AMnBi2 (A = Ca and Sr) via DFT+U and Monte Carlo simulations

Ab initio calculations are used in the present study to analyze the structural, magnetoelectronic, mechanical, thermal, thermoelectric, optical and thermodynamic properties of AMnBi2 compounds (where A = Ca and Sr). The calculations use the density functional theory involving the Full Potential –Linearized Augmented Plane. Wave and the Monte Carlo simulation. We have used the Generalized Gradient Approximation (GGA) with Perdew-Burke-Ernzerhof (PBE) functional for modelling the exchange-correlation potential with Hubbard correction (GGA + U) was employed. The bulk modulus, its first derivative, and the optimal lattice parameters have been found. Both compounds display metallic nature. The electronic transport coefficients have been calculated. The entropy, thermal expansion coefficient, Debye temperature, and heat capacities Cv and Cp are calculated. The elastic constants at zero pressure, the bulk modulus B, and the shear modulus G have been evaluated. The Young's modulus and Poisson's ratio of two compounds have been performed. The Debye temperature is also approximated from the average sound velocity. The Néel temperature, magnetization, and hysteresis cycles are found.

Structural polymorphism, electronic, and optical properties of NaSbS2: A computational approach toward eco-friendly and emerging semiconductor

In this work, the structural polymorphism and electro-optical characteristics of NaSbS2 ternary chalcogenide are realized using density functional theory (DFT). All of the NaSbS2 polymorphs are energetically stable based on the formation energy. The optimized lattice parameters of the monoclinic and triclinic structures and direct electronic bandgap (1.695 eV) of monoclinic structure are consistent with previous studies. Besides, the trigonal and triclinic structures are indirect bandgap (0.916 and 2.015 eV) semiconductors observed from electronic band structure. The higher degree of ionicity between Na and S atoms while strong covalency in the Sb-S bonds are confirmed from the charge and bond analysis. The lower value of electron-hole effective masses indicates higher carrier mobility leading to outstanding electrical conductivity. It was suggested that the polymorphs would be extremely desired to design Bragg reflectors and waveguides based on the reported high value of the real part of the dielectric constant and refractive index. These polymorphs will contribute significantly to being used as absorbers, as evidenced by their high absorption coefficient and photoconductivity and lower transmittance. All the polymorphs reflect significant optical anisotropy and birefringence, rendering them excellent for usage in the fabrication of waveguides, polarizers, and photonic devices. Thus, the projected good features of NaSbS2 polymorphs would play an essential role in the development of lead-free photovoltaic devices, including solar cells and other optoelectronic devices, and would be able to provide practical information for future theoretical and experimental studies.

Physical properties of Be-based fluoroperovskite compounds XBeF3 (X = K, Rb): a first-principles study

In this study, we used the ab-initio computational tools as implemented in the CASTEP code to explore the effects of pressure on the structural, elastic, electronic, thermodynamic and optical properties of the fluoroperovskite compounds XBeF3 (X = K, Rb) based on Being. Exchange–correlation interactions were modeled using the GGA-PBEsol functional. The ground state of the title materials was characterized by calculating the optimized lattice parameter, the bulk modulus B and its pressure derivative, and the Goldsmith tolerance factor. These materials exhibit structural stability in the cubic structure even when subjected to significant pressure levels, extending up to 18 GPa. The analysis of numerical assessments of single-crystal elastic constants (Cij ), polycrystalline elastic moduli, namely shear modulus (G), Young’s modulus and Poisson’s ratio, as well as the anisotropy factor (A), highlights the mechanical stability, elastic anisotropy and ductility of considered the compounds. The thermodynamic properties of these materials were studied through the Debye quasi-harmonic model. Analysis of energy band structures and density of states spectra shows that XBeF3 (X = K, Rb) is insulating in nature, with band gaps of 7.99 and 7.26 eV, respectively. Additionally, we calculated the linear optical spectra, including dielectric function, absorption coefficient, refractive index, optical reflectivity, and energy loss function. Based on the results obtained, these materials could be used in various optoelectronic devices operating in the UV spectrum and in energy storage devices.

Study of structural, electronic and optoelectronic properties of the Half Heusler LiMgZ (Z = N, P or Sb) materials: DFT and TDDFT approaches

In this paper, we illustrate the structural, electronic, and optoelectronic properties of LiMgZ (Z = N, P or Sb) half-materials using two methods: DFT and TDDFT. To achieve this goal, we have performed the DFT method under the Quantum Espresso package. Both calculation methods have been done under the approximations: GGA-PBE. In order to determine the optimized lattice parameters of each studied compound, the total energies have been calculated as a function of this parameter. The obtained results show that all the studied compounds are indirect band gap semiconductors, except for the LiMgSb material which shows a direct band gap. Moreover, the calculated band gap energy values are 2.30 eV, 2.15 eV, and 1.1 eV for LiMgP, LiMgN, and LiMgSb respectively. It is clear that this latter compound is more suitable for photovoltaic applications.

Exploring the physical properties of quaternary fluoro-elpasolites A2 NaInF6 (A = Cs,Rb)compounds for prospective technological applications

The double perovskite materials possess exceptional traits that make them highly suitable for energy-related applications, owing to their eco-friendliness, efficiency, and lack of toxicity. Using the density functional theory implemented in WIEN2K, we conducted a thorough examination of the electronic, structural, optical, and elastic characteristics of A2NaInF6 (A = Cs, Rb) double perovskite materials. The energy formation and the Birch-Murnaghan equation of state fitting curve guarantee both thermodynamic and structural stability. The optimized lattice parameters obtained from our computations are in agreement with the experimental values for the relevant compounds. For calculating the electronic and optical properties of both materials, the widely used TB-mBJ (Trans Blaha modified Becke–Johnson) approximation is utilized. The replacement of ‘Cs’ with ‘Rb’ results in the tuning of the band gap from 7.70 eV to 5.01 eV. After analyzing the mechanical properties, it is anticipated that both materials exhibit elastic stability, brittleness, and relatively lower hardness. The optical properties are computed, analyzed, and presented across a broad energy range of 0–30 eV of incident photon energy. The absorption coefficient, which is a part of the optical properties, highlights the potential of these materials as fundamental components for optoelectronic devices operating in the extreme ultraviolet (XUV) region. The outcomes of our study could provide valuable insights for the development of high-performance optoelectronic devices.