Values Of Formation Energy Research Articles

The electronic structure, optical, and transport properties of novel SrScCu3M4 (M = Se, Te) semiconductors

Abstract The density functional theory is used to investigate the complex relationships between the physical properties of the novel quaternary SrScCu3M4 (M = Se, Te) semiconductors. The computed negative formation energy values of these materials demonstrate their stable nature. The distribution of ELF around chalcogens and Cu atoms shows substantial localization, indicating strong covalent bonding. The phonon dispersion curves show that they possess excellent structure stability with no negative frequencies. The s/p states of Se and s/p/d of Te play minor roles, while Cu-d orbitals possess a considerable influence on the valence band region. The calculated band gaps without SOC for SrScCu3Se4 and SrScCu3Te4 are 1.29, and 0.90, respectively. The predicted energy gap values with SOC for SrScCu3Se4 and SrScCu3Te4 are 1.35, and 0.87, respectively. SrScCu3Se4 is a harder and more compressible material than SrScCu3Te4, as confirmed by its higher bulk modulus. The ε1(ω) values decrease and ultimately become negative, which suggests these materials are reflective. SrScCu3Te4 exhibits plasmon resonance at a high energy domain compared to SrScCu3Se4, resulting in a greater loss function. The current study can establish the potential efficiency of these materials in cutting-edge optoelectronic devices.

Enchanting optical, electronic, and mechanical properties of the sodium based Na2MgSiZ6 (Z = I, Br, Cl) halides have been explored through DFT

Materials. with perovskite structures have been extensively studied due to their remarkable properties, which are important in various aspects of daily life. In the present approach, Na2MgSiZ6 (Z = I, Br, Cl) halides were extensively studied, and it was realized from the band structure results that all these halides display semiconducting natures with indirect band gaps. The semiconducting natures of Na2MgSiZ6 (Z = I, Br, Cl) halides were further confirmed by their TDOS results. The optimized values of the lattice constants were found to be 11.70 Å, 10.4 Å, and 10.22 Å for Na2MgSiI6, Na2MgSiBr6, and Na2MgSiCl6, respectively. Moreover, the largest volume was observed for the Na2MgSiI6 compound, while the smallest volume was recorded for the Na2MgSiCl6 compound. Na2MgSiCl6 compound exhibited brittle nature, whereas Na2MgSiBr6 and Na2MgSiI6 were found to be ductile. All three materials demonstrated attractive values of optical conductivities, making them befitting candidates for solar cells, LEDs, detectors, and various other optoelectronic devices. From the achieved negative values of formation energy for all the Na2MgSiZ6 (Z = I, Br, Cl) halides, it was comprehended that these compounds could be synthesized practically.

Investigation of a new group of low band-gap semiconducting double perovskite K2MgSnZ6 (Z = Cl, Br, & I) materials and their structural, electronic, mechanical, and optical behaviors via DFT study

This study focuses on potassium based double perovskite materials, specifically a series of K2MgSnZ6 (Z = Cl, Br, & I) halide materials. For the investigated materials, all primary calculations were performed using the Full-Potential Linearized Augmented Plane-Wave (FP-LAPW) method, supported by density functional theory (DFT), and implemented in the WIEN2k code. The Gold-Schmidt tolerance factor values confirm the structural stability of the compounds, while the negative values of formation energy indicate the feasibility of experimental synthesis of the studied materials. The lattice constants were observed to increase as the halide element at the ‘Z’ position was replaced by one with a larger ionic radius. The recorded band-gap values were 2.60 eV, 2.00 eV, and 1.37 eV for K2MgSnCl6, K2MgSnBr6, and K2MgSnI6, respectively. After calculating the elastic constants for all K2MgSnZ6 (Z = Cl, Br, & I) materials, it was found that they satisfy the primary conditions for Born stability required for cubic-phase materials: (1) C11 > B > C12, (2) C11 + 2C12 > 0, (3) C11 > 0, (4) C44 > 0, and (5) C11–C12 > 0. The optical parameters of the K2MgSnZ6 (Z = Cl, Br, & I) double perovskite materials suggest that these materials could play a significant role in practical applications such as solar cells, UV detectors, and various optoelectronic devices.

Pressure-driven perfection: Advancing lead-free halide perovskites Rb2AgBiX6 (X = Br, Cl) for optoelectronic applications

This research employs first-principles simulations to systematically study the structural, elastic, electronic mechanical, and optical characteristics of lead free halide Rb2AgBiX6 (X = Br, Cl) perovskites under pressure. The computed structural parameters are in good agreement with previous experimental and theoretical results. The obtained elastic constants met the Born stability requirements, showing that our materials are mechanically stable at variable hydrostatic pressures, as supported by the computed negative formation energy values. The covalent bond exhibits metallic characteristics, and induced hydrostatic pressure leads to a decrease in bond lengths. Mechanical analysis demonstrates that the studied materials are ductile and mechanically stable, with enhanced ductility under pressure. The materials are small band gap (1.30 eV, 1.801 eV for Rb2AgBiX6 (X = Br, Cl, respectively) semiconductors at ambient pressure with superior optoelectronic performance. Under hydrostatic pressure, Rb2AgBiX6 (X = Br, Cl) experiences a reduction in its band gap (0.545 eV, 1.305 eV for Rb2AgBiX6 (X = Br, Cl, respectively), accompanied by improved physical characteristics. This suggests the potential for increased utilization of this material in optoelectronic devices and solar cells compared to ambient pressure conditions.

Electronic, optical, and thermoelectric efficiency of novel Li-based ternary chalcogenides: First-principles study

The distinguishing features of Li-based ternary chalcogenides are their high thermal stability and adjustable optical characteristics. The presentcomputational investigations focused on the complex interactions between the optical, thermal, and electronic properties of novel LiSmX2 (X = S, Se) ternary chalcogenides. The calculated formation energy and cohesive energy values confirm the stability of these materials. The phonon dispersion results confirm their thermodynamic stability. The predicted spin-polarized band structure calculation signifies an indirect energy gap in both materials. The negative trend in the ε1(ω), indicates that the response of these materials is more analogous to a metal within the given energy range. The intense peaks in the reflectivity spectra suggest that these materials can be employed as filter against UV radiations. Electronic band structures of LiSmS2 and LiSmSe2 may further improve the noticed linear rise in the thermal conductivity that helps electrons transmit heat more efficiently. Our present study may open the door to deeper investigations into these semiconductors’ optoelectronic and thermoelectric characteristics andpotential use in optoelectronic and thermoelectric devices.

High thermoelectric and opto-electronic properties of Ba3NX3 (X=F, Cl) perovskite: Insights from DFT computation

Researchers are working for discovering smart and efficient materials to cope with energy crises. Amongst them, Perovskite are explored extensively by researchers owing to their role in energy harvesting. In this study, structural, elastic, electronic, optical and thermoelectric properties of halide perovskites Ba3NX3 (X = F, Cl) have been explored by using density functional theory techniques. The permissible values of tolerance factor and formation energy ensure the structural and thermodynamic stability of these compounds. Band structure calculations revealed that both materials have semiconducting nature, with the band gap of ∼2.1 eV and 1.9 eV for Ba3NF3 and Ba3NCl3 respectively. The elastic constants suggest both compounds are mechanically stable and exhibit ductile nature. Optical response is studied in the energy range of 0–40 eV of photons. The absorption peaks are observed from 2 eV to 25 eV. Furthermore, it is observed that the relaxation time for Ba3NF3 is longer than Ba3NCl3. Thermoelectric properties such as Seebeck coefficient, electrical conductivity electronic thermal conductivity and figure of merit (ZT) are obtained using BoltzTrap2 code. It is observed that for both materials Seebeck coefficient has almost same maximum value of 1.54 × 10−3 V/K at 300K. The ZT values are found to be 1.23 for Ba3NF3 while 0.9 for Ba3NCl3 at 700K. This work demonstrates that these halides perovskites have a lot of potentiality to prove themselves as best candidates for solar cells and for thermoelectric devices.

(Invited) Phase Engineering for Enhanced Stability of Perovskite Nanowire Optoelectronics

The crystallization of halide perovskites (HPs) into one-dimensional structures has generated considerable research interest for their promising prospects in studying electron transport characteristics and multifunctional nanoscale devices. Various strategies have been developed to achieve in-plane growth of one-dimensional (1D) structures, including epitaxy, capillary-bridge-manipulated graphoepitaxy, and van der Waals epitaxy. Typically, the VLS growth mode, which involves the initial seeding of metallic catalytic nanoparticles to facilitate the process, has realized the out-of-plane and bottom-up synthesis route, opening up a new pathway for the one-dimensional perovskite electronics and optoelectronics.Among many recent advances, Zinc (Zn) has become a significant suppressor of vacancy formation in halide perovskites, establishing its pivotal role in defect engineering for these materials. Herein, we report the Zn-catalyzed vapor-liquid-solid (VLS) route to render black-phase CsPbI3 nanowires operationally stable at room temperature. Based on first-principle calculations, the doped Zn2+ can not only lead to the partial crystal lattice distortion but also reduce the formation energy value from the black phase to the yellow phase, improving the stability of the desired black phase. A series of contrast tests further confirm the stabilization effect of the Zn-doped strategy. Besides, the polarization-sensitive characteristics of black phase CsPbI3 nanowires were revealed. Our work highlights the importance of phase stabilization engineering for CsPbI3 nanowires and their potential applications in anisotropic optoelectronics.

First-Principles study of the electronic Structure, Optical, and thermoelectric properties of novel WSeX (X=S, Te) Chalcogenides: For energy harvesting application

Excellent thermal stability and tunable optoelectronic features are twouniquecharacteristicsof ternary chalcogenides. The first −principles investigations were carried out to look into the intricate interactions between the optical, thermoelectric, and electronicfeatures of novel ternary chalcogenides. The stability of these studied materials was confirmed by the computed formation energy values. There is a strong correlation between the formation energy and the ionicity of W-X bonds, indicating that materials with lower formation energy are connected to a higher number of ionic bonds. The valence band maximum and conduction band minimum of both WSeS and WSeTe materials are located at the Γ-point, which confirms they are direct band gap semiconductors. The heavier element Te is incorporated, making the electronicstructure of WSeTe more complex than that of WSeS. The ε1(ω) was negative at higher photon energy, which is associated with these materials’ response being closer to that of a metallic in the specified energy range. WSeS and WSeTe exhibit peaks in ε2(ω) representing the highest densities of electronic states that can take part in optical transitions. As fewer states become accessible for the high-energy transitions that make these materials ideal for use in optoelectronics and photovoltaics, as confirmed by the n(ω) decreases as a result of a drop in absorption. The behavior of charge carriers and their interactions with the lattices leads to an almost linear increase in electrical thermal conductivity with temperature. Because electron–phonon scattering, the main type of scattering, increases with temperature, electrical conductivity in these materials often decreases as temperature rises.

DFT study of optoelectronic and thermoelectric properties of pure and doped double perovskite Cs2SnI6 for solar cell applications

The global need of energy is raising day by day. To meet this demand double perovskites (DPs) can play a vital role for energy conversion devices. In this letter, we formulated and examined lead-free defect perovskites using a combination of tellurium and tin, denoted as Cs2Sn1-xTexI6 (0, 0.25), utilizing density functional theory which include structural, optical and thermal behavior. Both the optimized volume and lattice parameter exhibit a linear increase with the Te content in Cs2Sn1-xTexI6 (CsSnTeI). The negative value of formation energy for both pure and doped materials along with their Poisson and Pugh ratio confirm the stability of these materials. The band structure analysis reveals its semiconducting behavior, with the band gap expanding proportionally to the increased Te concentration with band gap value of pure (1.20 eV) and doped 91.43 eV) double perovskites. Optical characteristics, including the dielectric function and absorption coefficient, were also analyzed. To expose their potential use of Cs2Sn1-xTexI6 (0, 0.25) in thermoelectric devices, temperature dependent thermoelectric features are investigated reveal that suitability of these materials for energy conversion purposes.

Probing the Structural, Electronic, Thermodynamic, Optical, and thermoelectric features of Lead-Free double perovskites Na2ScAgZ6 (Z=Br, I) for green energy harvesting

In this study,weemployed density-functional theory (DFT) to investigate the structural, electrical, thermodynamic, optical, and thermoelectric characteristics ofNa2ScAgZ6 (Z=Br, I). The Goldschmidt tolerance factor (τ), formation energy, and Gibbs free energy values reveal a high level of thermodynamic and structural stability. Additionally, the thermodynamic stability of the explored double perovskites Na2ScAgZ6 (Z=Br, I) has been verified by employing ab initio finite temperature molecular dynamicssimulation. An indirect bandgap of 2.01 eV (Na2ScAgBr6)and 0.95 eV (Na2ScAgI6)is found using TB-mBJ approximation. This is an essential parameterfor photovoltaic applications. The bandgap values of thesecompounds show that they absorb the majority of radiation in the visible region; thereby substituting bromide withiodidecauses a decrease inthe bandgap. The current investigation aims to study the absorption of light energy, polarization, refractive index, and energyloss across the energy rangesfrom 0 to 6 eV. The dielectric constant has been looked at to identify the highest absorption of incident light in the visible area. The optical characteristics are suitable for use in photovoltaic appliances as the absorption takes place in the visible range. Using the BoltzTraP code, the thermoelectric properties are evaluated and found that the highest ZT values are 0.78 (Na2ScAgBr6)and 0.92 (Na2ScAgI6), respectively. This indicates that these materials can be viable alternatives for photovoltaic and thermoelectric devices.

Investigating Structural, Mechanical, Electronic and Magnetic Properties of Spin-Gapless Quaternary Heusler Alloy Crmnval

Utilizing density functional theory (DFT), the study thoroughly investigates the equiatomic quaternary Heusler compound CrMnVAl, revealing its promising properties across multiple domains. The energy minimization curve shows its structural stability with lattice parameter 5.91Å in ferromagnetic phase. The negative values of formation and cohesive energy indicate its chemical stability, while electronic structure analysis demonstrates spin gapless semiconducting behavior. The total spin magnetic moment of this compound is almost 3.00 μB obeying the Slater-Pauling 18 electron rule (Mt = Zt – 18). The 100% spin polarisation and the Curie temperature higher than ambient temperature indicate that this compound acts as a promising material for spin dependent applications. Furthermore, exploring its mechanical properties complements these findings, offering insights into its structural integrity and suitability for diverse applications. Overall, the study underscores CrMnVAl's potential as a versatile material for spintronics and beyond.

Enhancement of the magneto-electronic properties by GGA and TB-mBJ approaches for KMgO3 perovskite oxide

We investigate the structural, elastic, electronic and magnetic properties of KMgO3. First-principal calculations, based on the formalism of the density functional theory (DFT) and the method of full potential augmented and linearized plane waves (FP-LAPW) implemented in the Wien2k code. The exchange and correlation effects were treated by the following two approximations: generalized gradient approximation (GGA) and Tran-Blaha modified beck Johnson (TB-mBJ) potentials. After analyzing the obtained structural parameters, the results revealed that KMgO3compound is most stable in its ferromagnetic configuration. The formation energy value showed that this compound can be experimentally synthesized. Furthermore, the calculated band structures, and density of states (DOSs) indicate the half-metallic behavior of KMgO3. We found also that the total magnetic moment is an integer value of 3μBwhich confirms the half-metallic character. The magnetic moment specially issues from the spin-polarization of p electrons of O atoms.

Band gap shifting of halide perovskite KSrCl3 from ultra-violet to visible region under pressure for photovoltaic applications

This research delves into the influence of hydrostatic pressure on the structural, electronic, and optical characteristics of the cubic halide perovskite KSrCl3. The reduction in interatomic distance caused by pressure has a considerable effect on the unit cell volume and lattice constant of this perovskite. As pressure increases, the electronic band gap closes, transferring from the ultraviolet to the visible spectrum. This phenomenon increases the efficiency of optoelectronic devices by simplifying the transition of electrons from the valence band to the conduction band. In addition, the material becomes more appropriate for use in a variety of optoelectronic applications when the band gap changes from indirect to direct at pressures of about 50 GPa. A comprehensive optical analysis suggests that KSrCl3 holds potential applications in surgical tools, integrated circuits, QLED, OLED, solar cells, waveguides, and materials designed for solar heat reduction. The tolerance factor “t" confirms the stability of the KSrCl3 phase across the applied pressure range, and the formation energy values with negative values show the attained thermodynamic stability.

Pressure effect on the structural, electronic, elastic, thermodynamic and optical properties of LiZnZ (Z = N, P, and As) Li-based half-Heusler

ABSTRACT Using first-principle calculations based on the density functional theory, we investigated the pressure effect on the structural, electrical, elastic, thermodynamic,electronic and optical properties of Li-based half-Heusler compounds LiZnZ (Z = N, P, and As). We found that the most stable structural phase is the α-phase at 0 GPa for all studied compounds. The obtained lattice parameters at 0 GPa align with existing experimental and theoretical findings for all compounds. The negative values of cohesive and formation energies of LiZnZ indicate that the studied compounds are chemically stable. Band structure calculations confirm the semiconductor behavior of all studied compounds. The calculated elastic and thermodynamic properties show that these compounds are mechanically and thermodynamically stable. The reflectivity values, which are approximately 39%, 54%, and 57% for LiZnN, LiZnP, and LiZnAs, respectively, suggest that the semiconductors LiZnZ are well-suited for optoelectronic applications.

Effect of Ni-doping on the structural and electronic properties of metal halide perovskite CsSnBr3: a DFT study

The structural and electronic properties of pure and Ni-doped perovskite CsSnBr3 in unit cell and supercell were computed using density functional theory at ambient pressure. Computed formation energy values of undoped and Ni-doped CsSnBr3 compounds show that these structures are stable. We used both standard DFT and HSE06 calculation in electronic band structure of pure and Ni-doped CsSnBr3 compounds. Since the band gap of undoped and Ni-doped CsSnBr3 compounds is located at the R symmetry point in the Brilloun zone, these compounds are materials with a direct band gap. In the HSE06 calculation, it was found that the band gap of 12.5% Ni doped-CsSnBr3 increased significantly from 1.1162 eV to 1.4343 eV. The electron charge density, Bader charge analysis and density of states reveal a strong covalent bond between Sn-Br (Ni-Br) and a strong ionic bond between Cs-Br. The direct electronic band gaps of undoped and Ni-doped CsSnBr3 perovskites in the visible energy range show that these compounds can be used effectively in optical applications.

A spin-polarized DFT analysis of the physical attributes of vacancy ordered Rb2TcCl6 double perovskite for optoelectronic and spintronics

Due to their versatile properties, vacancy-ordered double perovskites offer a wide range of potential uses due to their versatile properties. We have thoroughly examined the physical characteristics of vacancy-ordered Rb2TcCl6 in its cubic phase by employing the spin-polarized computations. The ground state energy and optimum structural parameters are obtained in order to assess the structural stability, which is further validated using the tolerance factor and formation energy values. The ductile character of Rb2TcCl6 is revealed by a comprehensive evaluation of mechanical properties. Vickers hardness factor suggests that Rb2TcCl6 can withstand against pressure-induced disturbance more strongly. A direct bandgap for spin-up is measured up to 2.33 eV, while for spin-dn it is 2.02 eV. According to the magnetic moments of 2.69 μB, Rb2TcCl6 is an attractive material for spintronic devices. A number of optical parameters are determined. For optoelectronic applications, Rb2TcCl6 is an excellent choice due to its strong polarization in the visible and ultraviolet regions, as shown by its optical characteristics.

Pressure influenced electronic phase transition, mechanical, optoelectronic, and transport characteristics of double perovskite Rb2AgSbCl6: A first-principles investigation

In this work, we used density functional theory (DFT) simulations to investigate the structural, elastic, electronic, optical, and transport characteristics of pressure-induced Rb2AgSbCl6. By calculating the octahedral and the tolerance factors, the phase stability has been verified. The calculated formation energy and Gibbs free energy values have demonstrated the thermodynamic stability of the material. The outcomes of the mechanical behavior analysis revealed that the pressure-driven Rb2AgSbCl6 is mechanically stable and sustains ductility as well as anisotropy. Additionally, as the pressure is increased from 0 GPa to 100 GPa, the band gap has been reduced from 2.64 eV to 0 eV. The hydrostatic pressure of 100 GPa was the critical pressure at which the material revealed a metallic nature. The optical properties such as absorbance and optical conductivity shift towards lower energy and comparatively higher at increased pressure with minimal energy loss. The thermoelectric characteristics are examined utilizing the BoltzTraP code at different pressures. The figure of merit (ZT) value was increased from 0.76 to 0.80 with the increase in pressure at room temperature. These characteristics render pressure-influenced Rb2AgSbCl6 favorable candidates for utilization in solar cells as well as thermoelectric devices.

Tuning the potentials of aluminum phosphide nanotube photocatalyst for wastewater treatment through band gap engineering: a DFT study

The photocatalytic properties of semiconductor materials, which are controllable through the design of the bandgap structure, make them a promising catalyst for wastewater treatment. This work investigated the photocatalytic properties of single-walled aluminum phosphide nanotube (SWAlPNT) doped with different concentrations of boron (B) atoms for wastewater treatment. Analysis of the structural, electronic and optical properties of the SWAlPNT photocatalyst was performed using the density functional theory approach in terms of plane wave basis set and pseudopotential. SWAlPNT was found to be stable to B doping with 3.6% and 7.1% concentrations. The obtained formation energy values of 12.33 eV, 12.00 eV and 11.98 eV and also cohesive energies of −0.82, eV, −0.75 eV and 0.79 eV for pristine, 3.6% and 7.1% B-doped SWAlPNTs, revealed the systems’ well mechanical and thermodynamic stabilities. Results also revealed that cohesive energy decreases with an increase in concentration of B dopant, which significantly enhances efficient thermal stability. Electronic band gap calculations revealed that pristine SWAlPNT demonstrated a direct band gap value of 0.2 eV. Due to B doping, an indirect band gap value of 1.4 eV was obtained with 3.6% B-doped SWAlPNT, which agreed well with band gaps of other photocatalysts used for wastewater purification. Analysis using optical absorption spectra revealed that 3.6% B-doped system absorbs visible light while 7.1% doped system absorbs both visible and ultraviolet light. This study found both 3.6% and 7.1% B-doped SWAlPNT as suitable photocatalysts for wastewater treatment under solar irradiation, with the 3.6% B-doped system demonstrating relatively better performance for wastewater treatment.

Imidazolium Dicyanomethylides as N‐Ylide Precursors of Anionic N‐Heterocyclic Carbenes

AbstractIn the past, the use of nitrogen ylides focused primarily on cycloadditions, where the 1,3‐dipole was used as a building block for the formation of heterocycles such as pyrroles or pyrrolinones. In this work, we present a new perspective on imidazolium dicyanomethylides with their synthesis and utilization as anionic N‐heterocyclic carbenes (NHCs). The values of relative carbene formation energies (CREF) for a wide range of substituted imidazolium ylides unknown in the literature showed promising properties. In situ trapping reactions of these anionic NHCs with selenium led to anionic, water‐soluble compounds that exhibited remarkable coordination behavior according to X‐ray structure analyses. In addition, the 77Se shifts of the investigated compounds were measured to draw conclusions about their π‐acceptance.

Semiconducting Characteristic of Antiferromagnetic Al4X3Mn (X = P, As and Sb) Compounds with Ab Initio Simulation Methods

This research reports the electronic characteristics of ternary aluminium-based Al4X3Mn (X=P, As and Sb) compounds for the most stable magnetic order which is A-type antiferromagnetic. The related systems are comforming 215 space number with P-43m space group which is simple cubic crystal structure. The computations in this research have been done within the framework of Density Functional Theory. The calculations utilized Perdew-Burke-Ernzerhof type correlation functionals within the meta-generalized gradient approximation. For considered four different type magnetic orders, the visualized volume-energy plots and the calculated formation energy values imply that the magnetic nature of these compositions is A-type antiferromagnetic. Besides, the investigated electronic natures in the detected stable magnetic phase of these systems are semiconductor since the band gaps were observed in their electronic band structures and density of states (Eg = 0.36 eV for Al4P3Mn, Eg = 0.33 eV for Al4As3Mn, and Eg = 0.18 eV for Al4Sb3Mn).