Cambridge Serial Total Energy Package Research Articles

First principle investigation of tungsten based cubic oxide perovskite materials for superconducting applications: A DFT study

Perovskite will play an important role in the materials study to investigate the different properties. The CASTEP (Cambridge Serial Total Energy Package) code will be used to investigate the material properties. The structural, electronic, thermodynamic, and optical characteristics of novel tungsten-based oxide-perovskite materials WXO3 (where X = Cr and Hg) were investigated by using first principle calculations (CASTEP) with ultra-soft pseudo-potential PW (plane wave) and GGA (generalized gradient approaches)-PBE (Perdew-Burke-Ernzerhof) exchange correlation-functional. According to the calculations, both compounds have a space group of PM3m with a cubic structure. The results we discovered are entirely novel compounds, as demonstrated by computations. According to calculations, the band structure of WXO3 has a zero band gap. The graphical interpretations like DOS (density-of-states), partial DOS, and band structure in both perovskite materials reveal conclusive proof of conductive behavior. The presence of ionic bonds is revealed by a study of bonding characteristics shown by Poisson's ratios of 0.71 and 0.49 for WCrO3 and WHgO3, respectively. The WCrO3 and WHgO3 optical characteristics have also been studied and assessed. The Fermi level will be so highly overlapped that most of the electrons will lie from the conducting valence band VB to the conduction band CB and vice versa. Thermodynamic characteristics are studied, like Debye temperature, sound velocity, melting temperature, and compressibility. These compounds are extensively used in medical devices, sensitive devices, computer parts, and storage systems. Further investigation will be required on these materials with doping any element to enhance the band gap to study the other properties like photocatalytic and solar cell applications.

First-principles calculations to investigate structural, elastic, thermodynamic, electronic, and optical properties of AgXCl3 (X = Fe, Co & Mn)

To enable the development of better-integrated devices, a large number of perovskite compounds with a variety of attributes can be developed while keeping their structural identity. We conducted our research to examine the structural, electrical, and optical characteristics of AgXCl3 (X = Fe, Co, and Mn) compounds. The AgXCl3 perovskite structure was improved through the use of DFT simulations that were implemented within the Cambridge Serial Total Energy (CASTEP) package. Because the value of the tolerance factor does not fit the circumstance, the AgCoCl3 structure is not a perfect perovskite structure. Structures made of AgCoCl3 and AgMnCl3 are ductile whereas AgFeCl3 structure is brittle. Electronic properties are observed using HSE06 functional. While both the AgCoCl3 and AgMnCl3 structures exhibit half-metallicity, the AgFeCl3 structure shows metallicity. The conductivity and absorption coefficients for both constructions peak in the ultra-violet range and decrease as the energy level increases.

Theoretical benchmark of structure, optical, and transport mechanism of Sm-doped double perovskite cobaltite

Double perovskite cobaltites have attracted more fascination because of their tunable functionality in optoelectronic and electronic devices. In this study, we used the Cambridge Serial Total Energy Package code under equilibrium circumstances, to examine the structural, and optical properties of Bi2Ca2-xSmxCoO6 (x = 0.00, 0.05, and 0.10). In this work, the studied samples have been prepared by co-precipitation method. X-Ray Diffraction reveals a monoclinic structure. Jonscher’s power law was employed to investigate the conduction mechanism in the synthesized samples. Nyquist plots were studied for the investigation of electrical transport properties. The maximum electrical conductivity for the Sm-doped sample was 98.3 S-cm−1.

Lead-free novel perovskite Ba3AsI3: First-principles insights into its electrical, optical, and mechanical properties

Lead-free halide perovskites are a crucial family of materials in the fabrication of solar cells. At present, Solar cells are facing several challenges such as mechanical and thermodynamic instability, toxicity, unsuitable optical parameters, bandgap, and absorption coefficient. Ba3AsI3 is a halide perovskite which has demonstrated good efficiency and tremendous promise for usage in solar cell applications, and it offers a possible solution to these issues. In this study, the properties of the Ba3AsI3 perovskite solar cell were investigated using first-principles density functional theory (FP-DFT) calculations with the CASTEP (Cambridge serial total energy package) formulation. Most of its physical qualities, including its elasticity, electrical composition, bonding, optoelectronic characteristics, and optical characteristics have not yet been explored. In this work, these unexplored properties have been thoroughly investigated using density functional theory-based computations. The Born-Huang criterion and phonon dispersion characteristics have revealed that the material is mechanically stable. The bonding nature has been investigated using the density of states curves, Mulliken population analysis, and electronic charge density. Additionally, different elastic parameters demonstrate that Ba3AsI3 has reasonably high machinability and is mechanically isotropic. ELATE's three-dimensional visualization and optical properties also show isotropic behavior in all directions. The band structure shows that the bandgap is direct. Based on its direct bandgap, stability, large range of absorption coefficient, and suitable optical parameters, Ba3AsI3 is recommended as an absorber layer for solar cell fabrication in a near future.

Non‐Toxic and Stable Double Perovskite Solar Cells Based on Cs2AgSbX6 Light Harvester: First Principle Calculations‐Aided Theoretical Estimation

AbstractOwing to the low long‐term stability and high toxicity, high‐efficiency perovskite solar cells are yet to be commercialized. Therefore, it is imperative to find a reliable and environmentally benign alternative perovskite light harvester. Herein, the study presents a non‐toxic double perovskite light harvester based on Cs2AgSbX6 (where X = Cl, Br, and I) as a substitute, which can render both high efficiency and long‐term durability. The optoelectronic properties of the Cs2AgSbX6 double perovskite light harvesters are investigated with the Cambridge Serial Total Energy Package (CASTEP) software package that is committed to density functional theory (DFT). The bandgap (indirect) tunability of Cs2AgSbX6 double perovskite light harvesters and associated changes in the density of states (DOS) are explored. The obtained results are further loaded as input to the SCAPS‐1D software package to assess the potential of Cs2AgSbX6 double perovskite solar cells. With the FTO/AZnO/Cs2AgSbX6/MoO3/rear contact device structure, the thickness and bulk defect density of the Cs2AgSbX6 light harvester have superior control over the performance of the double perovskite solar cells. The highest theoretical efficiency of ≈29.9% is estimated for the Cs2AgSbI6 light harvester. Additionally, the effectiveness of several prospective back electrodes is examined.

Exploration of the structural, optoelectronic, magnetic, elastic, vibrational, and thermodynamic properties of molybdenum-based chalcogenides A2MoSe4 (A =Li, K) for photovoltaics and spintronics applications: a first-principle study.

In the present work, the cubic phase of the chalcogenide materials, i.e., A2MoSe4 (A =Li, K) is examined to explore the structural, optoelectronic, magnetic, mechanical, vibrational, and thermodynamic properties. The lattice parameters for Li2MoSe4 are found to be a= 7.62 Å with lattice angles of α=β=γ=90° whereas for K2MoSe4, a= 8.43 Å, and α=β=γ=90°. These materials are categorized as semiconductors because Li2MoSe4 and K2MoSe4 exhibit direct energy band gap worth 1.32 eV and 1.61 eV, respectively through HSE06 functional. The optical analysis has declared them efficient materials for optoelectronic applications because both materials are found to be effective absorbers of ultraviolet radiations. These materials are noticed to be brittle while possessing anisotropic behavior for various mechanical applications. The vibrational properties are explored to check the thermal stability of the materials. On the basis of thermodynamics and heat capacity response, Li2MoSe4 is more stable than K2MoSe4. The results of our study lay the groundwork for future research on the physical characteristics of ternary transition metal chalcogenides (TMC). These physical properties are explored for the first time while using a first-principles approach based on density functional theory (DFT) in the framework of Cambridge Serial Total Energy Package (CASTEP) by Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) functional. However, GGA+U and HSE06 are also employed to improve electronic properties. Kramers-Kronig relations are used to evaluate the dielectric function with a smearing value of 0.5 eV. Voigt-Reuss-Hill approximation is used for seeking the elastic response of these materials. The thermodynamic response is sought by harmonic approximation. The density functional perturbation theory (DFPT) approach is used for investigating atomic vibrations.

First-principles and experimental study of structural, electronic, and enhanced dielectric response in Bi2Ca1.95Sm0.05CoO6 nanoparticles

In this study, we synthesized Bi2Ca1.95Sm0.05CoO6 (BCSCO) by the Co-precipitation route. X-ray diffraction was used for structural analysis, which confirmed the monoclinic structure with space group P21/m. Here, we employ the CASTEP (Cambridge Serial Total Energy Package) approach, we conducted a theoretical investigation of the structure, electronic, and optical properties of BCSCO double perovskites. FTIR spectra, BCSCO presents three absorption bands that correspond to the Bi(Ca)-O, O-Co-O, and Co-O. The morphological study showing the agglomeration phenomenon has occurred in the synthesized sample. The AC conductivity and dielectric response have also been studied as a function of frequency (100 Hz-3 MHz) at different temperatures (100 °C-600 °C). Temperature-dependent dielectric relaxation was investigated, and employing the non-linear Debye fitting to determine the spreading factor and relaxation time. The maximum value of the dielectric constant is 2.4 × 106 at 600 °C. AC conductivity is examined at (100 °C-600 °C) using Jonscher’s power law. The model fitting shows the Overlapping Large Polaron Tunneling conduction mechanism for BCSCO. In order to explore the impact of grain barriers and interior, the Nyquist plot was utilized, and the results are inter-connected.

A first-principles study to investigate the physical properties of Sn-based hydride perovskites XSnH3 (X = K, Li) for hydrogen storage application

Based on density functional theory, the present study used the Cambridge serial total energy package code to figure out the structural, electronic, magnetic, optical, and mechanical properties of perovskite hydrides XSnH3 (X = K, Li). The band gap, total density of states, and partial density of states of the hydrides under consideration have been calculated, confirming the metallic behavior via the overlapping of the conduction and valence bands with a zero-band gap. The XSnH3 lattice parameters, determined using generalized gradient approximations, are 4.3 Å for KSnH3 and 4.1 Å for LiSnH3. Both of these materials are found to be hard, antiferromagnetic, and anisotropic in nature. The Poisson's ratio indicates that LiSnH3 is brittle while KSnH3 is ductile. The B/G ratio also confirms the brittleness of LiSnH3 and the ductility of KSnH3. The hydrogen storage capacity of KSnH3 and LiSnH3 is calculated to be 1.88 wt % and 2.35 wt %. Both materials have the potential to store hydrogen, as evidenced by the storage properties, but it is determined that LiSnH3 is the superior material to utilize for use in applications involving hydrogen storage.

AB-INITIO STUDY OF STRUCTURAL, ELECTRONIC AND MAGNETIC PROPERTIES OF RbFeO3AND CsFeO3 MATERIALS

A density functional theory DFT was applied to calculate structural, electronic and magneticproperties of Alkali iron perovskites. Gradient generalized approximations GGA-PBE and GGA-WCwithin DFT were implemented in CASTEP code (Cambridge Serial Total Energy Package) to conductour calculations. Ultra-soft plane wave pseudo-potentials were used to solve Cohen-Sham equations. Forthe two materials RbFeO3 and CsFeO3, we found cubic and ferromagnetic ground states. Results indicatealso lattice parameters between 3,80A° and 3,96A° and magnetic moments between 4,45 µB and 4,57µB.Band structures showed that both materials were conductors. This work prospect that the two compoundscandidate to utilize in spintronics technology.

STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF BaSnA3 (A=S or Se); A DFT study

Chalcogenide perovskites play an important role in the solar cell photovoltaic applications. A lot of researches in the present decade studied these materials, such as optical and photo-electric properties. Herein we are applied first principles density functional theory (DFT) to study the structural, electronic and optical properties of BaSnS3 and BaSnSe3 compounds. Gradient generalized approximations GGA-PBE and GGA-WC from the DFT was implemented in CASTEP (Cambridge Serial Total Energy Package) and usedin our calculations. Results indicated that both BaSnS3 and BaSnSe3 crystallize in the orthorhombic structure and have a semi-conductivity behavior with energy gap between 0,35 eV and 0,97 eV. This paper prospects more works in the perovskites based-Sn.

Determination of Band Structure and Compton profiles for Aluminum-Arsenide Using Density Functional Theory

First-principles computations of the electrical characteristics of AlAs have been carried out using the density functional theory-DFT and the Local Density Approximation-LDA,methods (DFT) and Generalized Gradient Approximation-GGA. We utilized the CASTEP's plane wave basis set implementation for the total energy computation (originally from Cambridge Serial Total Energy Package). We used to look at the AlAs structure's structural parameter. The band gap was overestimated by the Generalized Gradient Approximation and LDA techniques, although the band gap predicted by the GGA is more in line with the experimental finding, according to the electronic structure calculation utilizing the two approximations. A semiconductor with a straight band-gap of 2.5 eV is revealed by the GGA calculation. The energy band diagram is used to calculate the total and partial densities of AlAs states. Multiple configurations of the ionic model were calculated. of Al+xAs−x (0.0 ≤ x ≤ 1) are also performed utilizing free-atom profiles. According to the ionic model, 0.75 electrons would be transferred from the valence 5p state of aluminum to the 3p state of Arsenide.

Theoretical description of structural, electronic, elastic, mechanical, and optical response of Ba1−xCdxTiO3 for optoelectronic applications

Barium titanate is well-known oxide-based perovskite with numerous potential applications in optoelectronic and energy storage devices. This manuscript aims to present an ab initio study to correlate effect of changes observed in electronic properties with structural, elastic, mechanical, optical and thermodynamic properties as well as acoustic behavior of Cd decorated barium titanate for optoelectronic applications. Cadmium (Cd) inclusion with varying concentrations (x = 0, 0.11, 0.33, 0.55, 0.77, 1) at Barium site was taken into consideration for a systematic study for the tunable character of material. For DFT study, Cambridge Serial Total Energy Package (CASTEP) under generalized gradient approximation was used. Cd substitution at Ba site has turned out to be effective for fine band gap tuning of barium titanate. The band gap gradually decreases except x = 0.11 and make new end material a conductor. Thus provide a way to design a device for optoelectronic application using a tunable band gap mechanism. To investigate the effect of band gap reduction as well as changes observed in other physical quantities, total and partial densities of states along with elemental density of states were computed. It is evident from the results that Cd surely introduces new states in pristine BaTiO3 (BTO), the main cause of electronic change. The question of stability of material was also addressed using extracted mechanical properties from calculated elastic constants and instituted concentrations separately to satisfyBorn’s stability criteria.Parameters based on Debye temperature and wave velocity calculations were also extracted to investigate thermodynamic and acoustic behavior of system.Optical response was evaluated and presented comparatively. Refractive index and static dielectric function increase to 3.24 and 10.50 respectively with gradual inclusion of Cd concentration. It is evident that the presented materials are not only lead-free for environment-friendly energy storage applications but also a promising candidate for solar cell applications because of ideal band gap range. Moreover, improved optical behavior of these materials is claimed to stand out for optoelectronic applications as well as thermoelectric properties.

Structural, electronic, magnetic, and optical properties of MFe2O4 (M = Ni, Fe, Co) spinel ferrites: A density functional theory study

AbstractThe structural, electronic, magnetic, and optical properties of MFe2O4 (M = Ni, Fe, Co) ferrites were investigated by employing Cambridge Serial Total Energy Package code using density functional theory. LDA+U was used to investigate the structural, electronic, magnetic, and optical properties of MFe2O4 (M = Ni, Fe, Co) ferrites at different pressures 0, 5, 10, 15, and 20 GPa. The simulated X‐ray diffraction (XRD) pattern of MFe2O4 (M = Ni, Fe, Co) ferrites was investigated and the computed lattice parameters decreased 8.62–8.32, 8.68–8.35, and 8.567–8.267 Å at 0–20 GPa, respectively. XRD revealed that the unit cell's volumes (640.50–575.93, 653.97–582.182, 627.22–563.550), X‐ray densities (4.86–5.40, 4.70–5.28, 3.97–4.43), and interatomic distance (2.6099–2.5180, 2.6221–2.4260, 2.5831–2.4928) of MFe2O4 (M = Ni, Fe, Co) ferrites were also decreased with the increasing pressure 0–20 GPa, respectively. The LDA+U calculations predicted that the NiFe2O4, Fe3O4, and CoFe2O4 ferrite followed the properties of a semiconductor exhibiting a direct band gap of 1.2, 1.13, and 0.710 eV at 0 GPa which were decreased to 0.846, 0.710, and 0.461 eV at 20 GPa, respectively. The computed density of states revealed that MFe2O4 (M = Ni, Fe, Co) ferrites exhibited good spin polarization behavior, and Ni–O, Fe–O, and Co–O bonds were covalent. The Mullikens investigated the ted decrease in bong length of MFe2O4 (M = Ni, Fe, Co) ferrites versus 0–20 GPa as well as according to Hirschfeld analysis the magnetic moment (3.348–3.335, 4.12–4.10, 3.737–3.735) and saturation magnetization (79.06–78.7, 99.33–98.9, 88.93–88.352) of MFe2O4 (M = Ni, Fe, Co) ferrites were decreased with increased pressure 0–20 GPa, respectively. The reflectivity and absorption specialize in visible and ultraviolet regions showing their stability for optoelectronics, photocatalysis, and solar cell applications.

Comparative study of the structural, mechanical, electronic, optical and thermodynamic properties of superconducting disilicide YT2Si2 (T=Co, Ni, Ru, Rh, Pd, Ir) by DFT simulation

DFT simulation-based ab-initio approach has been executed for examining the relative physical properties of superconducting disilicide materials YT2Si2 (T = Co, Ni, Ru, Rh, Pd, Ir). This is the first comparative theoretical investigation of these materials, which is done through Cambridge Serial Total Energy Package module. Extremely good relation has been observed between the synthesized and calculated structural parameters of all the superconductors. Mechanical structural stability of all the phases has been confirmed from the investigated elastic stiffness parameter. The phonon dispersion curve indicates that the YT2Si2 compounds with T = Co, Ni, Ru, and Ir are dynamically stable, but those with T = Rh and Pd are dynamically unstable. The investigated elastic moduli show good agreement with previously calculated data where available. Also, the fundamental polycrystalline features such as bulk modulus, shear modulus, Young's modulus, Pugh's and Poison's ratios, ductile/brittle nature and hardness of superconducting YT2Si2 (T = Co, Ni, Ru, Rh, Pd, Ir) have been examined. Ductile nature of YRh2Si2, YPd2Si2 and brittle nature of YCo2Si2, YNi2Si2, and YIr2Si2 have been observed from analyzing of polycrystalline elastic parameters where YRu2Si2 lies on the border line of ductile/brittle nature. The high bulk modulus, Young's modulus, and hardness of YIr2Si2 ensured that this phase has high ability to resist volume and plastic deformation and suitable in industrial applications. On the other hand, the small Young's modulus of YPd2Si2 ensured its application as a thermal barrier coating (TBC) material. Metallic nature of YT2Si2 (T = Co, Ni, Ru, Rh, Pd, Ir) has been confirmed from the band structure and DOS calculations. Mulliken atomic populations and charge density map reveal the existing of covalent and ionic bond inYT2Si2 (T = Co, Ni, Ru, Rh, Pd, Ir). Different optical features like dielectric function, refractive index, photo conductivity, reflectivity, absorption and loss function of YT2Si2 (T = Co, Ni, Ru, Rh, Pd, Ir) have been executed through CASTEP code directly. The elevated reflectivity in the UV energy site of these phases ensured their application as good solar reflector in this energy site. Furthermore, the thermodynamic properties of superconducting YT2Si2 (T = Co, Ni, Ru, Rh, Pd, Ir) have been determined from the elastic stiffness constants. The high conductivity of YCo2Si2 is ensured from its high Debye and melting temperature. The minimum thermal conductivity of YPd2Si2 ensured that it is suitable to use as a thermal barrier coating (TBC) material.

First-principles calculations to investigate structural, electronic, elastic and optical properties of radium based cubic fluoro-perovskite materials

Perovskite materials play a vital role in the field of material science via experimental as well as theoretical calculations. Radium semiconductor materials are considered the backbone of medical fields. These materials are considered in high technological fields to be used as controlling the decay ability. In this study, radium-based cubic fluoro-perovskite XRaF3 (where X = Rb and Na) are calculated using a DFT (density functional theory). These compounds are cubic nature with 221 space groups that construct on CASTEP (Cambridge-serial-total-energy-package) software with ultra-soft PPPW (pseudo-potential plane-wave) and GGA (Generalized-Gradient-approximation)-PBE (Perdew-Burke-Ernzerhof) exchange-correlation functional. The structural, optical, electronic, and mechanical properties of the compounds are calculated. According to the structural properties, NaRaF3 and RbRaF3 have a direct bandgap with 3.10eV and 4.187eV of NaRaF3 and RbRaF3, respectively. Total density of states (DOS) and partial density of states (PDOS) provide confirmation to the degree of electrons localized in distinct bands. NaRaF3 material is semiconductors and RbRaF3 is insulator, according to electronic results. The imaginary element dispersion of the dielectric function reveals its wide variety of energy transparency. In both compounds, the optical transitions are examined by fitting the damping ratio for the notional dielectric function scaling to the appropriate peaks. The absorption and the conductivity of NaRaF3 compound is better than the RbRaF3 compound which make it suitable for the solar cell applications increasing the efficiency and work function. We observed that both compounds are mechanically stable with cubic structure. The criteria for the mechanical stability of compounds are also met by the estimated elastic results. These compounds have potential application in field of solar cell and medical. ObjectivesThe band gap, absorption and the conductivity are necessary conditions for potential applications. Here, literature was reviewed to check computational translational insight into the relationships between absorption and conductivity for solar cell and medical applications of novel RbRaF3 and NaRaF3 compounds.

Advanced Modeling and Simulation Methods for Evaluation of Thermal Neutron Scattering Materials

With the rise of interest in thermal neutron scattering data for advanced reactor, criticality safety, and shielding applications, new experimental data are required for evaluation of new materials or for re-evaluation (or validations) of previously evaluated materials. New experimental data are evaluated in a three-step process: (1) computing the phonon characteristics, (2) computing the dynamic structure factor (DSF) from the data, and (3) using the experimental setup to simulate the experimental data. All three steps have challenges, ranging from the need for a suffciently general material simulation code—a processing code that can compute the corresponding DSF—to having a detailed layout of the instrument/beamline/facility where the data were measured. Whereas phonon characteristics of materials can be computed using various methods (molecular dynamics, density functional theory, etc.), a high-fidelity computation of the DSF and the simulation of the experiment based on the DSF is vital to the accuracy of the evaluation. The latter two steps can be achieved by using the two corresponding code systems developed by instrument scientists at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory: (1) OCLIMAX, a program that calculates the dynamic structure factor from DFT and MD simulation results, and (2) MCViNE, a Monte Carlo neutron ray-tracing program designed to simulate neutron scattering experiments. Recently, polyethylene and yttrium hydride were measured at the Wide Angular-Range Chopper (ARCS) and SEQUOIA instrument stations of the SNS. These experiments are simulated using the density functional theory code, the Cambridge Serial Total Energy Package (CASTEP), to compute its phonon characteristics (eigenvalues/vectors and PDOS), which is then processed using OCLIMAX to yield the DSF, and finally the data at each instrument station are simulated by the MCViNE for comparison to the measured data for evaluation. For comparison to conventional evaluation methods, the scattering data processed from OCLIMAX are compared against those processed from the LEAPR module of NJOY, and the results from MCViNE simulations are compared against previously used simplified beamline models implemented in the Monte Carlo N-Particle (MCNP) code.

First-principles calculations to investigate structural, electronic, optical and mechanical properties of Mg-doped CaMoO3 cubic perovskites for fuel cell applications

The structural, optical, electrical, and mechanical characteristics of pure and Mg-doped CaMoO3 perovskites materials were examined in a first-principle research based on density functional theory. The current study employs the PBE (Perdew Burke-Ernzerhof) exchange co-relational functional of GGA along with the USP (Ultra-soft Pseudo-potential) plan wave and CASTEP (Cambridge Serial Total Energy Package) code (Generalized Gradients Approximation). The impact of Mg on the structural, optical, electrical, and mechanical characteristics of CaMoO3 is examined using a generalized gradient approximation (GGA) and an ultra-soft pseudo-potential. After adding Mg to the Mo site, it is discovered that the band gap of CaMoO3 with Mg doping has significantly decreased. According to the DFT investigation, Mg is an ideal material to lower CaMoO3's band gap. The volume of crystal cells similarly fell from 61.99 to 57.94 A3 with the addition of Mg due to the difference in ionic radii between Mo and Mg. The incorporation of Mg in CaMoO3 results in a highly stable material, which is demonstrated by the as-calculated negative cohesive energy values, according to the as-obtained elastic constants (Cij). The elastic constants, ductility, elastic moduli, and elastic anisotropy of pure and Mg-doped CaMoO3 cubic perovskite materials have also been investigated. These findings demonstrate that Mg doping successfully raises CaMoO3's elastic moduli. The Mg-doped CaMoO3 material transforms from brittle to ductile due to the introduction of Mg at sites of Mo, as computed Pugh's ratio is dropped from 2.499 to 1.995 and Poisson's ratio from 0.323 to 0.285. For both pure and Mg-doped CaMoO3, band topologies, densities of states, and charge density re-locations are also expected.

Modeling the structural, electronic, optoelectronic, thermodynamic, and core-level spectroscopy of X–SnO3 (X=Ag, Cs, Hf) perovskites

Tin-based cubic perovskites have gained increasing scientific interest as an alternative to lead-based perovskite materials in industrial applications of photovoltaic and optoelectronic devices due to their lesser toxicity, affordability, and availability. Thus, using the density functional theory (DFT) approach, the structural, electronic, optoelectronic, thermodynamic, phonon, and X-ray spectroscopic properties of XSnO3 (X = Ag, Cs, Hf) perovskite materials were investigated. For structural, electronic, and optoelectronic property computations, the Quantum Espresso Simulation Package (QESP) with the PBE-GGA functional was used, whereas phonon dispersion, phonon density of states, thermodynamics, and X-ray spectroscopy were computed using the Cambridge Serial Total Energy Package (CASTEP) code. Our calculations revealed that the calculated lattice constant values of XSnO3 (X = Ag, Cs, Hf) increased as the size of the cation X (X = Ag, Cs, Hf) increased. The valence bands were dominated by sn-4d orbital contributions for partial density of states. O-2p electrons, on the other hand, are crucial in the formation of conduction bands. Per the band structure, CsSnO3 has a metallic property with no band gap, HfSnO3 is a semiconductor with a band gap of 3.90 eV, and AgSnO3 is an insulator with a band gap of 4.30 eV. In addition, the dielectric function, extinction coefficient, and refractive index calculations were performed in the energy range of 0–10 eV. Furthermore, for each perovskite studied, we calculated thermodynamic parameters as a function of temperature. We discovered an exponential increase in entropy and a nearly linear pattern of enthalpy increase with temperature. These results show that the XSnO3 (X = Ag, Cs, Hf) materials absorb UV light and may be used to absorb UV rays. But relative to AgSnO3 and HfSnO3 materials, CsSnO3 is a better choice for usage in optoelectronic applications.

Magnetoelectric, and dielectric based switching properties of co-doped BiFeO3 for low energy memory technology: A first-principles study

First-principles calculations are carried out to grow half-metallicity, tune dielectric and magnetoelectric properties of pure and doped bismuth ferrite BiFeO3 (BFO) with lanthanum (La) at A-site and cobalt (Co) at B-site as mono- and co-dopants. These calculations are performed in the Cambridge Serial Total Energy Package (CASTEP) code using ultra-soft pseudopotential (USP). A large band gap has been observed in the pure rhombohedral phase. The Co impurity atom is more favorable to decrease the band gap while La pushes the BFO towards half-metallic behavior, which develops 100% polarization in all doped BFO systems. From the dielectric response of BFO, high spin current density <s> of 8.7 × 103 A/m2 and charge current density (j) of 6.3 × 10–11 A/m2 have been observed in the La doped system. In the case of magnetic properties, the strong magnetization (M) 32.13 MA/cm2 and the large magnetoelectric coupling coefficient of 6.72× 10−6 s/m have been observed in co-doped BFO.

Effect of Various Electron and Hole Transport Layers on the Performance of CsPbI3-Based Perovskite Solar Cells: A Numerical Investigation in DFT, SCAPS-1D, and wxAMPS Frameworks.

CsPbI3 has recently received tremendous attention as a possible absorber of perovskite solar cells (PSCs). However, CsPbI3-based PSCs have yet to achieve the high performance of the hybrid PSCs. In this work, we performed a density functional theory (DFT) study using the Cambridge Serial Total Energy Package (CASTEP) code for the cubic CsPbI3 absorber to compare and evaluate its structural, electronic, and optical properties. The calculated electronic band gap (E g) using the GGA-PBE approach of CASTEP was 1.483 eV for this CsPbI3 absorber. Moreover, the computed density of states (DOS) exhibited the dominant contribution from the Pb-5d orbital, and most charges also accumulated for the Pb atom as seen from the electronic charge density map. Fermi surface calculation showed multiband character, and optical properties were computed to investigate the optical response of CsPbI3. Furthermore, we used IGZO, SnO2, WS2, CeO2, PCBM, TiO2, ZnO, and C60 as the electron transport layers (ETLs) and Cu2O, CuSCN, CuSbS2, Spiro-MeOTAD, V2O5, CBTS, CFTS, P3HT, PEDOT:PSS, NiO, CuO, and CuI as the hole transport layers (HTLs) to identify the best HTL/CsPbI3/ETL combinations using the SCAPS-1D solar cell simulation software. Among 96 device structures, the best-optimized device structure, ITO/TiO2/CsPbI3/CBTS/Au, was identified, which exhibited an efficiency of 17.9%. The effect of the absorber and ETL thickness, series resistance, shunt resistance, and operating temperature was also evaluated for the six best devices along with their corresponding generation rate, recombination rate, capacitance-voltage, current density-voltage, and quantum efficiency characteristics. The obtained results from SCAPS-1D were also compared with wxAMPS simulation results.