Calculated Density Of States Research Articles

Structural modulation of Na4Fe3(PO4)2P2O7 via cation engineering towards high-rate and long-cycling sodium-ion batteries

Mixed iron-based phosphate Na4Fe3(PO4)2P2O7/C (NFPP) has gradually emerged as a promising cathode material for sodium-ion batteries (SIBs) owing to its affordability and convenient preparation. However, poor electrical conductivity and inadequate sodium-ion diffusion limit the exertion of its electrochemical properties. Herein, a structural modulation strategy based on Cd doping is applied to NFPP to address the above limitations. In situ X-ray diffraction analysis reveals that Cd-doped NFPP (NFCPP) undergoes an incomplete solid-solution reaction driven by Fe2+/Fe3+ redox. Cd doping effectively stabilises the crystal structure, resulting in a minimal 1 % change in unit cell volume during cycling. Density of state calculations indicate that Cd doping reduces the band gap, increases the local electron density and significantly improves electron conductivity. Benefitting from the enhanced electrochemical kinetics and intercalation pseudocapacitance, the optimised Na4Fe2.91Cd0.09(PO4)2P2O7/C (NFCPP@3%) exhibits exceptional rate performance (capacity of 62 mAh/g at 20 C) and ultra-long cycling life (82.7 % after 6000 cycles at 20 C). A full SIB prepared using NFCPP@3% and hard carbon, display a 91 % capacity retention rate at a current density of 130 mA g−1 over 200 cycles. This work demonstrates that doping can effectively enhance electrochemical performance and offers insights into future development of SIBs.

Study of the physical properties of the half-heusler XBrH with (X= sr, Ca and mg) compounds

Half-Heusler alloys are among the most promising thermoelectric materials for medium- and high-temperature waste heat recovery applications. This study investigates the physical properties of Half-Heusler compounds XBrH, with X = Sr, Ca, and Mg. We explored the structural, electronic, optical, and thermoelectric properties of these compounds using density functional theory (DFT) as implemented in the Wien2k package. The Generalized Gradient Approximation (GGA) as proposed by Perdew-Burke-Ernzerhof (PBE) and the modified Becke-Johnson (mBJ) functional were employed to calculate the exchange-correlation interactions. After doing structural optimization for a range of parameters, we discovered that the SrBrH compound is more stable than the CaBrH and MgBrH compounds. Our results show that the density of state calculations indicate semiconductor behavior for the XBrH with (X = Sr, Ca, and Mg) compounds. We also evaluated the real and imaginary parts of the dielectric tensor, the refractive index, the absorption coefficient, the electron energy loss, and the real and imaginary components of the optical conductivity, among other optical parameters. Additionally, we investigated the figure of merit (ZT), electronic and lattice thermal conductivity, Seebeck coefficient, and electrical conductivity. The MgBrH, CaBrH and SrBrH compounds showed p-type behavior, with positive values for the Seebeck coefficient and the greatest value of ≈180 μV/K, according to the thermoelectric data. At 1000 K, the ZT reach their highest values for CaBrH, SrBrH, and MgBrH, respectively, at 2.9, 2.8, and 0.9. The physical properties of the XBrH with (X = Sr, Ca, and Mg) compounds have been studied in detail.

Computational study of LiAlSi, LiAlGe and LiGaSi Half-Heusler alloys for opto-electronic applications

In this comprehensive investigation, the structural, elastic, electronic, optical, thermodynamic and thermoelectric properties of Lithium-based ternary semiconductors, namely LiAlGe, LiAlSi, and LiGaSi were explored. Utilizing first-principle calculations, various material properties were accurately determined . The lattice constants, bulk modulus, and equilibrium total energies were obtained revealing that the three alloys are mechanically stable and show brittle behavior. Electronic band structures and density of states calculations, employing PBE+U, unveiled band gaps of 1.32 eV, 1.55 eV, and 1.47 eV for LiAlGe, LiAlSi, and LiGaSi, respectively, suggesting their suitability for photovoltaic applications. Analysis of the absorption spectra allowed the identification of the active window of the electromagnetic spectrum for these materials. Subsequently, the materials exhibited desirable optical properties, characterized by efficient optical absorption, with the highest peaks in the visible light and ultraviolet regions of the electromagnetic spectrum, low reflectivity, and a high dielectric constant. These collective findings indicate the potential of these materials for application in the field of opto-electronics. Furthermore, calculations of thermoelectric properties disclosed figure of merit values of 0.830, 1.046, and 0.697 at 950 K for the LiGaSi, LiAlSi, and LiAlGe HH alloys, respectively, further highlighting their potential for use in thermoelectric applications.

Analysis of the nonlinear optical properties, vibrational spectra, DFT method and photovoltaic performance of cyanidin-3-rutinoside chloride

This study aims to identify a cyanidin-3-rutinoside chloride that exhibits both photovoltaic performance and nonlinear optical properties, which may be utilized in the field of optoelectronics. Prior to investigating these properties, the stable structure must be determined. For this purpose, its conformational analysis is performed by the Molecular Force Field method with the spartan program. The exact nature of the stable configuration has been ascertained by empirical evidence. The energy of the stable configuration is -1654184.76 kcal/mol, and its dipole moment is 9.94 Debye. Cyanidin-3-rutinoside chloride has been investigated using experimental FT-IR and Raman spectroscopies. Meanwhile, the DFT method at the B3LYP/6-311 + + G(d, p) level was employed in order to study the simulated FT-IR and Raman spectra, the HOMO-LUMO analysis, the molecular electrostatic potentials (MEP), and the non-linear optical (NLO) characteristics of the title molecule. The HOMO and LUMO energies are − 6.45 and − 3.64 electron volts (eV), respectively, with a gap value of 2.81 eV. Additionally, the title compound’s open-circuit voltage, the transition density matrix light-harvesting efficiency, driving force, and binding energy were calculated with by taking photovoltaic cell properties into account. Furthermore, investigations of hole reorganization energy, electron reorganization energy, and total reorganization energy were carried out at the B3LYP/6-31G(d, p) level for the cyanidin-3-rutinoside chloride of interest. In addition, density of state calculations and NBO were made at the B3LYP/6-31G(d, p) level. We calculated the following values for LHE, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{V}_{oc}$$\\end{document}, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{{\\Delta\\:}\ ext{G}}_{\ ext{i}\ ext{n}\ ext{j}\ ext{e}\ ext{c}\ ext{t}}$$\\end{document}, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{E}_{b}$$\\end{document}, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\\lambda\\:}_{h}$$\\end{document}, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\\lambda\\:}_{e}$$\\end{document} and \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{\\lambda\\:}_{total}$$\\end{document} : 0.06, 2.45 eV, 0.20 eV, 0.56 eV, 0.50 eV, 0.57 eV and 1.06 eV, respectively.

Synthesis of Zintl Phase Metal Silicide Thermoelectric Materials in Magnesium/Zinc Flux.

Zintl phases have potential applications as thermoelectric materials for power generation and cooling owing to their complex crystal structures and unique electronic properties. We carried out reactions of silicon with barium and strontium in excess Mg/Zn flux to synthesize (Ba/Sr)5+xMg19-xSi12 Zintl phases, investigating the effect of varying Ba/Sr ratio on site mixing and thermoelectric properties. (Ba/Sr)5+xMg19-xSi12 compounds with 0 < x < 3 are charge-balanced Zintl phases which adopt the hexagonal Ho5Ni19P12 structure type (space group P6̅2m). Density of states calculations indicate that these materials are semimetals. Single-crystal X-ray diffraction data and elemental analysis for Ba5Mg19Si12, Ba4.86Sr2.94Mg16.20Si12, Ba3.63Sr4.20Mg16.17Si12, Ba1.93Sr5.99Mg16.08Si12, and Sr7.82Mg16.18Si12 show occupation of barium and strontium cations in Ho sites, while strontium mixes with magnesium on a specific Ni site. Powder XRD data of products show that they are single phase throughout the sample. Thermoelectric measurements indicate that increasing strontium content and mixing on three cation sites decreases thermal conductivity; it is hypothesized that improved overall thermoelectric behavior is likely due to the rattling of the Sr cations in their positions.

Enhanced figure of merit in two-dimensional ZrNiSn nanosheets for thermoelectric applications

A novel two-dimensional (2D) half-Heusler ZrNiSn nanosheet for thermoelectric applications was designed from bulk half-Heusler ZrNiSn through first-principles calculation. Investigation of bulk half-Heusler and 2D nanosheet ZrNiSn was performed with the Quantum Espresso code based on a density functional theory plane wave basis set. Electronic band structure and density of states calculations were used to study the confinement effects. On moving from bulk to 2D a change of structure is observed from face-centered cubic to trigonal due to confinement effects. The semiconducting nature of bulk ZrNiSn is undisturbed while moving to a 2D nanosheet; however, the band gap is widened from 0.46 to 1.3 eV due to the restricted motion of electrons in one direction. Compared with bulk ZrNiSn, 2D nanosheets were found to have a higher Seebeck coefficient a lower thermal conductivity and higher figure of merit, which makes 2D ZrNiSn nanosheets suitable for thermoelectric applications. Atomically thin 2D structures with a flat surface have the potential to form van der Waals heterojunctions, paving the way for device fabrication at the nanoscale level.

Unveiling the geometrical and mechanical properties of Σ3 (111) grain boundaries in Ni-based alloys: From interfacial insights

Understanding the properties of interfaces and grain boundaries is pivotal for advancing the design and performance of modern materials and devices. The mechanical strength and durability of materials are significantly influenced by the integrity of these interfaces and grain boundaries. In this study, we employ density functional theory calculations to investigate the geometries, electronic properties, and mechanical behaviors of Σ3 (111) grain boundaries in Ni, AlNi3, and FeNi3 systems. Result reveals that these grain boundaries exhibit trigonal, hexagonal, and hexagonal close-packed structures with minimal bond length distortions, attributed to specific misorientation angles of 60°. They also demonstrate bonding characteristics akin to their corresponding polycrystalline bulk materials, indicating stability and twist character with anti-phase boundaries. Evaluation of grain boundary energetics indicates low energy values and stability across the studied systems. Furthermore, we conduct a detailed examination of the interfacial grain boundary structures of Σ3 (111) Ni/AlNi3 and Σ3 (111) Ni/FeNi3, revealing trigonal closed space configurations with twist character and anti-phase boundaries. Electron localization in interfacial regions suggests a metallic nature of interfacial bonds, supported by density of state calculations and positive Cauchy pressure. Assessment of mechanical properties indicate ductile behavior due to structural heterogeneity, moderate anisotropy. Overall, present study underscores the enhanced mechanical properties resulting from heterogeneity, offering promise for future applications in advanced materials and devices. Additionally, a comparative analysis with highlights the advancements and contributions of this study to the existing body of knowledge.

Ternary Complexes of BiI3/CuI and SbI3/CuI with Tetrahydrothiophene.

Reactions of BiI3/CuI mixtures with tetrahydrothiophene (THT) in toluene produce 2-D sheet networks BiCu3I6(THT)n (n = 2, 3, or 4), depending on reaction conditions. All three structures are based on BiI6 octahedra, which share pairs of (μ2-I)2 with Cu3(THT)n units. BiCu3I6(THT)2 features Cu2(μ2-I)2 rhombs with close Cu···Cu interactions and is accompanied by formation of the very complex HBi3Cu12I22(THT)8. Reactions of SbI3/CuI with THT in toluene produced a SbCu3I6(THT)2 network shows Cu3(μ2-THT)2 units, like its Bi congener, but Cu6(μ2-I)6 barrels rather than rhombs. Isolated SbI3 units are stacked above the Cu6I6 barrels. A molecular compound, Sb3Cu3I12(THT)6 consists of a face-sharing Sb3I12 stack, in which the Cu-THT units are bonded in asymmetric fashion about the central SbI6. Metal-halide bonds were investigated via QTAIM and NLMO analyses, demonstrating that these bonds are largely ionic and occur between the Bi/Sb and I p orbitals. Hirshfeld analysis shows significant H···H and H···I interactions. Diffuse reflectance spectroscopy (DRS) reveals band edges for the Bi species of 1.71-1.82 eV, while those for the neutral Sb complexes are in the range of 1.94-2.06 eV. Mapping of the electronic structure via density of state calculations indicates population of antibonding Bi/Sb-I orbitals in the excited state.

Prediction of magnetic properties of 3d transition-metal adsorbed InS monolayers

Based on the first principles, we have investigated the electronic structures and magnetic properties of monolayer InS adsorbed 3d transition metal (Co, Cr, Cu, Fe, Mn, Sc, Ti, V, Zn), The results show that all 3d transition metal adsorptions are relatively stable, except Ti atoms, with adsorption energies ranging from −0.36 eV to −3.82 eV. The results of band structure calculations show that the InS monolayers adsorbed by Co, Cr, Fe, Mn, Sc, and V produce spin splitting and generate magnetic moments of different sizes, among them, the InS system adsorbed by Cr generates the largest magnetic moment of 5.28 μB. The band structure and the density of states calculations indicate that the TM atoms have a strong interaction with the InS surface. We also calculated the magnetic anisotropy energies of the Co, Cr, Fe, Mn, Sc, and V adsorption systems, and the results show that the MAE magnitudes of these adsorption systems range from −0.679546 meV/f.u. to 0.279594 meV/f.u., which displays PMA/IMA properties. Our results demonstrate the good potential of monolayer InS with adsorbed 3d transition metal for spintronics device applications.

Experimental and DFT investigations of Al-doped ZnO nanostructured thin films

Al doped ZnO thin films at different concentrations have been successfully synthesized, characterized experimentally, and investigated theoretically by density functional theory (DFT). The crystal structure analysis was carried out using X-ray diffraction (XRD) data. Wurtzite structures of a single phase with a preferred orientation along the (002) plane are obtained. The surface morphology has been investigated by atomic force microscopy (AFM) which showed homogeneous and compact surfaces with spherical shape grains that change to a wave like nematic structure with increasing Al doping rate. For a complete characterization, experimental and theoretical analysis of optical and electrical properties have been done using UV–Vis spectrophotometry, the four-probe method, electronic band structure and density of states calculations, and the Boltz-Trap code based on the semi classical theory of Boltzmann. Both, experimental and theoretical, studies indicate an increase in gap energy with high transparency in the visible region and electrical conductivity improvement due to a non-localized state around the Fermi level. The experimental and theoretical studies agree well and show a similar tendency of the results. Therefore, these properties of Al-doped ZnO open a new avenue for optoelectronic and photonic device applications.

Zigzag boron nitride nanotube functionalization as a sensor for the recognition of group IIA (Mg2+, Ca2+) metal ions, quasi-metal (Si2+, Ge2+) ions, and transition metal (Cu2+, Zn2+) ions: a computational study.

Boron nitride nanotubes (BNNTs) provide an exceptional and sophisticated platform for detecting metal ions with high surface area and remarkable chemical stability. Metal cations tend to bind to the surface of BNNTs, which leads to significant changes in the electrical properties of nanotubes. BNNT-based metal ion sensors have shown promising results in various applications, including water quality monitoring, biomedical research, industrial quality control, and environmental monitoring. In the present study, we have explored the electronic sensitivity of the BNNT to metal ions (Si2+, Ge2+, Cu2+, Zn2+, Mg2+, and Ca2+). The interaction between the ions with the pristine BNNT is performed in the solution phase. The results show that ion adsorption on the nanotube surface is exothermic and favorable. The density of states calculation is presented to investigate the electronic properties of the nanotube during the adsorption process. The results display that an increase in the electrical conductivity of the complexes accompanies the reduction in the energy gap. Based on the obtained data, the Si2+ and Ge2+ cations adsorbed on the BNNT with satisfactory Eg changes (%ΔE) can be promising candidates for better sensing ability. All calculations are conducted within the density functional theory (DFT) using the ωB97XD functional and 6-31G(d,p) basis set. The present approach incorporates the utilization of empirical atom-atom dispersion in conjunction with long-range correction. The calculations are performed using the quantum chemistry package GAMESS, and the obtained results are visualized by employing the GaussView 6.0.16 program.

Depicted simulation model for removal of second-generation antipsychotic drugs adsorbed on Zn-MOF: adsorption locator assessment.

Electronic durable behavior on the material surface was accompanied by a class of antipsychotic drugs (APD) to describe the surface modification in the designed adsorption model. Hierarchically Zn-MOF system was utilized for estimating its capacity for drug molecule removal. Geometrically optimized strategy on the studied systems was performed using DFT/GGA/PBE. FMOs analysis was depicted based on the same level of calculations, and molecular electrostatic potential surface (MEP) was generated for unadsorbed and adsorbed systems to illustrate the variation in the surface-active sites. By interpreting the electronic density of states (DOS), the atomic orbital can be identified as a major or minor electronic distribution by PDOS graph. Adsorption locating behavior was considered to detect the significant surface interaction mode between APD and Zn-MOF surface based on lower adsorption energy. The stability of the adsorbed model was best described through dynamic simulation analysis with time through elevated temperatures. The non-covalent interactions were described using RDG/NCI analysis to show the major favorable surface interaction predicting the highly stable adsorption system. The most accurate geometrical computations were performed using the materials studio software followed by surface cleavage and vacuum slab generation. The first principle of DFT was used to apply CASTEP module with GGA/PBE method for band structure and DOS calculations. Three systems of antipsychotic drugs were computationally studied using CASTEP simulation package and adsorbed on an optimized Zn-MOF surface. Adsorption locator module predicted the preferred adsorption mechanistic models, in which the first model was arranged to be more stable, to confirm the occurrence of some interactions in the adsorption mechanism.

Activation of carbon dioxide on zinc oxide surfaces doped with cerium

AbstractThe adsorption of carbon dioxide on the surfaces of zinc oxide doped with cerium was studied. For this, a theoretical study was carried out using computational simulations based on density functional theory to determine possible improvements in photocatalytic activity. for the capture and dissociation of carbon dioxide. Calculations were performed using density functional theory within the Perdew-Burke-Ernzerhof generalized gradient approximation, also the Hubbard correction together with ultrasmooth atomic pseudopotentials and a basic plane wave implemented in the Quantum-ESPRESSO package. The doping concentration level considered in this work was 6.25%, among the results, the semiconducting character of zinc oxide was evident from the density of states calculations, it was also found that by adding cerium impurities to zinc oxide, the values of the lengths and angles of the bonds vary a little, this may be due to the small difference in covalent radius that the zinc atom has with respect to the cerium atom, consequently, changes occurred in the electronic properties that consist in intermediate states in the energy bandgap located around the Fermi energy. This may suggest that the cerium-doped zinc oxide system can probably absorb visible light, which could lead to possible improvements in the photocatalytic properties of the material. Furthermore, we found that by adding carbon dioxide to the cerium-doped zinc oxide surface, the carbon dioxide is activated and this could suggest the dissociation or reduction of this contaminant.

Electronic Structure Analysis of the A10 Tt2 P6 System (A=Li-Cs; Tt=Si, Ge, Sn) and Synthesis of the Direct Band Gap Semiconductor K10 Sn2 P6.

Investigating the relationship between atomic and electronic structures is a powerful tool to screen the wide variety of Zintl phases for interesting (opto-)electronic properties. To get an insight in such relations, the A10 Tt2 P6 system (A=Li-Cs; Tt=Si-Sn) was picked as model system to analyse the influence of structural motives, combination of elements and their properties on type and width of the band gaps. Those compounds comprise two interesting structural motives of their anions, which are either monomeric trigonal planar TtP3 5- units which are isostructural to CO3 2- or [Tt2 P6 ]10- dimers which correspond to two edge-sharing TtP4 tetrahedra. The A10 Tt2 P6 compounds were structurally optimized for both polymorphs and subsequent frequency analysis, band structure as well as density of states calculations were performed. The Gibbs free energies were compared to determine temperature dependent stability, where Na10 Si2 P6 , Na10 Ge2 P6 and K10 Sn2 P6 were found to be candidates for a high temperature phase transition between the two polymorphs. Additionally, the unknown, but predicted compound K10 Sn2 P6 was synthesized and characterized by single crystal and powder x-ray diffraction. It crystalizes in the monoclinic space group P 21 /n and incorporates [Sn2 P6 ]10- edge sharing double tetrahedra. It was determined to be a direct band gap semiconductor with a band gap of 2.57 eV.

High‐performance diffusion model for inverse design of high Tc superconductors with effective doping and accurate stoichiometry

AbstractThe pursuit of designing superconductors with high Tc has been a long‐standing endeavor. However, the widespread incorporation of doping in high Tc superconductors significantly impacts electronic structure, intricately influencing Tc. The complex interplay between the structural composition and material performance presents a formidable challenge in superconductor design. Based on a novel generative model, diffusion model, and doping adaptive representation: three‐channel matrix, we have designed a high Tc superconductors inverse design model called Supercon‐Diffusion. It has achieved remarkable success in accurately generating chemical formulas for doped high Tc superconductors. Supercon‐Diffusion is capable of generating superconductors that exhibit high Tc and excels at identifying the optimal doping ratios that yield the peak Tc. The doping effectiveness (55%) and electrical neutrality (55%) of the generated doped superconductors exceed those of traditional GAN models by more than tenfold. Density of state calculations on the structures further confirm the validity of the generated superconductors. Additionally, we have proposed 200 potential high Tc superconductors that have not been documented yet. This groundbreaking contribution effectively reduces the search space for high Tc superconductors. Moreover, it successfully establishes a bridge between the interrelated aspects of composition, structure, and property in superconductors, providing a novel solution for designing other doped materials.image

Mg/MgO interfaces as efficient hydrogen evolution cathodes causing accelerated corrosion of additive manufactured Mg alloys: A DFT analysis

The corrosion rates of additive-manufactured Mg alloys are higher than their as-cast counterparts, possibly due to increased kinetics for the hydrogen evolution reaction on secondary phases, which may include oxide inclusions. Scanning Kelvin Probe Force Microscopy demonstrated that MgO inclusions could act as cathodes for Mg corrosion, but their low conductivity likely precludes this. However, the density of state calculations through density functional theory using hybrid HSE06 functional revealed overlapping electronic states at the Mg/MgO interface, which facilitates electron transfers and participates in redox reactions. Subsequent determination of the hydrogen absorption energy at the Mg/MgO interface reveals it to be an excellent catalytic site, with HER being found to be a factor of 23x more efficient at the interface than on metallic Mg. The results not only support the plausibility of the Mg/MgO interface being an effective cathode to the adjacent anodic Mg matrix during corrosion but also contribute to the understanding of the enhanced cathodic activities observed during the anodic dissolution of magnesium.

Ab initio study of stability and quadrupole coupling constants in borophosphates.

The DFT method was used to predict the formation energies and quadrupole coupling constants CQ in a series of borophosphates: Li3BP2O8, Li2NaBP2O8, Na3BP2O8, Li2B3PO8, Na5B2P3O13, LiNa2B5P2O14 and Na3B6PO13 composed of different networks and different amounts of borate and phosphate units. The change in formation energies with increasing number of B atoms in this series is attributed to the multiplicity of boron sites and is explained by density of states calculations. The calculated CQ values of 7Li, 23Na and 11B are correlated with the coordination and distortion of polyhedra to elucidate the influence of local and more distant environments. As for the CQ of 11B, it should be in the ranges of 0.26-0.36, 0.48-0.84 and ∼1 MHz for boron tetrahedral distortion indices of 0.004-0.013, 0.015-0.019 and 0.033, respectively, whereas CQ ∼3.0 MHz corresponds to boron in a triangular site. The obtained numerical relationships make it possible to predict the quadrupole frequencies for these nuclei based only on their local environment, and vice versa, to propose structural models from NMR data. These results provide guidance for studying similar characteristics of other borophosphates, the structure of which varies depending on the initial reaction, composition and temperature.

Synthesis and study of rare earth(Dy3+) doped CoCr2O4 ceramics for supercapacitor applications

Rare earth doped Cobalt Chromates are exhibits a significant interest among other materials for supercapacitors Applications. In the present work we reported Dysprosium(Dy3+) doped Cobalt Chromate(CoCr2O4) for possible application in supercapacitors. Samples were prepared by solution combustion method with the general formula CoCr2-xDyxO4 (where x = 0, 0.01, 0.03, and 0.05) using glucose and urea as fuels. As prepared samples were characterized by using “X-ray diffractometer”(XRD), “Transmission electron microscopy”(TEM), and “field emission scanning electron microscopy(FESEM) techniques to study the analytical and morphological structure of the CoCr2-xDyxO4. For the first time, the electrochemical fabrication of CoCr2-xDyxO4 were reported. Using “cyclic voltammetry”(CV), “galvanostatic charge–discharge’(GCD), electrochemical impedance spectroscopy (EIS), and cyclic stability testing, the electrochemical capabilities of CoCr2-xDyxO4 were explored in great detail. The behavior of capacitance was evaluated utilizing CV at a variety of scan speeds, GCD at a selection of constant current densities, and EIS at a selection of frequencies. CV and GCD data for tested electrodes showed their capacitive behavior. The calculated capacitance was 0.29–0.38 F cm−2. It is found increasing with Dy3+ concentration. Based on CV testing results at a scan rate of 1 mV s−1. At a current density of 3 mA cm2, the obtained capacitance was 0.21, 0.22 and 0.23 F cm−2 respectively. The analysis of the compared Nyquist plots of complex impedance revealed that the actual part of the impedance dropped as the Dy3+ content increased. This pointed to an increase in conductivity, which was advantageous for the storage of charge, as also supported by density of states calculations, which demonstrated the remarkable distribution of density of states across the fermi level after Dy3+ doping in CoCr2O4, indicating improved electronic features of CoCr2-xDyxO4.

First-principles calculations to investigate elastic, electronic, optical, and thermodynamic properties of intermetallic elements Pt3T (T = Nb, Ru, Rh, Pd, and Ag)

Different significant properties as example structural stability, stiffness constants, hardness, machinable index, band structure, interatomic bonding, optical, as well as thermal behavior of a few transitional intermetallic elements Pt3T (T = Nb, Ru, Rh, Pd, and Ag) are accompanied by ab-initio-based DFT simulation through CASTEP code. The reliability of this work has been established through the comparison of similar research-based previous work. The structural properties show a consistent relationship with the previously investigated theoretical and experimentally evident data. Investigating through the insightful elastic parameters, mechanical stabilities for all phases have been confirmed. All intermetallic phases studied in this paper show metallic nature, as confirmed by band structure and density of state calculations. In all cases, outstanding results of high bulk and plastic deformation resistance, high hardness, high melting point, and high thermal conductivity have been observed for the Pt3Ru compound. It is found (from electronic measurements) that the unique hybridization between Pt and Ru plays a key role in obtaining the better performance of Pt3Ru compound. The high bulk modulus, Young's modulus, and hardness value revealed the strong interatomic bond formation in Pt3Ru phase as well as harder type of material than others. Apart from Pt3Ru, the compounds Pt3T (T = Nb, Rh, Pd, and Ag) contain high machinability index as they have low hardness which ensured that these phases have potential applications in industry. The high melting point temperature and other excellent properties obtained for Pt3Ru compound comprise its superiority for high-temperature sector industrial applications. On the other hand, the lower minimum thermal conductivity for Pt3Pd and Pt3Ag ensured their potential applicability as TBC materials. However, all phases exhibited exceptional reflectance properties over long range photon energy, even in the UV region, which shows the applicability of these compounds to use as solar reflector materials.

Enhancement of dielectric properties and conduction mechanism in BaTi0.85Sn0.15O3 for energy storage application

To achieve cost effective materials with improved dielectric properties, BaTiO3 and BaTi0.85Sn0.15O3 have been prepared by solid state reaction technique introducing a two step sintering method. The structure of the samples has been investigated by X-Ray diffraction (XRD) and Raman spectra at room temperature (RT ~ 300 K). In addition, crystallographic microstructures and grain morphology have been evaluated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) respectively. Apart this, the band structure along with density of states (DOS) are evaluated using first principle calculations for BaTiO3 and BaTi0.85Sn0.15O3. The band structure depicts bandgap of 1.80 eV and 1.82 eV for BaTiO3 and BaTi0.85Sn0.15O3 respectively. The DOS calculation displays the increase in hybridization of Ba2+ (A site) and Ti4+ (B site) cations with oxygen octahedra resulting in off-center displacement of cations in Sn doped BaTiO3 sample. A disordered cubic phase is obtained in BaTi0.85Sn0.15O3 sample sintered at 1350 °C resulting in the highest dielectric constant εr′ with a minimum loss tanδ. The conduction mechanism has been analyzed from the temperature and frequency dependence of resistivity ρ. The overall forecasts indicate BaTi0.85Sn0.15O3 annealed at 1350 °C to be a potential candidate for energy storage capacitive devices in the electronic industry.