Calculated Band Gap Research Articles

Exploring HgO Effect on Structural, Dielectric, Optical, and Radiation Shielding Properties of Borate-based Glass

Abstract Glass samples in the system 60-xB2O3+20BaO+20K2O+xHgO (0≤x≤15 mol.%) were prepared via melt quenching method. Infrared spectroscopy revealed structural modifications with increasing HgO content, characterized by a shift in the BO4/BO3 ratio. Dielectric and impedance spectroscopy studies indicated enhanced ionic conductivity with higher HgO concentrations. Optical properties, including refractive index, extinction coefficient, and optical band gap, were determined. The optical absorption edge exhibited a red shift with increasing HgO, attributed to structural changes. Refractive index measurements showed an anomalous dispersion behavior at shorter wavelengths, followed by normal dispersion at longer wavelengths. Optical band gap calculations indicated a decrease with increasing HgO content, suggesting increased disorder. The mass attenuation coefficient (MAC) and linear attenuation coefficient (LAC) were calculated using the Phy-X/PSD software. Increasing HgO content led to a significant enhancement in both MAC and LAC values, particularly at lower energies. The mean free path (MFP) exhibited a corresponding decrease with higher HgO content. Overall, the results demonstrate the potential of these glasses as effective radiation shielding materials.

First‐Principles Study of Structural and Elastic, Electronic, and Thermoelectric Properties of PdSe2

The thermoelectric material in orthorhombic (Pbca) phase is studied with the help of density functional theory implemented in WIEN2k. The main properties of investigated are elastic, electronic, and thermoelectric properties. The anisotropy factors obtained with the elastic constants indicate that is strongly anisotropic. The Tran and Blaha‐modified Becke–Johnson exchange potential is used for bandgap calculations. The BoltzTraP code is used to find out the thermoelectric properties of . At 300 K, the maximum value of the Seebeck coefficient is 200 μV K−1 for the hole carrier concentration of 2.5 × 1019 cm−3 and is 241 μV K−1 for the electron carrier concentration of 1.2 × 1019 cm−3. The power factor (PF) and figure of merit (ZT) are calculated for different carrier concentrations and temperatures. The optimum value of ZT for bulk PdSe2 as calculated in this work is ≈0.6 for hole carrier concentration (p = 2.6 × 1020 cm−3) at 800 K, which suggests as a potential material in thermoelectric applications at higher temperatures.

Tecoma stans intermediated green synthesis of copper oxide nanoparticles, its characterization, paracetamol degradation and biological activities

The main objective of the present research work is to green synthesize copper oxide nanoparticles (CuO NPs) and to study its potential against various enmities to safeguard our environment and health. Based on this approach, preparation of CuO NPs was accomplished using four different volumes (10, 25, 40, and 50 mL of leaves extract) of Tecoma stansleaves extract. Moreover, all the synthesized CuO NPs were characterized using XRD, UV–visible, FTIR, and SEM with EDS analysis. From the XRD pattern, the structures of all the synthesized CuO NPs were found to be monoclinic in phase. According to the UV–visible studies, the calculated band gap energy values for all the prepared CuO NPs were higher compared to bulk CuO, which was 1.2 eV. Further, the FTIR results showed the presence of CuO bond and SEM with EDS analysis revealed the surface morphology of CuO NPs andthe presence of elements showing the purity of synthesized CuO NPs, respectively. The optimized condition for the preparation of CuO NPs were 50 mL of leaves extract mixed with 50 mL of double distilled water (CuO4 NPs) showed a spheroidal morphology as evident from the HRTEM images. XPS analysis used to find the oxidation state of detected elements especially for copper and oxygen. The predicted BET and Langmuir surface area of CuO4 NPs were calculated to be 40.305 m2/g and 5074.12 m2/g respectively. Photocatalytic degradation of paracetamol (PCM) using CuO4 NPs was investigated, and the effect of parameters such as pH, initial concentration of PCM solution, and catalyst dosage were studied under UV light irradiation. The highest removal of 95.15 % had been achieved at 120 min under optimized reaction conditions. Additionally, CuO4 NPs also exhibited exemplary antibacterial activity against bacillus subtilis bacteria with a zone of inhibition of 26 mm. Further, in vitro cytotoxic behaviour of CuO4 NPs was estimated using A549 cancer cells by MTT assay. Thus, the green synthesis of CuO NPs using Tecoma stans leaves extract has the capacity to participate in photocatalytic and biological activities.

Optimizing photocatalysis: Tuning europium concentration in zinc oxide nanoparticles for superior performance

This work reports, improved photo catalytic performance of ZnO by band gap engineering via Eu doping (0.5–2.0 %). Single phase wurtzite structure of sol gel derived ZnO and Eu (0.5–2.0 %) doped ZnO are confirmed by XRD, FTIR and Raman spectra. Slight variation in structural parameter, FTIR stretching mode at 677 cm−1 and Raman E2 peak position indicate substitution of Eu+3 in ZnO. Calculated band gap decreases [3.05-2.89] with Eu concentration due to generation of charge trap level. Dye degradation of MO improved in Eu doped ZnO as compare to ZnO. The catalytic effectiveness is clearly shown by significant breakdown of a commonly used MO dye (at a concentration of 120 mg l−1). ZnO: Eu 2 % has a remarkable clearance rate of 99.37 %, which is explained by pseudo-first-order kinetics. The increase in oxygen radical ion concentration due to presence of Eu2O3 impurity phase in Eu 2 % doped ZnO supports MO degradation mechanism.

Correlation between structural modifications and physical parameters of Sb doped InSe alloys for optoelectronic applications

Bulk samples of In0.1Se0.9-xSbx (0 ≤ x ≤ 0.24) were synthesized using the conventional melt-quenching technique. The impact of Sb doping on the structural and physical properties of InSe alloys was systematically explored. The substitution of Sb at the expense of Se introduces defects and dislocations in the lattice, which significantly influence the properties of the InSeSb system. With increasing Sb content, physical parameters such as the average coordination number, cross-linking density, mean bond energy, and cohesive energy were observed to increase. Theoretically calculated band gap values lie between 1.7 and 1.3 eV. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of the alloys, revealing the coexistence of rhombohedral α-In2Se3 and orthorhombic Sb2Se3 phases. Energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition, showing the presence of In, Se, and Sb in the bulk samples. Raman and FTIR spectroscopy further validated the presence of distinct structural units and molecular bonds as a function of Sb content, confirming the coexistence of α-In2Se3 and Sb2Se3 phases alongside In–Se, Se–Se, and Sb–Se bonds. A strong correlation was established between the experimental findings and theoretically calculated parameters, including the average coordination number, mean bond energy, glass transition temperature, cohesive energy, and optical band gap. This study provides a comprehensive insight into the compositional dependence of structural and physical properties in InSeSb chalcogenide alloys, enhancing our understanding of their potential applications.

Advancement in the Thermoelectric Performance of Bulk SnSe: GGA+U Approach for Band Gap Calculation and Strain Induced Thermal Conductivity

Advancement in the Thermoelectric Performance of Bulk SnSe: GGA+U Approach for Band Gap Calculation and Strain Induced Thermal Conductivity

Structural, electronic and optical properties of α -Si3N4, β-Si3N4 and γ-Si3N4 using density functional theory

Density Functional Theory (DFT) has in recent years gained a lot of popularity and has become an efficient and reliable tool in the study of material properties. This is specifically due to its computational convenience and excellent results in the prediction of material properties, which is aided by the development of highly efficient and accurate functionals. DFT has successfully been applied in a vast study of material at both ground and excited states. In this study based on DFT structural, optical, electronic properties and phonon frequency of silicon nitrides of different phases were studied using the GGA as exchange-correlation functional. For the electronic band gap calculation the results was obtained using the GGA and the hybrid HSE06 respectively for α -Si3N4 with space group (P31c), β-Si3N4 with space group (P63/m) and γ-Si3N4 phase polymorph with space group (14‾3d). Results obtained for the phases α -Si3N4 shows a narrow indirect band gap while β and γ -Si3N4 indicate a wide indirect band gap material for wide possible application in high temperature and high-power applications. Cohesive energy calculation and phonon frequencies were obtained to check the mechanical and dynamic stability of the three different phases. Results obtain for density of states, partial density of states and the optical properties, such as absorption coefficient, refractive index, extinction coefficient, reflectivity and electron energy loss spectra which all show good agreement with previous studies and relative experimental data.

Heterogeneous visible-light photoredox catalysis with NiCl2@g-C3N4 for induced C(sp2)-H/N[sbnd]H cross-dehydrogenative coupling

A novel photoactive NiCl2@g-C3N4 catalyst system, which effectively drives C(sp2)-H/NH bond formation between quinolin-2(1H)-ones, primary and secondary aliphatic amines under blue light irradiation. The NiCl2@g-C3N4 composite with a NiCl2 loading of 0.7wt% had the highest photoactivity, and the calculated band gap energy value is 2.56 eV The nickel ion could act as an electron acceptor enhancing carrier separation and transfer efficiency, greatly enhanced the photoreaction efficiency of g-C3N4. Preliminary mechanistic studies indicate upon visible light irradiation, the photo-generated electrons and holes act as oxidants, thereby generating amine radicals in the absence of external chemical oxidants. This provides a straightforward and efficient approach for directly 3-aminating quinoxalines-2(1H)-ones. Moreover, the heterogeneous catalyst can be recycled at least six times without significant activity loss.

Exploring the Physical Properties of LiBeX (X = Sb, Bi) Compounds via Ab Initio Approach

In the current study, it is aimed to scrutinize the physical properties of LiBeX (X = Sb, Bi) compounds in detail. Density‐functional‐theory‐based WIEN2k and the Vienna Ab initio Simulation Package, employing the generalized gradient approximation of Perdew–Burke–Ernzerhof, Wu–Cohen, and Tran–Blaha‐modified Becke–Johnson (TB‐mBJ) exchange‐correlation schemes, are utilized to better validate the outcomes. The compounds exhibit energetic, lattice dynamic, and mechanical stability. Electronic structure calculations using the TB‐mBJ functional reveal indirect bandgaps of 1.007 eV for LiBeSb and 0.789 eV for LiBeBi compounds, respectively. The partial charge distribution in the highest occupied molecular orbital and the lowest unoccupied molecular orbital discloses maximum charge localization around the X site. The examination of the crystal orbital Hamilton population reveals the strongest BeX bonding interactions among the bonding pairs. The physio‐mechanical properties indicate brittle and mechanically anisotropic behavior of both compounds, with covalent bonding characteristics. The comparative analysis suggests that the TB‐mBJ potential is suitable for bandgap calculations due to its close alignment with experimental results. Additionally, the optimized results for these compounds indicate their potential for use in optoelectronic devices, such as visible to ultraviolet sensors and photovoltaics. The determined properties are consistent with previous theoretical findings.

The electronic and magnetic properties of Cr-doped ZnO monolayer at higher percentage by first principles calculations

The crystal structure, structural stability, electronic band structures and magnetization of Cr-doped ZnO monolayer (ML) have been investigated by GGA+U method using first principles calculations in this work. The stability of these systems is confirmed by the negative formation energies at different Cr concentrations. The calculated band gaps with and without the Hubbard U correction aligned well with other computational results. With the increase of Cr concentration, the band gap of Cr-doped ZnO monolayer decreases for the spin-up configuration. However, in the spin-down configuration, the band gap increases first and then decreases and the maximum band gap is obtained at 22.22% Cr concentrations. At 33.33% Cr concentration, the ZnO ML exhibits metallic behavior. The density of states (DOS) analysis reveals an asymmetric nature, indicating ferromagnetism in Cr-doped ZnO MLs at various concentrations, with a magnetic moment per Cr atom of approximately 3.99 μB. The total magnetic moment rises with increasing Cr concentration. Charge density difference analysis shows increased magnetization with higher Cr concentration. At 22.22% Cr concentration, the ZnO ML exhibits ferromagnetism and semiconducting properties, suggesting significant potential for spintronic applications as a diluted magnetic semiconductor.

Macroporous material modified efficient silver molybdate composite for effective photocatalytic degradation of dyes

Macroporous banana peel biochar (BBC), silver molybdate (Ag6Mo10O33) and new composite Ag6Mo10O33@BBC were synthesized and characterized. Ag6Mo10O33@BBC was prepared using acid modulator for the first time. The photo degradation efficiency of Ag6Mo10O33@BBC in the degradation of methylene blue (MB) was found to be 95.16 %. The adsorption and degradation properties of the photo catalyst were studied using UV–visible spectroscopic analysis and band gap calculation. The photocatalytic activity favourable properties such as reduced band gap of 2.07 eV and high surface area of 7.28 m2/g of Ag6Mo10O33 was resulted upon compositing it with BBC.

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.

Enhancing dye-sensitized solar cells efficiency through organic dyes-sensitized holmium-doped TiO2/SnO2 nanocomposites blended with P3HT

The pursuit of sustainable energy solutions has spurred innovation in photovoltaic technology, with dye-sensitized solar cells (DSSCs) emerging as promising contenders. This study presents a novel approach leveraging holmium-doped TiO2/SnO2 nanocomposites sensitized with organic dyes, Arsenazo-III, carminic acid, and dithizone, blended with poly (3-hexylthiophene) (P3HT). Through meticulous characterization and analysis, key parameters including short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and overall percent efficiency (%) were scrutinized to evaluate photovoltaic performance comprehensively. Absorption spectra analysis facilitated the calculation of band gaps, revealing a significant reduction from 3.10 eV in pure Titania (TiO2) nanoparticles to 2.72 eV upon doping with Holmium and coupling with SnO2. Notably, Arsenazo-III dye-sensitized holmium-doped TiO2/SnO2 nanocomposites exhibited highest power conversion efficiency, achieving a promising efficiency of 2.10 %, which marked a significant improvement over the reference device (0.82 %). This improvement is attributed to the synergistic effects of holmium dopant incorporation and SnO2 interaction, enhancing light responsiveness. The findings not only validate the efficacy of nanohybrid assemblies but also contribute valuable insights to solar cell technology advancement.

A homochiral Nickel(II) complex [Ni(P'N)2]Cl2: Synthesis, characterization, crystal structure, luminescence, DFT and Hirshfeld surface studies

A new complex ([Ni(P'N)2]Cl2) is synthesized from an anhydrous NiCl2 and a bidentate P'N (S,S)-NH2CHPhCHPhPPh2) ligand with an enantiopure ethylene backbone. The solubility of the complex in methanol aids its crystallization by slow evaporation. A single crystal X-ray diffraction study of the complex reveals a distorted square planar geometry with the phosphinyl groups coordinated in a cis(P,P) configuration. This imposes steric effects that influence the crystal packing of the complex in an orthorhombic unit cell. The complex possesses characteristic metal to ligand charge transfer (MLCT) transition in the UV region with a peak absorption at 294 nm corresponding to 4.22 eV, which correlates with 4.24 eV derived from the DFT calculation of the energy band gap between the highest molecular orbital (HOMO:7.39 eV) and lowest unoccupied molecular orbital (LUMO:3.15 eV) of the complex. With an excitation wavelength of 415 nm (3.00 eV), the complex emits photons with wavelength 488 nm (2.54 eV) in the blue region of the visible spectrum. The circular dichroism spectrum has multiple peaks in the UV region mainly associated with transitions within the chiral array of phenyl groups. The bond lengths, bond angles, and vibrational bands obtained by simulation of the optimized structure of the complex provide analytical details that strongly correlate with the experimental data with adjusted R2 of 0.9826 (bond lengths), 0.9911 (bond angles) and 0.9983 (vibrational bands). The Hirshfeld surface analysis shows that H…H and C…H interactions between phenyl rings of the cations contribute significantly to the crystal packing of the complex.

Green synthesis of copper oxide nanoparticles using solanum melongena seeds extract and its applications in degradation of Rose Bengal dye, antibacterial, catalytic reduction and antioxidant activity

The generation of copper oxide (CuO) nanoparticles using a biogenic extract (solanum melongena seeds) was the primary focus of this study. As prepared catalyst has been utilized for dye degradation of Rose Bengal and studies on Antibacterial and Antioxidants. The catalyst was characterized for its structural aspects by using Scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS), Powder X-ray Diffraction (PXRD), Fourier Transform - InfraRed spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) and UV–Visible DRS. The characterization results of XRD shows that the catalyst is in monoclinic phase. Copper Oxide is irregular in morphology and the average particle size is 47.97 nm which can be obtained using the SEM images and EDS spectra shows the Oxygen and Copper atoms presence which indicates the free from impurities of the fabricated biogenic CuO nanoparticles. FT-IR result indicated the stretching frequency of Cu–O appears at 487 cm−1. TGA data reveal that high-purity and thermally stable nanoparticles were fabricated, by the absence of significant weight losses at temperatures greater than 400 °C. Through UV–Visible DRS the calculate band gap was found to be 2.8eV. Based on the characterisation results the best catalyst was used to degrade the Rose Bengal dye within 60 min and also carried out the antibacterial and antioxidant activity which was found to be satisfactory when compared with their standard values.

Fabrication of kesterite Cu2ZnSnS4 thin films using sequentially sputtered multilayers of Cu2SnS3 and Zinc.

Radio-frequency sputtered Cu2ZnSnS4 (CZTS) thin films deposited on glass substrates were characterized. The film deposition was carried out in an argon atmosphere with RF powers of 200 W for zinc and 300 W for the CTS films. After the deposition, the films were annealed at temperatures ranging from 350 °C to 500 °C in a nitrogen and sulfur atmosphere. By using X-ray diffraction, the CZTS films were observed to crystallize in a tetragonal structure with some minor secondary phases in some samples. The absorption coefficient and optical band gap are identified by the ultraviolet-visible-near-infrared optical transmission measurements and the calculated band gap was found to range between 1.4 eV and 1.51 eV. This research comprehensively addresses the effects of layer thickness and annealing temperature on our CTS/Zn films. The annealing process was oberved to result in a significant improvement in electrical conductivity, particularly in films without secondary phases.

Studying the optical and electronic properties of Eu-doped CdSe phosphors using first principles calculations incorporating the spin orbit coupling method of DFT

We studied the electronic and optical properties of pure and Eu-doped CdSe phosphor materials using the first-principles calculation method, which is a feature of Density Functional Theory. The FP-LAPW method was employed for the study as incorporated in the Wien2k code. The GGA + U + SOC method of DFT was used for the first time in our study to investigate the electronic as well as optical characteristics of Eu-doped CdSe materials. Eu doping was done in two different ratios to study the effects of altered dopant concentration. The doping increased the band gap of the pure CdSe parental material. The calculated band gaps in our study were 0.42 eV for pure CdSe, 0.67 eV for a single Eu atom doped in CdSe, and 1.64 eV for two Eu atoms doped in CdSe. The measured electronic and optical characteristics of undoped i.e, pure CdSe and Eu-doped CdSe showed that the doping significantly changed the optical behavior of CdSe, which may be useful for applications in phosphor-converted LEDs.

Density functional theory study of cobalt sulfide as a counter electrode material for dye-sensitized solar cells

Abstract Dye-sensitized solar cells (DSSCs) are viewed as potential substitutes for traditional silicon-based solar cells due to their affordability, impressive performance in low-light conditions, eco-friendly energy production, and adaptability in solar product integration. The use of noble metals such as platinum as counter electrodes in DSSCs was initially limited by their high cost; however, cobalt sulfide has been recognized as a viable alternative due to its abundance, non-toxic properties, and cost-effectiveness. In this work, the crystal structure, electronic, optical characteristics and electrocatalytic activity of the tetragonal phases of cobalt sulfide are investigated through density functional theory with a quantum espresso package. The results obtained for the lattice parameter are a = b = 3.53 Å and c = 4.80 Å. The generalized gradient approximation and hybrid exchange correlation function yield bandgaps of 1.63 and 1.69 eV, respectively, which are consistent with the reported experimental values. An analysis of the density of states and the projected density was carried out to validate the accuracy of the calculated band gaps. Additionally, significant information was obtained from the optical properties through the calculation of the dielectric function. The findings reveal real and imaginary static dielectric constants of 11.85 and 0.13, respectively. Furthermore, the measured absorption and conductivity spectra exhibit promising attributes in the UV–visible range and good electrical conductivity. Moreover, the electrocatalytic activity was studied to analyze the adsorption energy of CoS and the electrolyte. Generally, the calculated electronic and optical properties of CoS crystals indicate their potential application as counter electrodes in dye-sensitized solar cells.

Green synthesis and characterization of TiO2 and Ag-doped TiO2 nanoparticles for photocatalytic and antimicrobial applications

TiO2 and Ag-doped TiO2 nanoparticles were synthesized using lemon grass plant leaf extract via a greener co-precipitation method. Plant biomolecules facilitated nanoparticle production, ensuring stability. Characterization involved XRD, FE-SEM, XPS, FT-IR, EDX, UV-DRS, HR-TEM and UV–Vis spectroscopy analyses, revealing tetragonal and cubic structures for TiO2 and Ag-TiO2, with average sizes of 11.96 and 41.8 nm, respectively. FT-IR confirmed characteristic bands, FE-SEM and HR-TEM analysis reveal that Ag-doped TiO2 nanoparticles primarily form irregular agglomerations, with interplanar spacings of 0.362 nm for the anatase (220) plane and 0.235 nm for the silver (111) plane and EDX determined elemental composition. UV–DRS calculated band gap values (3.3 eV for TiO2, 0.9 eV for Ag-TiO2). Photocatalytic performance against methylene blue dye under sunlight indicated higher degradation by Ag-TiO2 (96.96 %) than TiO2 (77.77 %). Antimicrobial testing showed superior activity of Ag-TiO2 over TiO2.

Influence of Sulfur Addition on The Physical and Photocatalytic Properties Biosynthesized Se-doped ZnO Nanoparticles

Abstract The objective of this study was to investigate the influence of Sulfur (S) addition to selenium-doped zinc oxide (Se-ZnO) nanoparticles on their physical properties and photocatalytic activity. S,Se-ZnO sample was prepared by adding 1wt% sulfur onto 4%Se-ZnO nanoparticles. In the synthesis procedure, microwave irradiation was used as heating power and matoa leaf extract was used as a bioreductor. The nanoparticles were characterized using UV-Vis Spectroscopy, X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM). The calculated band gap energies of Se-ZnO and 1% S,Se-ZnO are 2.38 eV and 2.62 eV, respectively. Both samples exhibit a hexagonal wurtzite structure. FESEM image of addition S reveals flower petal flake formations and decrease particle size of 187 nm. The photocatalytic activity of nanoparticles was evaluated through 4-nitrophenol (4-NP) degradation under UV-C irradiation. 1% S,Se-ZnO exhibits high photocatalytic efficiency compared to Se-ZnO, with a degradation percentage of 85.09% after 60 min and a reaction rate of -0.0315 min−1. Based on these results, the addition of S on Se-ZnO biosynthesized shows improve physical properties and efficient photocatalytic materials for pollutant removal.