Band Gap Energy Values Research Articles

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.

Physical Properties of HfO2 Nano Structures Deposited using PLD

On Quartz substrates, high purity transparent conductive the Di-Oxide of the (HfO2) Nano and micro-structure films were successfully coated. The method of (PLD) Deposition using Pulsed Laser, and the influence of laser energy was investigated. The XRD results revealed two distinct phases, cubic and monoclinic crystal shapes. Peaks in the Fourier-transform infrared (FTIR) spectra showed that HfO2 nanofilm was forming.The findings of the optical characteristics reveal an excellent transparency of nearly 80% (89 percent). As the laser wavelength decreases, the optical energy band gap values for Nanostructure of HfO2 were prepared, with values ranging from 5.24 to 5.53 eV. Also, the EDX results showed the appearance of hafnium peaks and oxygen peaks in varying proportions, which confirms that hafnium oxide is definitely obtained The results of the AFM reveal that when the pulsed laser intensity increases, the average grain diameter values increase from 52.96 to 74.54 nm. With regard to optimum pulsed laser energy, the based on I-V characterization, the generated factor ideality for created diodes was discovered to be decreasing, and the corresponding values of the barrier height grew. The ideality factor of the diode made the optimum pulsed laser energy (1800 mJ) was greater (n=3.1).

Improved photocatalytic activity triggered by UV light, as well as electrochemical sensing characteristics of MgO nanoparticles

ABSTRACT The current study’s objective was to investigate the potential applications of synthesised magnesium oxide nanoparticles (MgO NPs) as green fuel through solution combustion with leaves of tulsi (holy basil). The end product was further calcined for 3 h at 800°C to produce a well-crystalline nanomaterial. Transmission electron microscopy (TEM) examinations indicated a typical crystallite size of approximately 52 nm, determined by applying Scherer’s formula. The results from the scanning electron microscope (SEM) revealed a morphology that is clumped, puffy, and porous. The energy band gap (Eg) values for MgO NPs were determined to be 4.31 eV using DRS data, verifying the semiconductor behaviour of the NPs. Degradation experiments were conducted on two dyes, Fast Blue (FB) and Fast Orange (FO), exposed to UV light for 90 minutes. Under UV light, the photocatalytic degradation of FO (80.35%) and FB (80.5%) reached their maximum. A graphite paste electrode was used for cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and sensor investigations. The cyclic CVs of the MgO NPs-modified graphite paste electrode in 0.1 M NaOH were scanned at 10 to 50 mV/s to determine the specific capacitance values of 250.3 Fg−1. Based on the acquired EIS data, the MgO NPs used as the electrode displayed pseudocapacitive capacitor characteristics. Further, the proposed sensor was employed to determine the Pb2+ and Li+ ions in water and showed sensitivity in the order of 0.005 and 0.006 A. Therefore, MgO NPs synthesised via green solution combustion may have excellent applications as photocatalysts and electrochemical sensors.

Synthesis and Characterization of Low-Dimensional Quaternary Sulfides of Thallium, Tl2Cu2GeS4, Tl2Ag2GeS4, and Tl2Ag2SnS4.

Three new low-dimensional quaternary sulfides, namely, Tl2Cu2GeS4(1), Tl2Ag2GeS4(2), and Tl2Ag2SnS4(3) were synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction, spectroscopic, thermal, and photocatalytic studies. The compounds 1, 2, and 3, respectively, have centrosymmetric layered, noncentrosymmetric layered, and noncentrosymmetric one-dimensional structures, in which Cu+, Ge4+, and Sn4+ ions have tetrahedral coordination and Ag+ ion has linear, trigonal planar and tetrahedral coordinations. The monovalent thallium cations have TlS8 dodecahedral coordination and TlS7 and TlS6 coordination polyhedra of irregular shape. The compounds 1, 2, and 3 are semiconductors with the respective energy band gap values of 1.68, 2.02, and 1.90 eV. Compared to compounds 1 and 2, compound 3 has a higher efficiency value of 22.9% for the photodegradation of aqueous solution of methylene blue. Band structures and projected density of states of all three compounds were computed using density functional theory, and these results are in good agreement with experiments.

On the absorption coefficient of GaP1-xNx layers and its potential application for silicon photovoltaics

The absorption coefficient and the energy gap of GaP1-xNx layers has been obtained by spectroscopic ellipsometry for samples grown on Si(001) substrates by chemical beam epitaxy with N mole fractions in the range 0 ≤ x ≤ 0.081. The resulting absorption spectra exhibit a direct band-like behavior near the absorption edge. The absorption coefficient values increase with the N content, reaching values in the range α ∼ 1-2x104 cm−1 in the vicinity of the absorption edge below the original GaP direct bandgap, which are comparable to those obtained for high efficiency solar cell materials. Furthermore, dependence of the absorption coefficient with increasing N content points to a strong GaP Γ-like character of the conduction-band wave function of GaP1-xNx alloys near the Brillouin zone center at k = 0, as predicted by the band anticrossing model. Bandgap energy values obtained by spectroscopic ellipsometry are compared with previous values obtained by photoluminescence measurements on the same samples, observing a shift of about 50–100 meV. Finally, the value of the band anticrossing parameter coupling the N level and the host GaP conduction band has been obtained from the dependence of both, the bandgap and the absorption coefficient, with the N content (2.1 and 3.3 eV respectively).

Exploring Structural and Optical Properties of Nanoparticles of Barium Titanate and Iron doped Barium Titanate and Their Potential Application in Antibacterial Activity

Background: Barium Titanate (BaTiO3) is a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Methods: Pure and doped Barium Titanate (BTO) nanoparticles have been synthesized by the sol-gel method. Barium hydroxide octahydrate (Ba (OH)2.8H2O) and titanium (IV) iso-propoxide (Ti {OCH[CH3]2}4) were used as starting materials. Apart from pure Barium Titanate nanoparticles, Fe-doped BaTiO3 nanoparticles of three different concentrations: 0.1, 0.2 and 0.3 in mol% were prepared and characterized using X-ray diffraction (XRD), UV visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR). Results: From the X-ray diffraction pattern, the particle size was found to be varied in a range of 17-25nm. By using UV visible spectroscopy it was observed that the band gap energy of pure BaTiO3 NP is 3.2eV. As the pure BaTiO3 nanoparticles are doped with 0.1% Fe, the band gap reduces to 3.175eV. For BaTiO3 doped with 0.2% and 0.3% Fe, the band gap energy values are 2.709 and 2.652 respectively. FTIR spectra were used to analyze the vibrational modes of BaTiO3. From the result obtained from FTIR, we can see that the absorption spectrum ranges from 450cm-1-4000cm-1. The prominent peak of pure BaTiO3 is at 500cm-1 which is due to the vibration of the Ti-O band in crystal lattice. For BaTiO3 doped with Fe2O3, the wave number of the absorption peak is shifted from 500cm-1 in pure BaTiO3. The antibacterial studies were conducted on Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. Conclusion: Both pure and iron-doped Barium Titanate showed significant antibacterial properties, confirming the antibacterial property of Barium Titanate nanoparticles.

Microwave-Assisted Synthesis of CdS-MOF MIL-101 (Fe) Composite: Characterization and Photocatalytic Performance.

The present study outlines the synthesis of cadmium sulfide-metal-organic framework (CdS-MOF) MIL-101 (Fe) heterojunctions achieved via fast microwave-assisted reactions. Thus, different CdS-MOF MIL-101 (Fe) ratios were prepared to study their effectiveness as photocatalysts. These compounds were employed in the photocatalytic degradation of methylene blue (MB) under UV and visible irradiation. Structural, morphological, textural, compositional, and optical properties of the synthesized compounds determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize the structural, morphological, textural, compositional, and optical properties. Electrochemical impedance spectroscopy (EIS) was also employed to determine photovoltage and photocurrent densities. The resulting valence band offset (Vfb) and band gap energy values were utilized to construct an energy band scheme. Our research revealed that the CdS-MOF MIL-101 (Fe) heterojunction enhances the efficiency of electron-hole pair separation, thereby mitigating charge carrier recombination effects. Moreover, the type I electronic band structure established an efficient reaction mechanism, effectively suppressing the recombination of photogenerated electron-hole pairs. The photocatalytic system demonstrated exceptional behavior, achieving complete MB removal within 30 min of reaction time and exhibiting outstanding stability and reusability after four reaction cycles. These findings highlight the potential of the synthesized compounds in the field of wastewater treatment for organic pollutants, offering a promising alternative to current environmental issues.

Electrical conduction and optical characteristics of Li2O and Bi2O3 Co-doped zinc-phosphate glassy nanocomposites: A critical observation of mixed ionic electronic effect

In the present report, the combined effects of the co-doping of metal oxide (Bi2O3) and Lithium oxide (Li2O) into the glassy matrix with chemical composition xLi2O-(0.45-x)Bi2O3-(0.15ZnO-0.40P2O5) (x = 0.05, 0.15, 025, and 0.35 mol%) are investigated thoroughly. The FESEM and X-ray diffraction data affirm the crystalline nature of the studied glassy composites. The obtained band gap energy values are declined from (3.68–3.17) eV, while the Urbach energy values are declined from (0.38–0.27) eV. Moreover, the mechanism responsible for AC conductivity has been analyzed using Almond–West formalism and Jonscher's universal power law. The observed rise in both AC and DC conductivity in the glass samples is attributed to the mixed ionic electronic effect. In the ionic diffusion model, an increased defect site concentration improves Li+ ion migration through percolation channels. The reduction in both electrostatic binding energy and strain energy lowers the Anderson-Stuart activation energy, facilitating Li+ ion migration and enhancing conductivity. Additionally, in the small polaron hopping model, an increase in the density of defect states suggests more defect sites that facilitate electronic hopping, creating deep localized states and transitions between localized and extended states. Replacing a Bismuth atom with a Lithium atom increases the number of non-bridging oxygen, enhancing the conduction band tail, reducing the energy needed for hopping conductivity, and increasing conductivity.

Functionalization of single-walled aluminum nitride nanotube with amino acids using the first principle's study

In this study, we investigate the functionalization of aluminum nitride nanotube (AlNNT) with amino acids (Phenylalanine, Arginine, and Glutamine) using first-principle density functional theory (DFT) calculations. DFT methods were applied to model the interactions between amino acids and AlNNT, exploring the structural and electronic features of the functionalized systems, and examining various aspects of the structures, including their geometry and electronic properties, such as bond lengths, bond angles, total energy, formation energy, band structure, chemical potential, density of states (DOS), projected density of states (PDOS), charge transfer, and electron difference density. The (5, 5) AlNNT exhibits an energy bandgap value of 3.31 eV, implying its semiconducting nature. Furthermore, the pure system's chemical potential was -4.12 eV. The DOS examination shows that the pristine system's band structure profile and energy states match well. Notably, the valence band displays a more pronounced level of energy hybridization compared to the conduction band, which is reflected in the band structure. Functionalization of AlNNT with amino acids enhances the p character and polar covalency, thereby increasing the percentage ionic character and Gibb's free energy of solvation which are essential parameters to determine the aqueous solubility.

Improving the energy storage efficiency and power density of polymer blend in combination with Ti3C2Tx for energy storage devices

Polymer blend-based dielectrics are extensively used because of their broad working temperature range, quick discharging speed, and high power density. The solution casting approach is used to prepare the PVDF/PMMA- Ti3C2Tx nanocomposite flexible energy storage films. The morphology results show that the composite has a homogeneous and dense microstructure. The structural study shows the composition of thin films and confirms the existence of the PVDF β-phase. The thermal analysis showed 31.36 % crystallinity for 20 wt% of nanocomposite (NCs). The values of band gap energy reduced from 3.07 eV to 2.65 eV with increasing Ti3C2Tx concentration (15 wt%). It was found that the almost high dielectric constant values of (̴205) at 100 Hz and loss of 0.078 were suggestive of increased interfacial polarization. The maximal energy density of the NCs is 1.28 J/cm3, and its power density is 4.86 MW/cm3 for 15 wt% NCs. The conductivities of 15 wt% composite increase to 10−9 –10−7 S.cm−1 at 100 Hz, and then it reaches nearly 10−3 S cm−1 when the frequency is raised to 1 MHz. The 2D MXene nanofiller and PVDF macromolecular chain have an improved interface interaction, which results in excellent complete electrical characteristics. The rise in residual polarization can be inhibited by adding PMMA. In this work, adding 2D Ti3C2Tx MXene to PVDF/PMMA blends offers a viable way to create materials that are highly effective at storing energy in capacitors.

H2S gas sensing behavior of 2-D V2O5 nanowire network structure

In this study, a nanowire network-based V2O5 nanostructure, designed as the active surface in H2S gas sensors, was produced using an environmentally friendly method known as hydrothermal synthesis. The morphological, structural, and electrical properties of the produced nanostructure were characterized using various measurement techniques. XRD, SEM, and EDX analyses confirmed that the nanostructure was in a pure monoclinic phase, had a two-dimensional (2-D) nanowire network morphology, and was deposited stoichiometrically. From UV–Vis analysis, the energy band gap value of the nanostructure was calculated to be 2.65 eV. In gas sensing measurements conducted between 27 °C and 102 °C, the optimal operating temperature of the fabricated sensor was determined to be 42 °C. At this temperature, which is close to room temperature, the sensor exhibited a high sensitivity of 21.16 % for 50 ppm H2S gas, along with good selectivity, stable repeatability, and baseline stability. Moreover, for 2 ppm H2S gas, the response and recovery times were 39 s and 58 s, respectively. A comprehensive electrical analysis of the sensor was carried out through impedance spectroscopy measurements over a wide temperature range. Our findings indicate that the 2-D V2O5 nanowire network structure (NNS) results in several notable effects, including low operating temperature, high selectivity, and stability for H2S gas, demonstrating considerable potential for industrial applications.

DFT Insights into the Structural, Mechanical, Electronic and Optical Properties of Novel InZnCl<sub>3</sub> and InCdCl<sub>3</sub> Chloro-Perovskites

The ABX3 perovskite materials have recently emerged as one of the most promising materials for optoelectronic applications. In the present study, novel perovskites in the form of InZnCl3 and InCdCl3 are computationally investigated to determine their key characteristics, including structural, mechanical, electronic, and optical characteristics. These characteristics were evaluated using the density functional theory (DFT) implemented in the quantum espresso code. The results indicated that both materials exhibit chemical, dynamic, and mechanical stability. Moreover, these perovskites are predicted to be ductile, rendering them suitable for a broad array of optoelectronic applications, including solar cells. The electronic band structure and the density of states of the materials revealed their characteristics as indirect semiconductors with band gap energy values of 0.96 eV for InZnCl3 and 1.83 eV for InCdCl3 perovskites. The optical properties calculations also unveiled that these perovskites possess strong absorption in the visible-ultraviolet spectrum (up to 106 cm−1) and low reflectivity. The calculated refractive index and extinction coefficient of the compounds were also predicted in this study. These collective findings strongly suggest the potential applications of these novel materials in optoelectronic devices.

Synthesis of CuO/Fe3O4 Nanocomposite for enhanced solar thermal desalination

Nanoparticle (NPs) have attracted the attention of scientists and researchers in water remediation due to the improvement in its processability, and its cost effectiveness. The present work analyzed the synergistic effect of CuO (NPs) with different ratios (0, 0.5, 0.6, 0.7, 0.8, 0.9 and 1 wt %) on the structural, and optical properties of Fe3O4 (NPs), that can be used in water desalination process. The general methodology for preparation and structural properties of CuO (NPs), Fe3O4 (NPs) and CuO/Fe3O4 (NCs) were analyzed by (XRD) and (TEM) measurements. The morphological combination of (SEM) with (EDX), were used for determining the elemental identification of CuO/Fe3O4 (NCs). The characterization topography was found to be strongly affected by the change of the CuO concentration. Furthermore, the Urbach energy (EU), steepness parameter (σ), electron-phonon interaction (Ee-p), optical band gap (Eg), refractive index (n) and optical conductivity (σopt) were calculated. The optical absorption studies in the UV–Visible region, revealed that the CuO/Fe3O4 (NCs) was found to be direct allowed transition, and the energy bandgap value decreased from 2.52 eV to 2.15 eV based on the percentage change of CuO (NPs) in CuO/Fe3O4 (NCs). Moreover, the value of thermal conductivity (k), and thermal efficiency (η), showed an increase with the increase of the ratio of CuO (NPs), which may be an indication for opening an innovation way that can satisfy the need of seawater desalination technology.

The Influence of Cuprum (II) Acetate (Cu (CH3COO)2) Dopant and Heating Temperature in The Fabrication of Thin Films of Barium Strontium Titanate (Ba0.4Sr0.6TiO3)

Abstract Barium Strontium Titanate (BST), or BaxSr1-xTiO3, is an excellent ferroelectric material that is widely used on thin film applications in microelectronic devices, making BST very essential to the tech industries. This research aims to fabricate Cuprum doped BST thin films at low temperature using the Chemical Solution Deposition (CSD) and spin coating technique, and then to analyze the thin film’s band gap energy from the UV-Vis curve, XRD Spectral and EDAX. The advantage lies in the use of low temperatures in which it allows a significant energy savings compared to other studies. Using the Kubelka-Munk method with the Tauc Plot relation, the bandgap energy values for each BST substrates were obtained. Without Cuprum (II) Acetate dopant, the Band Gap values of the thin film samples are 3.84 eV and 3.77 eV. With 3% concentration of Cuprum (II) Acetate dopant, we obtained smaller Band Gap values, which are 3.74 eV and 3.71 eV. Based on the XRD spectral analysis, the lattice parameters were determined with a tetragonal crystal structure. However, according to the EDAX analysis, the elemental composition obtained is not yet stoichiometric. This research is important to serve as a reference for other researchers and manufacturers to opt into fabrication of thin films with lower energy cost, provide guidance for researchers to have more flexibility in their own thin film fabrication.

Polyurethanes derived from triazole-based monomers and their application as fluorescent probe for Zn2+

Polyurethanes are one of the most encountered polymer classes in both industry and scientific research, with their tremendous physical and chemical properties, as well as numerous advantages such as a wide range of raw materials, the ratio of groups to be used during polymerization and adjustable mechanical properties. In this study, four distinct polyurethanes were synthesized using toluene diisocyanate (TDI) and hexamethylenediisocyanate (HMDI) derived from Schiff bases formed by reacting 3,5-diamino-1,2,4-triazole (DAT) and 4 different aldehydes (2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, 2-hydroxy napthaldehyde, o-vanillin). The structural characterizations of the synthesized Schiff bases and polyurethanes were elucidated using 1H- 13C NMR and FT-IR, thermal stability was assessed via TGA, molecular weights of the polymers were determined using GPC, electrochemical properties were evaluated by CV, and optical properties were examined using UV–Vis and fluorescence spectrophotometry. The molecular weights of polyurethanes ranged from 4500 to 10300 Da. TGA analysis of the synthesized polyurethanes demonstrated significant thermal stability, maintaining integrity up to 310 °C. The band gap energy (E’g) values of polyurethanes were found to range from 2.30 to 2.51 eV, which is lower than that of their corresponding monomers, exhibiting semiconductor properties. It was determined that DATSA-PU, one of the synthesized polyurethanes, exhibited potential as a “turn-on” fluorescent sensor for Zn2+ ion with a LOD value of 2.03 x 10-7 M.

Influence of d-d transition electrons and thickness variations on the excited-state optical properties: Nonlinear optical characterization of Cr2O3 thin film

The structural, morphological, linear, and nonlinear optical properties of Cr2O3 thin films with different thicknesses deposited by the thermal deposition, were measured. The structural and morphological parameters of films, determined by XRD, FESEM, and AFM images, are compared to the linear and nonlinear optical characteristics of these media. The bandgap of prepared thin films was obtained from DRS spectra. The electron effective mass (me∗/m0), linear refractive index (n0), optical static, and high frequency dielectric constant (ε0 , ε∞) values were calculated by using the band gap energy values. Increasing the thicknesses of thin films causes to decrease the band gap, an increase RMS, increase the size of nanoparticles and the nonlinear responses of thin films. The high magnitude of n2, and β belonged to the Cr2O3 (300 nm-thickness) in the order of 10−5 cm2/W, and 10−1 cm/W respectively. The fluctuations in nonlinear responses observed at different thicknesses are attributed to d-d transitions and intraband scattering of equilibrium electrons influenced by laser radiation, as indicated by the nonlinearity data. The considerably elevated refractive non-linearity values in the analyzed film materials suggest their potential for practical applications in optoelectronic devices.

Crystal Structure, Optical, Photoluminescence, Raman, and Magnetic properties for Sm-doped Cr-Mg-Bi Ferrites using sensor

The current work,A series of rare earth Sm3+ ion substituted Cr-Mg-Bi ferrites Cr0.7Mg0.2Bi0.1SmxFe2-xO4 (x = 0.00, 0.02, 0.04, and 0.06) have beensynthesized by thesol-gel auto-combustion method. The XRD, FESEM, HRTEM,UV-Vis, FTIR, Raman spectroscopy, Photo Luminesce and Magnetic Properties analysis have been used to investigate structural, morphological, optical, Raman spectroscopy, Photo Luminesce and Magnetic Properties. Every sample contains a single-phase spinel structure, as confirmed by XRD.The substitution of Sm3+ ions is found to increase the lattice parameter from 8.258–8.248Å.A monotone diffraction peak (311) is visible near small angles of degrees (35.33 to 35.13). The Debye-Scherrer equation, the nanoparticles' crystallite size ranges from 35.357–54.778 nm.FE-SEMs reveal a spherical grain that groups and has a porous form, with particles 38.13 to 53.28 nmin size.HR-TEM micrographs illustrate spherical morphology and their average particle size decreases from 55.32 to 65.42 nm. The selected area electron diffraction (SAED) pattern confirms the crystal planes which were revealed from XRD calculations.The spinel structure was confirmed by FTIR spectroscopy, which found 414 cm-1 and 516 cm-1 vibrational band at the octahedral and tetrahedral sites.As the concentration of Sm3+ rises, the direct and indirect band gap energy values determined from UV-Vis show an increase and decrease.The generated NPs' semiconducting nature is confirmed by the strong correlation between the g-value and particle size change.Photoluminescence (PL) investigation shows that all processed samples have four bands.(i) peak centered at 412 nm, which is near-band edge emission and corresponds to the ultraviolet (UV) band,(ii) The violet band has a high-intensity peak at 434 nm,(iii) The blue band is related to a low-intensity, sharp peak located at 466 nm, and (iv) A broad peak at 502 nm with a very low intensity distinguishes the green band.The Raman spectroscopy investigation revealed that the CMBSF nanoparticles had a mixed spinel structure. The magnetic investigation shows that when the Sm content of ferrites increases, saturation magnetization drops from 39.86 to 33.16 emu/g.The sample's coercivity (Hc) increases from 16.06 to 21.90 KOe with Sm substitution.

Insights into the structural and optical properties of [formula omitted] substituted [formula omitted]

Y2−xTbxMo4O15(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7) were successfully synthesized using citrate nitrate combustion method. The characterization techniques used in the present study involves X-ray Diffraction, Raman and FTIR spectroscopy, transmission electron microscopy, UV-Visible spectroscopy and photoluminescence spectroscopy. Structural analysis concludes that the compound crystallizes in monoclinic phase with space group P21/c as confirmed through Rietveld refinement. Diffuse reflectance spectra show a high absorption in the wavelength range 250 – 400 nm and the band gap energy values are evaluated. Photoluminescence spectra show an intense green emission at 545 nm and luminescence quenching of Y2−xTbxMo4O15 occurs beyond the concentration, x=0.4.The critical distance evaluated using Blasse’s expression is 9.24 Å and dipole-dipole interaction exists between the Tb3+ions which is confirmed through Dexter theory. The optimized nanophosphor has internal and external quantum yields equal to 11.01 % and 9.91 %, respectively, and has a decay time of 0.101 ms. These results strongly suggest that the prepared nanophosphor can be used as a green phosphor in pc-LEDs.

Synthesis, crystal structure, spectroscopic, electronic and vibrational properties of N′-[(E)-3-pyridinylmethylene]nicotinohydrazide trihydrate: Experimental and computational study

N′-[(E)-3-pyridinylmethylene]nicotinohydrazide trihydrate (C12H10N4O·3(H2O)) was synthesized and its structure was determined by single crystal X-ray diffraction method. X-ray analysis showed that the compound crystalized in the triclinic system P-1 with a = 7.1134 (3) Å, b = 10.0208 (4) Å, c = 10.3601 (4) Å, α = 96.386 (3)°, β = 96.995 (3)°, γ = 101.219 (4)°, V = 712.05 (5) Å3 and Z = 2 and exhibits that the title compound (I) consists of N′-[(E)-3-pyridinylmethylene]nicotinohydrazide (II) (C12H10N4O), and three water molecules of crystallization. The two water molecules are attached to the third water molecule through intermolecular two OH…O hydrogen bonds. At the same time, this water molecule is linked to the NH amide group of the hydrazone by an intermolecular NH…O hydrogen bond. Hirshfeld surface (HS) analyses were carried out are to visualise the intermolecular interactions in the crystals of Compound I. The geometric optimization of the titled compound has been carried out by different computational methods such as by Hatree Fock (HF) and Density Functional Theory (DFT) methods with the 6–311++G (d,p) basis set. The vibrational frequency, dipole moment (μ), polarizability (α), hyperpolarizability (β), and electronic properties including the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO–LUMO) of the compound have been calculated at the level of both theories. In the results of crystal analysis and geometry calculations of the compound I, it was observed that intermolecular hydrogen bonds, N2H2A…O3, O3H31…O2 and O3H32…O4, were formed. The energy band gap (Eg = ELUMO-EHOMO) values were also obtained by using ELUMO and EHOMO at the level of both theories. The value of equilibrium (ground state) dipole moment of the studied molecule was calculated to be 8.31 Debye in B3LYP and 7.55 Debye in HF. The calculated hyperpolarizability values at the B3LYP/6–311++G(d,p) of the compound are 2.53 × 10−30 esu and this value corresponds to 6.79 times the hyperpolarizability value of urea.

Computational insight on K2AuBiX6 (X = F, Cl, Br, I) double perovskites to comprehensively investigate mechanical, optoelectronic, and thermoelectric features for green energy applications

In this article, we investigated the structural, elastic, electronic, optical, and thermoelectriccharacteristics of K2AuBiX6 (X = F, Cl, Br, and I) using density functional theory (DFT). To verify the stability of the cubic structure tolerance, octahedral factors, and formation energy have been determined. The mechanical stability has been governed by Born stability criteria. These parameters ensure its strength, ductility, brittleness, and anisotropy. The bandgaps of K2AuBiF6, K2AuBiCl6, K2AuBiBr6, and K2AuBiI6 have been determined using the TB-mBJ potential. The calculated values of energy band gaps are 2.88, 2.02, 1.38, and 0.95 eV, respectively. These materials exhibit a broad absorption in visible regions, a refractive index range of around 1–3, and low light scattering, which makes them ideal for optoelectronic applications. In addition, the figure of merit (ZT) values for these compounds at room temperature are 0.76, 0.78, 0.77, and 0.80, ensuring their suitability for use in thermal devices.