Prominent Peak Research Articles

Multiple stimuli-responsive double perovskite structured Ca2MgWO6: x % Eu3+ (x = 1–11 mol) red-emitting luminescent systems to combat counterfeiting

The rapid escalation of counterfeiting activities in recent years has posed significant challenges across diverse fields, such as pharmaceuticals, currency, luxury goods, and electronics. In response, inorganic phosphors have emerged as promising tools to combat counterfeiting due to their inherent durability and stability. The present work focuses on the synthesis of Ca2MgWO6:x % Eu3+ (x = 1–11 mol) luminescent systems via a gel-combustion route. The structural analysis of the synthesized luminescent systems confirmed a monoclinic crystal phase with a P21/n space group. The morphological study of the luminescent system revealed a network-like structure comprising interconnected particles. Photoluminescence emission spectra show a prominent red emission peak at 616 nm, corresponding to the 5D0→7F2 4f–4f electronic transition of Eu3+ ions in the host matrix. The emitted red light demonstrates a color purity and quantum efficiency of 93.1 % and 77.41 %, respectively. The anti-counterfeiting security patterns were developed using the Ca2MgWO6:x % Eu3+ (x = 9 mol) luminescent system showcase virtually invisible under normal light. However, developed patterns exhibit vivid red luminescence when exposed to multiple stimuli UV light at 365 and 395 nm, which envisages the versatility of the systems for enhancing product authentication and protecting against fraudulent activities across multiple industries. The aforementioned results demonstrated the efficacy of Ca2MgWO6: Eu3+ luminescent systems for integration into advanced security measures.

Synthesis and antifungal efficacy of chitosan nanoparticles against notorious mycotoxigenic phytopathogens

Pathogenic fungi such as Fusarium verticillioides, Alternaria alternata, and Macrophomina phaseolina pose significant threats to agriculture and human health due to their production of carcinogenic mycotoxins. This study explores the antifungal potential of chitosan nanoparticles (ChNPs) against these fungi. ChNPs, synthesized via an ionic gelation method, exhibited a prominent UV-visible absorption peak at 250 nm, confirming successful nanoparticle formation. X-ray diffraction patterns revealed their amorphous structure, while FTIR analysis identified key functional groups, including hydroxyl and amine groups, with an average particle size of 50 nm. Antifungal assays demonstrated that ChNPs inhibited fungal growth in a concentration-dependent manner. Specifically, for F. verticillioides, ChNPs reduced growth by 20-60% at concentrations ranging from 0.03 to 0.15%, achieving complete inhibition at 0.21%. Similarly, A. alternata exhibited a MIC of 0.24%, and M. phaseolina reached a MIC of 0.26% for complete growth suppression. Higher concentrations of ChNPs caused pronounced structural alterations in the fungi, including discoloration, fragmentation, and distortion of hyphae and conidia/sclerotia, which were linked to significant metabolic changes within the fungal cells. This study highlights the effectiveness of ChNPs as robust antifungal agents, demonstrating their ability to disrupt fungal morphology and enzyme activities

Visible light photocatalytic reduction of Toxic Chemical Organophosphate Monocrotophos using reduced Graphene Oxide derived from bamboo leaves

In this study, graphene oxide (GO) was synthesized from waste bamboo leaves using a pyrolysis and ultra-sonication technique. UV-visible spectroscopy revealed a prominent absorption peak at 230nm, while Raman spectroscopy confirmed the presence of characteristic D-band (1340cm⁻¹) and G-band (1596cm⁻¹). XRD analysis showed a peak at 11.5°, corresponding to a lattice spacing of 3nm, and SEM/TEM imaging demonstrated the formation of multi-layered graphene sheets. The synthesized GO was evaluated for the photocatalytic degradation of the organophosphate pesticide monocrotophos under visible light. At a concentration of 25mg/L, graphene exhibited a removal efficiency of 98% with a degradation rate of 0.036 ppm/min, following a Langmuir isotherm and pseudo-first-order kinetic model. The significance of this study lies in the potential environmental application, offering an economical and sustainable solution for the decontamination of pesticide-contaminated water sources. The method could contribute significantly for reducing environmental pollution and addressing global water safety challenges.

EFFECTS OF SYNTHESIS TEMPERATURE ON THE STRUCTURAL AND OPTICAL PROPERTIES OF CaAl2O4: Eu2+, Dy3+NANOPARTICLES

Calcium aluminate phosphor nanomaterials co-doped with europium and dysprosium (CaAl2O4: Eu2+, Dy3+) were prepared using a facile solution combustion technique. The structural and optical properties were investigated. The X-ray diffraction (XRD) results confirmed the presence of the monoclinic phase in all the samples, with few impurity phases in the samples synthesized at 300°C and 400°C. The Fourier-transform infrared analysis gave the expected chemical combustion results of the final product with few traces of Ca3Al2O6 impurities at low and very high synthesis temperatures. The XRD patterns displayed diffraction angles of the major peaks shifting to higher 2 theta as the synthesis temperature increased. This is attributed to an increase in particle sizes, which led to an increase in lattice parameters. The intensity of the prominent peak increased up to 500°C due to improved crystal quality. The crystallite sizes of the as-prepared samples were determined using the Debye-Scherrer equation. It was noted that there is variation in the crystallite sizes with synthesis temperature. The UV-Vis graph shows that absorption edges also shifted to lower wavelengths with an increase in synthesis temperature. It was noted that the band gap increased with an increase in synthesis temperature up to 500°C, but at temperature of 1000°C, the band gap was observed todecrease. Scanning electron microscope micrographs showed that the samples had irregular shapes with pores and cracks. The study provides a simple route to synthesize CaAl2O4: Eu2+, Dy3+ phosphors with optimum synthesis temperature, producing the most crystalline sample for use in lighting devices.

Morphological and structural analysis of monodispersive silica nanoparticles fabricated by stober method for self-cleaning applications

Abstract In this work, silica nanoparticles have been synthesized via the Stober process on a p-type silicon substrate by spin coating method. Structural and morphological studies have been carried out by x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Microstructural analysis by Raman spectroscopy displays a prominent peak at 524 cm−1 which corresponds to crystalline silicon. Further, the elemental study by using energy dispersive x-ray spectroscopy (EDX) confirms the presence of silica with no other impurities. Besides, the wettability property has been studied by contact angle measurement and found to be around 130° for the 6-layer coated thin film which is quasi-super-hydrophobic. The wettability results obtained signify promising properties for the development of self-cleaning devices and applications.

Discovery of superconductivity and electron-phonon drag in the non-centrosymmetric Weyl semimetal LaRhGe3

We present an exploration of the effect of electron-phonon coupling and broken inversion symmetry on the electronic and thermal properties of the semimetal LaRhGe3. Our transport measurements reveal evidence for electron-hole compensation at low temperatures, resulting in a large magnetoresistance of 3000% at 1.8 K and 14 T. The carrier concentration is on the order of 1021/cm3 with high carrier mobilities of 2000 cm2/Vs. When coupled to our theoretical demonstration of symmetry-protected almost movable Weyl nodal lines, we conclude that LaRhGe3 supports a Weyl semimetallic state. We discover superconductivity in this compound with a Tc of 0.39(1) K and Bc(0) of 2.2(1) mT, with evidence from specific heat and transverse-field muon spin relaxation. We find an exponential dependence in the normal state electrical resistivity below ~50 K, while Seebeck coefficient and thermal conductivity measurements each reveal a prominent peak at low temperatures, indicative of strong electron-phonon interactions. To this end, we examine the temperature-dependent Raman spectra of LaRhGe3 and find that the lifetime of the lowest energy A1 phonon is dominated by phonon-electron scattering instead of anharmonic decay. We conclude that LaRhGe3 has strong electron-phonon coupling in the normal state, while the superconductivity emerges from weak electron-phonon coupling. These results open up the investigation of electron-phonon interactions in the normal state of superconducting non-centrosymmetric Weyl semimetals.

Optimisation of laser surface ablation of alumina/GO coating on AZ31D magnesium alloy using Cuckoo Search Algorithm method

ABSTRACT Graphene oxide (GO) and alumina (Al2O3) work in concert to give magnesium alloys advantageous surface qualities and protection from adverse environments. This paper aims to investigate the effect of laser surface treatment on plasma sprayed alumina-graphene oxide (GO) coating on AZ31D magnesium alloy. Key ablation quality responses; HAZ width, surface roughness and ablation rate were correlated with laser parameters using the Response Surface Methodology and optimised using the metaheuristic Cuckoo Search Algorithm Method. Laser power significantly influenced all ablation characteristics of the composite coating. The addition of 1.5 wt% GO in the alumina coating caused a significant reduction in HAZ width (43.32%), surface roughness (25.11%) and ablation rate (76.58%) when treated with optimal combinations of laser power (8 W), scanning speed (950 mm/s) and frequency (78.2 kHz). The surface quality was characterised by smooth textures, and resolidified splats along with deep pits when ablated with lower and intermediate power whereas surfaces ablated with higher power showed debonded splats with peripheral surface destruction. While a prominent 2D peak at 16 W confirmed the presence of GO layers during high-power laser contacts, the ID/IG ratio below unity across all specimens indicated minimal defect concentrations.

Noradrenaline dose cutoffs to characterise the severity of cardiovascular failure: Data-based development and external validation.

The vasopressor dose needed is a common measure to assess the severity of cardiovascular failure, but there is no consensus on the ranges of vasopressor doses determining different levels of cardiovascular support. We aimed to identify cutoffs for determining low, intermediate and high doses of noradrenaline (norepinephrine), the primary vasopressor used in intensive care, based on association with hospital mortality. We conducted a binational registry study to determine cutoffs between low, intermediate and high noradrenaline doses. We required the cutoffs to be statistically rational and practical (rounded to the first decimal and easy to remember), and to result in increasing mortality with increasing doses. The highest noradrenaline dose in the first 24 h after intensive care unit (ICU) admission was used. The cutoffs were developed using data from 8079 ICU patients treated in the ICU at Kuopio University Hospital, Finland, between 2013 and 2019. Subsequently, the cutoffs were validated in the eICU database, including 39,007 ICU admissions to 29 ICUs in the United States of America in 2014-2015. The log-rank statistic, with the Contal and O'Quigley method, was used to determine the cutoffs resulting in the most significant split between the noradrenaline dose groups with regard to hospital mortality. The two most prominent peaks in the log-rank statistic corresponded to noradrenaline doses 0.20 and 0.44 μg/kg/min. Accordingly, we determined three dose ranges: low (<0.2 μg/kg/min), intermediate (0.2-0.4 μg/kg/min) and high (>0.4 μg/kg/min). Mortality increased, whereas the number of patients decreased consistently with increasing noradrenaline doses in both cohorts. In the development cohort, hospital mortality was 6.5% in the group without noradrenaline administered and 14.0%, 26.4% and 40.2%, respectively, in the low-dose, intermediate-dose and high-dose groups. Compared to patients who received no noradrenaline, the hazard ratio for in-hospital death was 1.4 for the low-dose group, 4.0 for the intermediate-dose group and 7.5 for the high-dose group in the validation cohort (p < .001). The highest noradrenaline dose is a useful measure for quantifying circulatory failure. Cutoffs 0.2 and 0.4 μg/kg/min seem to be suitable for defining low, intermediate and high doses.

Structural and optical features improvement of Tm3+–doped B2O3 – BaSO4 – TeO2 – Na2O glasses

Highly transparent sodium-telluro-sulphate-borate glasses doped with thulium (Tm3+) were useful for variety of purposes. Thus, a new type of glass system composed of (57- x)B2O3 – 20BaSO4 – 13TeO2 – 10Na2O – (x)Tm2O3 (x = 0.2 to 0.8 mol%) was produced via standard melt-quenching route. The impacts of different Tm3+ contents on the glasses’ physical and optical characteristics were ascertained for the first time. The amorphous nature of the samples was validated by their XRD patterns, and Raman analysis revealed the presence of various chemical functional groups. These samples exhibited Urbach energy, direct band gap and indirect band gap between 0.088 – 0.262 eV, 2.458 – 2.545 eV and 2.098 – 2.425 eV respectively. UV-Vis-NIR absorbance displayed six prominent peaks at 464, 657, 686, 795, 1210 and 1680 nm characteristics to various electronic transitions of Tm3+. The prepared glass composition could be effective in the production of solid-state lasers with a narrow wavelength range.

Photoresponse enhanced CsPbBr3 quantum dots quantum-confined in mesoporous PCN-600 single crystal microwires

In this work, the CsPbBr3 quantum dots (QDs) are encapsulated into the mesoporous iron-based metal-organic framework (PCN-600) by using a two-step solvothermal method. The success formation of CsPbBr3@PCN-600 composite is confirmed via SEM, TEM, XRD, FTIR, EDS and other measurements. Besides, the characterization of fluorescence lifetime of CsPbBr3@PCN-600 composite reveals the presence of the electron transfer between PCN-600 and CsPbBr3 QDs. Especially, CsPbBr3@PCN-600 exhibits a prominent emission peak at 473 nm due to the quantum confinement effect, and the photoluminescence quantum yield of CsPbBr3 QDs protected by the mesoporous PCN-600 increases to 71% compared to 52% of the pristine CsPbBr3 QDs. Also, the protection of CsPbBr3 QDs by the PCN-600 channel enhances the luminescence stability, thermal stability and blue-light stability of CsPbBr3. In fact, under light illumination, the photogenerated carriers from the encapsulated CsPbBr3 QDs could be captured by catalytically active sites on the inner surface of the PCN-600 channel. This charge capture effect can increase the photocurrent and implies much effective separation of electron-hole pairs of the CsPbBr3@PCN-600 composite. These results make this composite a promising candidate for high-performance photoelectronic devices.

Undoped and Eu doped LaCa₄O(BO₃)₃ phosphors: Thermoluminescence characteristics with a focus on kinetic parameters, anomalous heating rate, and dose response

The thermoluminescence (TL) properties of LaCa₄O(BO₃)₃ (LACOB) phosphors, both undoped and doped with 0.5 % Eu³⁺, were synthesized using a microwave-assisted sol-gel method and analysed under beta irradiation doses ranging from 0.1 Gy to 700 Gy. The TL glow curves revealed prominent peaks at 100 °C and 285 °C for the Eu-doped sample. Activation energy values were calculated using the Hoogenstraaten and Booth-Bohun-Parfianovitch methods, yielding 1.52 eV and 1.48 eV for the undoped sample, and 2.07 eV and 2.01 eV for the Eu-doped sample, respectively. Eu³⁺ ions introduced deeper traps and enhanced the thermal stability of the material. Anomalous increases in TL intensity with rising heating rates were observed, deviating from typical thermal quenching behaviour; this phenomenon was explained using a semi-localized transition (SLT) model. The TL reusability measurements demonstrated a standard deviation of less than 5 %, indicating consistent and reliable performance across multiple cycles. The TL glow curve deconvolution identified six distinct peaks in the undoped sample, while the Eu-doped sample showed a more complex trap structure with eight peaks, indicating the introduction of additional or modified trapping sites by Eu doping. The figure of merit (FOM) values obtained from the deconvolution analysis were all below 2.5 %, indicating a good fit between the observed and fitted TL signals. These findings suggest that Eu³⁺-doped LACOB is a robust material for radiation dosimetry, with its enhanced sensitivity, stability, and versatility across various dosimetric applications.

Low-temperature thermopower and phonon-drag effect in the quasi-one-dimensional cobaltate Ba3Co2O6(CO3)0.7

The quasi-one-dimensional cobaltate Ba3Co2O6(CO3)0.7 exhibits a high thermoelectric performance characterized by the large thermopower and high electrical conductivity above room temperature, while the low-temperature transport properties have been less investigated so far. Here, we systematically measure the thermopower of single-crystalline Ba3Co2O6(CO3)0.7 samples at low temperatures. The temperature dependence of the thermopower near room temperature is similar to that of other thermoelectric cobaltates, such as layered cobaltates, but exhibits a sample-dependent prominent peak structure near T = 40 K. We evaluate the sample dependence of the carrier density and the mobility and find that the saturation effect of phonon drag is essential for the observed peak structure in the thermopower. The enhanced thermopower utilizing a phonon-drag effect in the present material may be crucial for low-temperature thermoelectrics.

Rotary excitation of non-sinusoidal pulsed magnetic fields: Towards non-invasive direct detection of cardiac conduction.

There is a need for high resolution non-invasive imaging methods of physiologic magnetic fields. The purpose of this work is to develop a MRI detection approach for non-sinusoidal magnetic fields based on the rotary excitation (REX) mechanism which was previously successfully applied for the detection of oscillating magnetic fields in the sub-nT range. The new detection concept was examined by means of Bloch simulations, evaluating the interaction effect of spin-locked magnetization and low-frequency pulsed magnetic fields. The REX detection approach was validated under controlled conditions in phantom experiments at 3 T. Gaussian and sinc-shaped stimuli were investigated. In addition, the detection of artificial fields resembling a cardiac QRS complex, which is the most prominent peak visible on a magnetocardiogram, was tested. Bloch simulations demonstrated that the REX method has a high sensitivity to pulsed fields in the resonance case, which is met when the spin-lock frequency coincides with a non-zero Fourier component of the stimulus field. In the experiments, we found that magnetic stimuli of different durations and waveforms can be distinguished by their characteristic REX response spectrum. The detected REX amplitude was proportional to the stimulus peak amplitude (R2 > 0.98) and the lowest field detection was 1 nT. Furthermore, the detection of QRS-like fields with varying QRS durations yielded significant results in a phantom setup (p < 0.001). REX detection can be transferred to non-sinusoidal pulsed magnetic fields and could provide a non-invasive, quantitative tool for spatially resolved assessment of cardiac biomagnetism. Potential applications include the direct detection and characterization of cardiac conduction.

Electrochemical Applications Reveal Enhanced Photocatalytic Performance of TiO2-Doped ZnS Nanocomposites.

The titanium dioxide (TiO2) nanoparticles were prepared by hydrothermal methods at ambient temperature. Based on XRD analysis, the average crystallite size of pure TiO2 nanoparticles and those doped with ZnS was calculated to be 58 and 54 nm, respectively. At an angle of 25.4°, the prominent peak observed at the (101) plane of TiO2 was confirmed. As can be seen from the collection of peaks, the TiO2 formed has an anatase-type tetragonal crystal structure. A strain of -6.4541 × 10-4 and a grain size of 33 nm can be seen in the W-H plot for TiO2 nanoparticles. For doped ZnS nanoparticles, on the other hand, the values are 1.9448 × 10-4 and 47 nm. In our study, we found that doped nanoparticles were average grain size 134 nm, while pure nanoparticles were average grain size 146 nm. Doping reduces the size of the nanomaterial, which means that the TiO2 molecules form nanoclusters on their surfaces, which can lead to a larger grain size for a pure nanoparticle than for a doped nanoparticle. A wide range of functional groups and their associated bonds were investigated using FTIR spectra in synthesized nanomaterials. TiOTi bonds are subjected to a strong stretching vibration, which is confirmed by the absorption peaks from 450 cm-1 to 800 cm-1. The PL spectra for pure TiO2- and ZnS-doped TiO2 containing nanocomposites of ZnS emit ultraviolet light at wavelengths of 362 and 379 nm in the UV region. Pure and doped samples with optical bandgap energies of ~3.04 and ~3.8 eV corresponding to anatase phases were near ~3.18 eV in Tauc plots. Since the TiO2-doped ZnS heterojunction migrates photoexcited holes toward the interface, while electrons migrate toward the bulk, this results in photoexcited holes migrating toward the interface. To calculate the specific capacitance of the synthesized materials, cyclic voltammetry with pure ZnS and those with ZnS-doped had specific capacitance values of 144.91 F/g and 120.11 F/g, respectively. The catalysts used were ZnS nanocomposite doped with TiO2 in addition to pure TiO2 nanoparticles. The degradation of dye within 80 min after sunlight exposure was monitored with a UV-Vis spectrophotometer at 20-min intervals. ZnS nanoparticles doped with TiO2 display 87.8% greater efficiency than pure nanoparticles. Doped TiO2 nanocomposite degrades at an 87.8% rate, whereas pure TiO2 degrades at ~54%, indicating that the dopants enhance photocatalysis.

Preparation and Luminescence Property Study of Red-Emitting Na3.6Y1.8(PO4)3:Eu3+,Li+/K+ Phosphors with Excellent Thermal Stability for Light-Conversion Application.

A series of red-emitting phosphors, Na3.6Y1.8-x(PO4)3:xEu3+, have been synthesized by a high-temperature solid-phase method. The impact of the partial Li+/K+ ion substitution on the crystal structure and photoluminescence (PL) performance of Na3.6Y1.05(PO4)3:0.75Eu3+ phosphor have been investigated. Various techniques have been used for characterization of the as-obtained materials. X-ray diffraction (XRD) analysis was utilized to confirm the composites of these samples, and the morphology and element distribution were examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). This study found that the developed Na3.6Y1.8-x(PO4)3:xEu3+ phosphors exhibited a prominent emission peak at ~620 nm when excited at 393 nm, which corresponded to 5D0 → 7F2 transitions of Eu3+ ions. Furthermore, the robust emission peak at ~705 nm (5D0 → 7F4) of these phosphors enables a better match with plant pigment absorption. Beyond that, the partial substitution of Li+/K+ ions probably changed the crystal structure, and reduces the symmetry around Eu3+, leading to significantly enhanced luminous intensities by 23.24% and 18.29%, with the highest quantum yields (QYs) reaching 99.85% and 96.29%, respectively. Additionally, the prepared phosphors show non-thermal quenching and superior thermal stability at elevated temperatures from 298 to 473 K. These findings and results suggest that Li⁺/K⁺-substituted Na3.6Y1.05(PO₄)₃:0.75Eu3⁺ phosphors can serve as promising red-emitting phosphors for plant lighting applications.

Coconut Testa Flour Sub-Fractions: Correlation Between FTIR Spectral Data and α-Glucosidase Inhibitory Activities.

Fourier-transform infrared spectroscopy (FTIR) serves as a rapid analytical technique to characterize food specimens chemically. The purpose of this study was to investigate the potential of FTIR combined with multivariate statistics to detect Alpha-glucosidase (Alpha-glu) inhibitory activities of a non-cereal flour-like coconut testa flour (CTF). CTF of five distinct local cultivars was sequentially extracted with hexane, ethyl acetate (EtOAc), and methanol (MeOH) to assay the Alpha-glu inhibitory activity. FTIR spectra of CTF extracts were obtained within the range of 4000-500 cm-1 and the prominent spectral peaks obtained for both hexane and EtOAc extracts were roughly similar but some additional peaks were observed in EtOAc extracts representing phenolic constituents. The major absorbance peaks found in MeOH extracts were primarily indicative of the occurrence of the hydroxyl group associated with carbohydrates and phenolic compounds. The multivariate predictive models developed using partial least squares (PLS) and orthogonal partial least squares (OPLS) regression analyses indicated a strong correlation between Alpha-glu inhibitory activity and spectral data. Models developed for the spectral regions 3700-2800 cm-1 and 1800-500 cm-1 exerted the highest regression coefficients with the lowest root mean square errors. In OPLS regression analysis, the model obtained with third-derivative spectral data was identified as the best, exhibiting the highest regression coefficients and the lowest root mean square errors. Both PLS and OPLS regression analyses indicated a potential correlation of Alpha-glu inhibitory activity with FTIR spectral regions. Notably, OPLS models offered enhanced interpretability of the model parameters. This study suggests that the application of multivariate regression analysis of FTIR spectral data on coconut-based products could help to detect Alpha-glu inhibitory activities.

Enhancing optical properties of Ba-Ni ferrite through nonmagnetic ion doping for sustainable green technologies and renewable energy applications

Barium ferrite powder was produced using a standard ceramic procedure, and its structure and optical properties were investigated. X-ray diffraction analysis (XRD) showed that the powder had a w-type hexagonal structure. The crystallite size was at approximately 35–36 nm, with bulk density and lattice constants increasing as zinc concentration rose. Conversely, X-ray density and porosity decreased with the increasing zinc concentration. This material has useful optical properties, as well as the standard ferrimagnetic properties of barium ferrite, which make it suitable for use in recording media. Ferrimagnetic behavior, which is useful for recording media, occurs because the powder's crystallites have their unit cell axes aligned. Up to the near-infrared part of the spectrum, the powder was found to have a very low absorption coefficient. Both of these properties—an arrangement that gives rise to ferrimagnetism and a corresponding low optical density—make barium ferrite very attractive for high-density recording and microwave applications. Fourier transform infrared spectra of the samples were recorded in the wavenumber range of 400–4000 cm−1 and supported the X-ray diffraction findings by confirming the idea of the formation of W-type hexagonal ferrite by the presence of two prominent peaks at 454 and 591 cm−1 in the FTIR spectra. Zinc addition was also found to enhance the optical properties of the material. The UV–VIS analysis confirms that the band gap energy of Ba-Ni ferrite was indeed reduced by zinc doping. Values decrease from 3.34 eV to 3.20 eV for direct transitions and from 2.96 eV to 2.79 eV for indirect transitions, using Tauc equation. That means that zinc doping enhances the optical properties of Ba ferrite without affecting the hexagonal structure of Ba-Ni ferrite. Moreover, key parameters of optical performance such as the dielectric constant, the extinction coefficient, the penetration depth, and the refractive index show a dramatic increase with a rise in zinc concentration. These attributes make zinc-doped Ba-Ni ferrite a promising optoelectronic material. The material also showed high absorbance in the wavelengths ranging from 334 to 338 nm, which makes it good for the solar cell applications. Overall, zinc-doped Ba-Ni ferrite is a good candidate for sustainable and renewable energy applications. Our study of the optical properties of barium ferrite up to the near-infrared part of the spectrum demonstrated that the powdered material has a very low absorption coefficient. Indeed, the combination of ferrimagnetism and low optical density makes barium ferrite particularly appealing for use in high-density recording and microwave technology applications.

First-principles calculations to investigate Electronic, Optical, Mechanical, and transport characteristics of novel A2BAuCl6 (A = K/Rb/Cs; B = Sc/Y)

By utilizing FP-LAPW, the structure, electronic, optical, mechanical and Transport characteristic of A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) were examined by using DFT. The analysis to the band structure plot of the Halide double perovskites (HDP’s) being studied indicated the existence of indirect band-gaps. The compounds A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) exhibit anisotropic properties, except one compound as seen by their respective shear anisotropy readings of 0.629, 0.532, 1.006, 0.682, 0.803 and 0.977. The materials have inherent ductility, as indicated by their calculated Poisson’s ratios in the range of 0.30 to 0.35. The examined (HDP’s) materials appear to possess indirect band-gaps, as indicated by the band structure plots. The functional inorganic perovskites A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) haven’t similar band-gap values, as determined using the TB-mBJ (modified Becke Johnson) and TB-mBJ + Soc (Spin orbital coupling) assumptions. The visible and ultraviolet domain have prominent peaks, suggesting potential applications of the compounds in solar cells. Moreover, examination of additional optical characteristics such as reflectivity, conductivity, electron energy loss, and absorption coefficients suggest that it possesses the inherent features of a semiconductor. The maximum figure of merit for all the student compounds is above 0.74. The simulated output forms the foundation for A2BAuCl6 (A = K/Rb/Cs, B = Sc/Y) and are of practical importance for multijunction solar cells.

A study of optical properties and electron energy loss spectra of ZnS by linear response theory

The linear response theory has been applied to study the optical properties and electron energy loss spectra of ZnS. The ground state is built using the Full-Potential Linearized Augmented Plane Wave method. Thereafter, the electronic properties such as band structure and density of states are calculated. Calculations of electron energy loss spectra and optical properties are performed on the top of these ground state electronic properties. The calculations are performed using three exchange–correlation kernels namely, adiabatic local density approximation, long range contribution, and the bootstrap. The random phase approximation is also considered. An approach proposed by us to find the material dependent parameter α is used in long range contribution kernel to capture more accurate optical properties. Three values of α viz 0.78, 1.09, and 1.22 are considered. It is observed that the α = 0.78 gives very good results. This proposed scheme is found to work very well for ZnS also. The effect of local field and electron–hole interaction on the spectra is examined. For example after incorporating local field effect the high frequency dielectric constant ε∞ [i.e. ε1E→0eV ], reduces by 9.19, 12.26, 13.51 and 11.02% for random phase approximation, adiabatic local density approximation, long range contribution and bootstrap kernel respectively. In EELS plasmon peak positions are found using the three kernels and random phase approximation. A good accord with experimental results is noted after incorporating local field effects. It is observed that local field effect causes redshift of prominent peak (i.e. plasmon peak) in electron energy loss spectra by 0.61 eV.

Investigation on the structural, optical, photoluminescence, and antimicrobial properties of charged surfactants (CTAB, SDS), and uncharged surfactant (PEG) assisted ZnO/MgO nanocomposites

Different surfactants (CTAB, SDS, and PEG) assisted ZnO/MgO nanocomposites were synthesized by wet chemical route. The hexagonal/cubic system of ZnO/MgO was obtained in the XRD patterns for all synthesized composites.Particle morphologies were tuned in each surfactant in the SEM studies. The synthesized composites related entities were traced by EDX analysis. Narrow band gaps were found in the optical absorption spectra of the composites. Prominent visible emission peaks were detected at 680 nm in all synthesized ZnO/MgO from the PL measurement.The antimicrobial activity of CTAB-assisted ZnO/MgO was analysed against E.coli and S. aureus, and its results were discussed in detail.