UV Properties Research Articles

Visible-light-operative photocatalyst based on Er-TiO2 nanostructures blended with room temperature ferromagnetism, band-gap increment, and high optical transparency

TiO2 thin films doped with Er+3 percentage (1-5 wt%) have been prepared using the sol-gel dip coating technique. Er influences the morphological, structural, magnetic, electrochemical, UV, dielectric, Photoluminescence, and photocatalytic properties of TiO2. FTIR was utilized to examine the different functional groups. The confirmation of the anatase phase formation was established through XRD spectra and FTIR spectra. When the concentration of dopant increased, the crystallite size was found to be decreased from 7.96 to 5.62 nm. A blue shift was noticed in transmission spectra as the dopant concentration increased leading to an increase in the bandgap of thin films. The dielectric properties of all thin films exhibited typical behavior. The barrier height, density of localized states at fermi levels, and hopping distance were examined using AC conductivity measurements. As dopant concentrations increased the dielectric constant increased while AC conductivity decreased. The outcomes of electrochemical charge-discharge tests provided the specific capacitance, power density, and Energy of Er-doped TiO2. Er-doped TiO2 especially at 5 wt% showed significant photocatalytic activity in decomposing indigo carmine under sunlight, suggesting its potential for water treatment, and mitigating environmental pollution. Furthermore, Er-doped TiO2 demonstrated efficient functionality as a CO gas sensor. Er-doped TiO2 exhibited violet photoluminescence, with emission intensity modulated by elevating the Er percentage attributed to heightened defect concentration. These properties find a utility in Optoelectronic device applications. Magnetic analysis indicated that incorporating a trivalent dopant (Er+3) into the Ti-O lattice enhanced ferromagnetic properties.

Studies on the influence of titanium dioxide nanoparticles on thermal, flammability, and UV properties of PEG‐based phase change material composites

AbstractThe current study is focused on the development of phase change material composites (PCCs), attained by the solvent‐casting method, comprising a hydrophilic polymer matrix (polyvinyl alcohol) enclosing polyethylene glycol (PEG600) as an active thermal energy storage (TES) component, and anchored with titanium dioxide nanoparticles (TDN). The impact of the integrated metal oxide nanoparticles at different loadings (0.25%‐1%) on the TES attributes, thermal stability, UV resistance, and flame retardancy of the fabricated composites has been studied. The Fourier‐transform infrared and field‐emission scanning electron microscopy techniques have been used to characterize the PCCs obtained. Phase change attributes and thermal stability of the resultant PCCs are evaluated by differential scanning calorimetry (DSC) and thermogravimatric analysis (TGA). The introduction of TDN particles in different concentrations to the PCCs considerably refines the phase change variables and thermal resistance of the reinforced film samples. PCCs film with 1% TDN concentration exhibited onset melting and crystallization temperatures at −9.9°C and 13.5°C, respectively, and peak melting and crystallization transitions occurred at 8.7°C and 3.6°C, with associated heat enthalpies of 25.57 and 22.22 J g−1, respectively. UV and flame‐retardant (FR) features of the PCCs were found to be improved with the presence of metal oxide particles in the composite films. The metal oxide nanoparticles enhance the FR behavior of fabricated composites by 11.45% as compared to unfilled films.

1991T-like Supernovae* *This paper includes data gathered with the 6.5 m Magellan telescopes at Las Campanas Observatory, Chile.

Understanding the nature of the luminous 1991T-like supernovae (SNe) is of great importance to SN cosmology as they are likely to have been more common in the early Universe. In this paper, we explore the observational properties of 1991T-like SNe to study their relationship to other luminous, slow-declining Type Ia supernovae (SNe Ia). From the spectroscopic and photometric criteria defined in Phillips et al., we identify 17 1991T-like SNe from the literature. Combining these objects with 10 1991T-like SNe from the Carnegie Supernova Project-II, the spectra, light curves, and colors of these events, along with their host galaxy properties, are examined in detail. We conclude that 1991T-like SNe are closely related in essentially all of their UV, optical, and near-infrared properties—as well as their host galaxy parameters—to the slow-declining subset of Branch core-normal SNe and to the intermediate 1999aa-like events, forming a continuum of luminous SNe Ia. The overriding difference between these three subgroups appears to be the extent to which 56Ni mixes into the ejecta, producing the premaximum spectra dominated by Fe iii absorption, the broader UV light curves, and the higher luminosities that characterize the 1991T-like events. Nevertheless, the association of 1991T-like SNe with the rare Type Ia circumstellar material SNe would seem to run counter to this hypothesis, in which case 1991T-like events may form a separate subclass of SNe Ia, possibly arising from single-degenerate progenitor systems.

Optical properties of nanocomposites based on polypropylene modified by nanoparticles of oxide compounds

The optical properties in UV, visible and near IR spectral regions for nanocomposites based on polypropylene modified by nanoparticles of oxide compounds ZrO2, Al2O3, SiO2, MgO, TiO2, ZnO were studied. A shift of the main optical absorption edge to the short-wave region upon modification by dielectric nanoparticles (MgO, ZrO2, and Al2O3) was established. The absorption edge shifts to the long-wave region upon the introduction of semiconductor nanoparticles (ZnO, TiO2) and amorphous SiO2 particles. In all spectra, the absorption bands at 1200, 1400, and 1720 nm characterized by overtone vibrations of CH, CH2, and CH3 molecular groups were recorded. OH groups make a certain contribution to the bands at 1400 and 1720 nm. The dependence of the intensity of these absorption bands on the type and concentration of nanoparticles used in the modification of polypropylene was analyzed. X-ray diffraction analysis of the studied nanocomposites was carried out, the formation of β-PP was registered upon modification by Al2O3 nanoparticles. Photoluminescence spectra of nanocomposites were studied. It was found that the introduction of nanoparticles (except SiO2) does not lead to the formation of new luminescence bands in PP.

Modulation of components toward blue light emission and scintillation properties of Eu2+ activated Sr1-xLaxMgxAl12-xO19 crystal

The development of Eu2+-activated oxide materials with high efficiency, fast decay and narrow bandwidth emission in the visible region is still challenging for the field of luminescence and scintillation applications. Generally, Eu2+ in oxide hosts can emit intense and broad 5d-4f emission in the visible region, but efficient emitting with stable bivalence of Eu is rare in inorganic oxide system. In this work, a series of ASL:Eu2+ (Sr1-xLaxMgxAl12-xO19) powder samples with various La, Mg doping ratios were designed and synthesized to modulate the UV or X-ray excited luminescence properties, including redshift, quantum yield, and decaying lifetime. Moreover, an ASL:Eu2+ crystal with the optimal ratio x = 1/3 was grown, its scintillation performance was compared with standard Bi4Ge3O12 crystal sample and evaluated in detail. These results indicate that the ASL:Eu2+ crystal is potential scintillator as a kind of X-ray detection and provide a reference for the further development of high-performance Eu-activated oxide scintillation materials.

Synthesis and characterization of composite films derived from lemongrass leaves: A valorization approach

Over the past few decades, research into more ecologically friendly packaging materials has significantly increased to reduce non-renewable plastic usage. In this context, biobased films were synthesized from extracted lemongrass leaves. An integrated pretreatment of conventional alkali followed by deep eutectic solvents (DES) was utilized to fractionate the lemongrass leaves into three usable forms, i.e., hemicellulose (HC), lignin (L), and cellulose, which were further utilized in the synthesis of composite films. A total of 4 films have been synthesized, labelled as: Film 1 (CMC HC), Film 2 (L HC), Film 3 (CMC L), and Film 4 (CMC HC L). Film 4 has shown a good water absorption capacity of nearly 65 % and also a higher contact angle of 99.90°, while film 2 has the highest thermal stability among all the films. Film 3 has better UV properties due to the presence of carboxymethyl cellulose (CMC) and lignin. Statement of noveltyIn the present work, composite films have been synthesized from lemongrass leaves for the first time. This is the first report that synthesizes the films from extracted components (CMC, lignin, and hemicellulose) of lemongrass leaves. In this study, all the components were extracted via sequential conventional alkali and DES pretreatment. After extraction, these components were utilized for the composite film synthesis, which is used for various applications of their desirable properties.

Interesting UV and visible photodetection properties of GZO‐based device

AbstractThe aim of this study is to investigate the performance of chemically deposited Ga doped ZnO (GZO) thin film for enhanced UV and visible light detection. Transparent thin film was grown on glass substrates by a spray pyrolysis technique. The Ga doping concentration was maintained at 1 at.% in the solution. The influence of gallium concentration in zinc oxide (ZnO) films on structural, morphological, electrical, and optical properties was studied.Measurements of the photoconductivity were performed by DC electrical tool under visible and UV illuminations. Obtained results reported in this study on the performances of the fabricated GZO based device reveal that the photoresponse, rapidity, photosensivity, responsivity, detectivity, and reproducibility of the device are very interesting in photodetection, especially in UV wavelength domain. We notice that the device has a good responsivity as compared to detectors fabricated using other techniques, with a rather good repeatability. Furthermore, the electronic conductivity mechanism is modeled as an ohmic one.

Lanthanum and Indium intermetallics nanomaterial for thermal photovoltaic applications – A full potential study

In this work Full Potential study performed on Lanthanum compounds to analyze its photovoltaic properties. Five different combinations of Lanthanum and Indium with phosphorus are chosen in this study are La3P, La2InP, LaIn2P, LaP and InP. The optical, structural, thermoelectric, thermal, and electronic properties of all the above-mentioned compounds are analyzed using Density Functional Theory (DFT) applied in the WIEN2k software. Based on the analysis of electronic properties is concluded that La3P, LaP, La2InP and LaIn2P are conductors whereas InP is semiconductor (direct band gap) with band gap (energy) value 0.39 eV. The optical properties analysis shows these materials have desirable properties in the near UV or in the UV region. The low value of Gibbs energy indicates high thermodynamic stability. Power factor values for La2InP, LaP, InP and La3P are found to be in agreement with existing thermoelectric material, rendering them as potential thermal photovoltaic materials.

Terbium(III) oxide as rare earth metal modifier in PbO/Bi2O3 sodium borate glasses for highly efficient optoelectronic devices: Synthesis, characterization, and applications

This paper explores the incorporation of Terbium(III) oxide as a rare earth metal modifier in sodium borate glasses containing PbO/Bi2O3, aiming to enhance the efficiency of optoelectronic devices. The synthesis and characterization of these glasses are detailed, highlighting the unique properties introduced by Terbium(III) oxide. The study investigates the regularities in the characteristics such as physical, XRD, UV, FTIR, and optical properties of 70B2O3–15Na2O – 15PbO – (5-x)Bi2O3 – xTb2O3, where x = 0; 1; 2; 3; 5 mol% prepared glassy samples, considering varying concentrations of bismuth and the modifier (e.g. Tb2O3), and examines their mutual impact on the borate glass matrix involved. It is found that there are sharp peaks on the diffraction pattern, which increase in width and intensity with increasing Terbium concentration from 3 to 5 mol% in the glass matrices, e.g. two-phase structures, amorphous and crystalline, are observed. Moreover, a wide excitation band in the glass matrix is also observed in the region of 200–320 nm. The study delves into the potential applications of these modified glasses in highly efficient optoelectronic devices, contributing valuable insights to the advancement of materials for technological applications.

Highly flexible poly-O-aminothiophenol/intercalated iodide composite with highly morphological properties for green hydrogen generation from Red Sea water

A highly flexible poly-O-amino thiophenol/intercalated iodide (POATP-I) nanocomposite has been successfully synthesized, in a one-step process, as a promising photocathode for H2 production through the Red Sea water. The fabrication of the photocathode involves the oxidation of O-amino thiophenol with iodine, leading to the formation of a remarkably flexible thin film of POATP-I. This thin film exhibits a well-developed network of polymer films. Notably, the nanocomposite demonstrates outstanding light absorbance properties in UV and Vis segments, boasting a calculated bandgap of 2.56 eV. To assess the efficiency of the photocathode, the current density (Jph) generated during the process is employed as a quantitative metric. The Jph values recorded in dark and light range from −0.2 to −1.7 mAcm−2, respectively. This substantial change in Jph highlights the impressive responsiveness of the POATP-I thin film to incident light, facilitating the high-energy electrons formation that contributes to the environmentally friendly hydrogen gas. Furthermore, the thin film exhibits notable responsiveness across various monochromatic photons, from 340 to 730 nm. Optimal performance is observed at 340 nm, where Jph reaches −0.45 mA.cm−2. Additionally, the estimated hydrogen production rate is calculated at 0.15 mmol h−1 for every 10 cm2 of the material’s surface. These remarkable characteristics position the material for potential industrial applications in hydrogen gas production, providing a sustainable and environmentally friendly solution for hydrogen production.

Investigation of photoluminescence and thermoluminescence properties of UV& γ irradiated Li4SrCa(SiO4)2:Dy3+ phosphor

Investigation of photoluminescence and thermoluminescence properties of UV& γ irradiated Li4SrCa(SiO4)2:Dy3+ phosphor

Radiation resistance of polypropylene modified with nanoparticles of oxide compounds

The results of studies of optical properties in UV, visible and IR spectral regions, and radiation resistance of nanocomposites based on polypropylene modified with nanoparticles of oxide compounds (ZrO2, Al2O3, SiO2, MgO, TiO2, ZnO) are presented. Diffuse reflectance spectra were recorded under 2 ∙ 10−6 torr vacuum before and after electron irradiation (in situ, Е = 30 keV, F = 2 ∙ 1016 cm−2). According to research findings, modification of polypropylene with nanoparticles leads to an increase in radiation resistance, which depends on the structure of the nanopowders, their size and specific surface area. The SiO2 nanopowder, characterized by its amorphous nature, the largest specific surface area, and the smallest particle size, stands as the most effective modifier for enhancing radiation resistance. The IR-Fourier spectra of electron-irradiated samples are similar to the original spectra. A slight decrease in transmission across all characteristic bands compared to the non-irradiated samples indicates minor structural changes as a result of irradiation.

The Missing Symbiotic Stars: A Joint Analysis with Gaia, GALEX, and XMM-Newton Data

The existence of a population of low-accretion-rate symbiotic stars (SySts), consisting of a giant star and a compact companion (usually a white dwarf), has been proposed recently. However, their population has not been fully understood. In this work, we present an investigation on SySts candidates consisting of asymptotic giant branch stars (AGBs) by cross-correlating the Gaia DR3, the Galaxy Evolution Explorer All-Sky Imaging Survey, and the 4XMM DR13 catalogs. We first build a sample of AGBs within 500 pc based on their locations in the Gaia color–absolute magnitude diagram. We then explore the UV and X-ray properties of the sampled AGBs and compare them to known SySts and candidates. We find 10 SySts candidates based on the far-ultraviolet excess. The typical UV luminosity of the candidates is 1031 erg s−1, which corresponds to a typical accretion rate of 10−12–10−11 M ⊙ yr−1, which is more than 1 order of magnitude lower than known SySts. Based on these findings, the total number of SySts within 500 pc is estimated to be 18. The number of AGBs with X-ray flux above 10−14 erg s−1 cm−2 within 500 pc is estimated to be 37. Our finding implies that a large number of low-accretion-rate SySts are yet to be detected, which provides a base for a complete understanding of their population.

ANNEALING EFFECT ON UV DETECTION PROPERTIES OF ZnO:Al STRUCTURES

The aim of this study was to develop low-powered, highly selective UV sensor to continuously monitor personalized UV exposure as well as to study annealing effect on UV detection properties of the sensors. ZnO:Al structures were obtained by chemical growth method followed by thermal annealing at 625 °C for 2 h. The studied samples exhibit maximal UV response of 620/488 at 25 °C/50 °C to 370 nm UV radiation before/after annealing, respectively. Thermal annealing of sensor (250 °C for 1 h) led to improvement in fall time from 3860 seconds to 262 seconds at 25 °C and highest responsivity (~48 mA/W) came out for 370 nm wavelength at 75 °C operating temperatures. Consequently, excellent selectivity for 370 nm UV illumination can be ascribed as due to thermal annealing effect which increases the crystallinity, grain size, and roughness of the sensing film. The PL measurements reveals the suppression of structural defects, increase in intensity after annealing and enhanced UV response due to presence of Al content in films. Overall, these structures showed magnificent UV properties, before and especially after additional thermal annealing. UV sensing mechanism of such nanomaterial-based sensor were explained with physio-chemical processes take place on the surface of these structures. The obtained results on annealed ZnO:Al films-based devices is superior to reported performances of other nanostructures, proving new results for UV sensing applications at different operating temperatures in various fields.

Sustainable food packaging: Harnessing biowaste of Terminalia catappa L. for chitosan-based biodegradable active films for shrimp storage

Shrimp, a globally consumed perishable food, faces rapid deterioration during storage and marketing, causing nutritional and economic losses. With a rising environmental consciousness regarding conventional plastic packaging, consumers seek sustainable options. Utilizing natural waste resources for packaging films strengthens the food industry. In this context, we aim to create chitosan-based active films by incorporating Terminalia catappa L. leaves extract (TCE) to enhance barrier properties and extend shrimp shelf life under refrigeration. Incorporation of TCE improves mechanical, microstructural, UV, and moisture barrier properties of the chitosan film due to cross-linking interactions, resulting in robust, foldable packaging film. Active TCE film exhibits high antioxidant property due to polyphenols. These films also exhibited low wettability and showed hydrophobicity than neat CH films which is essential for meat packaging. These biodegradable films offer an eco-friendly end-of-life option when buried in soil. TCE-loaded films effectively control spoilage organisms, prevent biochemical spoilage, and maintain shrimp freshness compared to neat CH films during refrigerated condition. The active TCE film retains sensory attributes better than neat chitosan, aligning with consumer preference. The developed edible and active film from waste sources might offer sustainable, alternative packaging material with a lower carbon footprint than petroleum-based sources.

An experimental study on mechanical properties of UV cured 3D nanofibre printing materials

An experimental study on mechanical properties of UV cured 3D nanofibre printing materials

An experimental study on mechanical properties of UV cured 3D nanofibre printing materials

An experimental study on mechanical properties of UV cured 3D nanofibre printing materials

Bootstrapping the chiral anomaly at large Nc

The bootstrap approach (demanding consistency conditions to scattering amplitudes) has shown to be quite powerful to tightly constrain gauge theories at large Nc. We extend previous analysis to scattering amplitudes involving pions and external gauge bosons. These amplitudes allow us to access the chiral anomaly and connect low-energy physical quantities to UV properties of the theory. In particular, we are able to obtain an analytic bound on the chiral anomaly coefficient as a function of the pion dipole polarizabilities. This bound can be useful for holographic models whose dual UV completions are not known, and provide a consistency condition to lattice simulations.

Large scalable, anti-ultraviolet, strong cellulose film with well-defined dual-pores for longtime daytime radiative cooling

Passive daytime radiative cooling technology, which reflects sunlight and emits thermal radiation simultaneously, shows great potential in releasing global warming and energy consumption. Particularly, cellulosic cooling materials, with the advantages of high infrared emissivity, eco-friendly, and easy processing, have gained great attention. However, the poor solar reflectance and the poor durability related to UV and mechanical properties still limited its broad applications. In this work, we developed a novel cellulose composite film (CCF) with a well-defined, hierarchical micro/nanostructure via a rational solvent-induced phase separation technology for efficient and longtime daytime radiative cooling. TiO2@PT synthesized via facile ball milling process was used to serve as a dual functional modifier, which can improve the optical, mechanical properties, and anti-UV function of the cellulose-based daytime radiative cooler. Benefiting from the hierarchical dual pores, formed tough interface, and assembled anti-UV functional network, the as-prepared CCF displayed ultrahigh solar reflectance of 97.6 % and enhanced Young's modulus and tensile strength increase by 13 and 4.4 times, respectively. Most importantly, the solar reflectance of CCF is maintained constant after continuous UV tests for 720 h. The work provides a general strategy to simultaneously enhance both the mechanical stability and the UV durability of polymer-based PDRC materials toward large-scale applications.

Sustainable green composite of yam and agricultural waste corn stalk fiber with good mechanical, thermal, optical, aging performance and excellent biodegradability

Sustainable green composites with safe biodegradability produced using environmentally benign materials are required as modern-day alternatives for harmful synthetic materials. Agricultural waste such as corn stalks and underutilized natural polymer sources such as yam are significant potential candidates in this regard. In our work, a green composite of yam and alkali-treated corn stalk fiber was prepared through a simple solution casting and oven-drying method. The successfully prepared green composites displayed good mechanical and thermal properties as the corn stalk fibers effectively reinforced the yam bioplastic matrix. Spectral studies such as FTIR, SEM, and p-XRD confirmed the probable structural changes and formation of the composites. Prepared green composites possessed high resistance and good thermal (−2 °C and 70 °C), UV (254 nm for 180 hours), and chemical aging properties along with low moisture absorption behavior. Further, the green composites showed excellent biodegradable nature under normal environmental conditions. Thus, potentially capable green composite for applications in packaging, biomedical, automobile, and construction sectors was reported here.