Decrease In Refractive Index Research Articles

Core-shell nanomaterials based on La2FeCrO6 coated with metal oxides for optical applications

In this research work, the preparation of core/shell nanoparticles comprising La2FeCrO6 (LFCO) as the core was accompanied by the choice of ZnO and CuO as different shells. Structural and optical characteristics were investigated for the LFCO (core) relative to La2FeCrO6/ZnO and La2FeCrO6/CuO core/shell NPs. x-ray diffraction analyses reveal the conformation of core/shell structures within average crystallite sizes of 22.46 nm and 25.03 nm. Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) were performed to provide fundamental information about the vibrational modes and the functional groups of core/shell NPs, respectively. x-ray photoelectron spectroscopy (XPS) detects the electronic states of the constituent elements of the core/shell nanostructures, including lanthanum, iron, chromium, oxygen, zinc, and copper. Optical characteristics have been extensively analyzed using UV spectroscopy. The energy gap (Eg) was determined by utilizing both Tauc and Derivation of Absorbance Spectrum Fitting (DASF) methods. LFCO/ZnO and LFCO/CuO core/shell NPs exhibit a direct optical transition, similar to that of the core LFCO NPs, with a decrease in band gap value from 3.4 eV for the core to 3.3 eV and 3.18 eV for LFCO/ZnO and LFCO/CuO core/shell NPs respectively. The enhanced transparency of core/shell NPs, particularly at longer wavelengths, is evident from the decrease in refractive index (n) compared to that of the core (LFCO) NPs. This decrease is attributed to the encapsulation of LFCO with either ZnO or CuO NPs. The samples exhibit a decline in both linear and non-linear optical susceptibilities with respect to the square of photon energy. The LFCO/CuO sample shows excellent results in the photocatalytic degradation of aqueous organic dyes, considering it a promising candidate for wastewater treatment and the removal of organic pollutants.

Composition, Temperature, and Size Regulation of Refractive Index in Ternary Group-Ⅲ Nitride Alloys: a Bond Relaxation Investigation

Abstract The physical origins of composition-, temperature-, and size-motivated changes in refractive index in crystals have long been a puzzle. Combining the bond-order-length-strength theory, local bond average approach, and core-shell structural model, we investigated the refractive indexes in dependencies of composition, temperature, and size for the ternary wurtzite group-Ⅲ nitride alloys. The theoretical reproduction of the observations disclosed that (ⅰ) the doping of small atoms caused the contraction in bond length, the strengthening in bond energy, and the decrease of refractive index, whereas the doping of large atoms led to an elongation of bond length, a weakening of bond energy, and an increase of refractive index; (ⅱ) the refractive index is inversely proportional to the cohesive energy and the cube of the Debye temperature; and (ⅲ) with the gradual decrease in solid size, the coordination number lowers, the bond length contracts, the bond energy gains, the surface-to-volume ratio rises, and the refractive index decreases. The proposed formulation not only shows an in-depth comprehension of the physical essence of the stimuli impact on the refractive index but also is expected to be conducive to the exploitation, optimization, and operation of the new-type photonic, piezoelectric, and pyroelectric nanometer devices for the ternary wurtzite alloys.

Using femtosecond laser pulses to investigate the thickness-dependent nonlinear optical properties of nickel oxide thin films and their potential use as optical limiters

In this study, the Z-scan technique was used to investigate the nonlinear optical properties of nickel oxide (NiO) thin films of various thicknesses. Direct current (DC) sputtering was used to deposit single-phase NiO thin films with thicknesses of 280, 350, and 470 nm onto a soda-lime glass substrate. The film structure was measured using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the linear optical properties were measured using a UV-Vis spectrophotometer. NiO thin films were irradiated with 100 fs laser pulses at various excitation wavelengths and excitation powers to determine the nonlinear absorption coefficient and nonlinear refractive index. The NiO films were found to have reverse saturable absorption and self-focusing behavior. As the thickness of the NiO film increases, both the nonlinear absorption coefficient and nonlinear refractive index decrease. Additionally, the investigation of the optical limitations of NiO thin films revealed a definite association with the thickness of the NiO thin film.

Study on physicochemical properties of hydroxyl-functionalized ionic liquids

A thorough understanding of the physicochemical properties of ionic liquids (ILs) is significant for the design and synthesis of the desired ILs. In this study, three hydroxyl-functionalized ILs were designed and synthesized, and their density, viscosity, surface tension and refractive index were measured in the temperature range of 293.15–333.15 K, and it was found that they all decreased with the increase of temperature. By using the measured physicochemical property data and the corresponding empirical equations, the molecular volumes of the three ILs were calculated and the contribution of one (CH2-) group to the molecular volume was found to be 0.0262 nm3. The viscous flow activation properties were discussed and ΔH≠ > ΔS≠T was found for the three ILs, indicating that enthalpy effect is the main source of viscous flow resistance. Surface energy and surface entropy were calculated, and it was found that surface entropy is the main factor determining surface properties. The free volume was calculated, and it was found to increase with temperature, which could provide more space for light to pass through the medium, leading to a decrease in refractive index with temperature. Simultaneously, the influence of cation and anion structures on the properties of the ILs was also discussed.

Physicochemical properties of binary mixtures of cation-fluorinated ionic liquids with their non-fluorinated analogues

This work reports an investigation of the physicochemical properties (density, viscosity, refractive index and thermal stability) of four binary mixtures having a common acetate ([OAc]¯), trifluoromethanesulfonate ([OTf]¯) or bis(trifluoromethylsulfonyl)imide ([NTf2]¯) anion with either cation-fluorinated and non-fluorinated methylimidazolium (MIm) or pyridinium (Py) cations respectively, at various temperatures. The mixing behaviour of the binary mixtures was analysed by 1H and 19F Nuclear magnetic resonance (NMR) spectrometry, and the excess properties of the mixtures were calculated from the physicochemical data. The binary mixtures of fluorinated ionic liquids (FILs) with their non-fluorinated or alkyl-substituted analogues (AILs) showed an increase in density and viscosity but a decrease in refractive index with an increase in mole fraction of the pure FILs. The thermal stability of the AILs was higher than the FILs, however, an increase in the mole fraction of the pure FILs in the binary mixtures made a negligible impact on the thermal stability of the binary mixtures. These binary mixtures were found to deviate from ideal behaviour for the different physicochemical properties tending to vary between the extremes of the pure components. The large differences in properties of FILs compared with their non-fluorinated analogues were shown to be associated with the size of the fluorine atoms in the fluoro-alkyl chain, the tendency of the fluoro-alkyl chain to form aggregates with fluorinated anions, and the hydrogen bond acceptor strength of the anions. The excess properties were fitted to the Redlich-Kister polynomial equation, and no significant deviation was obtained. This study shows that the physicochemical properties of the fluorinated ionic liquids can conveniently be adjusted for specific applications by simply varying the amount of the cation-fluorinated component in binary mixtures.

Effects of isotropic stress on the band structure elastic, optical, thermal, and x-ray diffraction properties of TiSnO3.

Cubic perovskite titanium stannous oxide (TiSnO3) is a promising material for various applications due to its functional properties. However, understanding how these properties change under external stress is crucial for its development and optimization. This study employed density functional theory calculations to investigate the structural, electronic, optical, thermal, and mechanical properties of TiSnO3 under varying degrees of external static isotropic stress (0-120 GPa). The study reveals a significant decrease in the bandgap of TiSnO3 with increasing stress due to lattice modifications and the formation of delocalized electrons. Partial density of states analysis indicates that Sn and O states play a key role in shaping the electronic band structure. TiSnO3 exhibits increased light absorption with stress, accompanied by a blue shift in absorption peaks, whereas, both polarizability and refractive index decrease with increasing stress. Mechanically, all elastic moduli (bulk, shear, and Young's) show an increase under stress, signifying a stiffening response of the material under stress. Similarly, the Pugh ratio suggests a transition from ductile to brittle behaviour at elevated stress levels. Phonon dispersion calculations indicate the instability of the cubic phase at 0 K. However, a phonon gap emerges at 30 GPa and widens with increasing stress. X-ray diffraction further supports these findings by demonstrating a shift in diffraction peaks towards higher angles with increasing stress, consistent with the applied stress. In conclusion, this computational study offers a thorough understanding of how external stress influences the properties of TiSnO3, providing valuable insights for potential applications in various fields.

The efficacy of the food-grade antimicrobial xanthorrhizol against Staphylococcus aureus is associated with McsL channel expression.

The emergence and spread of multidrug-resistant Staphylococcus aureus strains demonstrates the urgent need for new antimicrobials. Xanthorrhizol, a plant-derived sesquiterpenoid compound, has a rapid killing effect on methicillin-susceptible strains and methicillin-resistant strains of S. aureus achieving the complete killing of staphylococcal cells within 2 min using 64 μg/mL xanthorrhizol. However, the mechanism of its action is not yet fully understood. The S. aureus cells treated with xanthorrhizol were studied using optical diffraction tomography. Activity of xanthorrhizol against the wild-type and mscL null mutant of S. aureus ATCC 29213 strain was evaluated in the time-kill assay. Molecular docking was conducted to predict the binding of xanthorrhizol to the SaMscL protein. Xanthorrhizol treatment of S. aureus cells revealed a decrease in cell volume, dry weight, and refractive index (RI), indicating efflux of the cell cytoplasm, which is consistent with the spontaneous activation of the mechanosensitive MscL channel. S. aureus ATCC 29213ΔmscL was significantly more resistant to xanthorrhizol than was the wild-type strain. Xanthorrhizol had an enhanced inhibitory effect on the growth and viability of exponentially growing S. aureus ATCC 29213ΔmscL cells overexpressing the SaMscL protein and led to a noticeable decrease in their viability in the stationary growth phase. The amino acid residues F5, V14, M23, A79, and V84 were predicted to be the residues of the binding pocket for xanthorrhizol. We also showed that xanthorrhizol increased the efflux of solutes such as K+ and glutamate from S. aureus ATCC 29213ΔmscL cells overexpressing SaMscL. Xanthorrhizol enhanced the antibacterial activity of the antibiotic dihydrostreptomycin, which targets the MscL protein. Our findings indicate that xanthorrhizol targets the SaMscL protein in S. aureus cells and may have important implications for the development of a safe antimicrobial agent.

Identifying orientation-dependent optical properties of single-crystalline β-Ga2O3 films

We explore the effect of crystallographic anisotropy on the optical properties of high-quality β-Ga2O3 thin films by conducting experimental measurements and theoretical simulations. High resolution x-ray diffraction measurements confirm the high-quality and the single crystalline quality, ruling out the effect of defects for all films. Raman spectra reveal the presence of anisotropy, as evident from a stronger Bg(2) mode related to GaIO4 chain libration in (100) orientation. Conversely, a stronger Ag(10) mode corresponding to tetrahedral bonds is evident in the (010) orientation, while it is suppressed in the (100) orientation. Low-temperature photoluminescence spectra indicate the presence of intrinsic impurity-related emissions in the ultraviolet and blue regions for all films. An anisotropic bandgap is observed, wherein the lowest bandgap value is related to the (010) oriented sample. Spectroscopic ellipsometry measurements confirm different refractive indices and extinction coefficient values depending on crystallographic orientation, which are in good agreement with the theoretical values obtained by density functional theory, confirming the anisotropic characteristics. The theoretical calculations of charge density show that the strength of covalent bonding depends on the β-Ga2O3 orientation, while experimental findings demonstrate that as the covalent bonding character increases, the film bandgap and the refractive index decrease. The anisotropy of β-Ga2O3 with respect to the crystal orientation leads to variations in the extinction coefficient, refractive index, and bandgap energy.

The effect of hydrostatic pressure, temperature and impurity factor on linear and nonlinear optical properties of InxGa1-xAs tuned quantum dot with modified Gaussian potential under the action of a vertical magnetic field

This study presents a detailed theoretical analysis of the effects of hydrostatic pressure, temperature, impurity factors, and external electric fields on the optical properties of InxGa1-xAs tuned quantum dot. A uniform magnetic field, directed perpendicular to the quantum dot plane, is applied. The system is excited using a monochromatic electromagnetic field, considering electron intersubband transitions. Energy levels and wave functions are determined using the parabolic band approximation and effective mass approximation. The linear and nonlinear optical absorption coefficients and refractive index changes are computed using the compact-density matrix approach and the iterative method. Numerical results indicate that the peaks of the linear and nonlinear optical absorption coefficients and refractive index changes shift towards lower energies (red shift) and higher energies (blue shift) under varying hydrostatic pressure, temperature, and impurity factor strength. Additionally, the peak values of the absorption coefficients and refractive index changes increase or decrease based on these parameter variations. These results have significant implications for the design and optimization of quantum dot-based optoelectronic devices.

Suppressed terahertz dynamics of water confined in nanometer gaps.

Nanoconfined waters exhibit low static permittivity mainly due to interfacial effects that span about one nanometer. The characteristic length scale may be much longer in the terahertz (THz) regime where long-range collective dynamics occur; however, the THz dynamics have been largely unexplored because of the lack of a robust platform. Here, we use metallic loop nanogaps to sharply enhance light-matter interactions and precisely measure real and imaginary THz refractive indices of nanoconfined water at gap widths ranging from 2 to 20 nanometers, spanning mostly interfacial waters all the way to quasi-bulk waters. We find that, in addition to the well-known interfacial effect, the confinement effect also contributes substantially to the decrease in the complex refractive indices of the nanoconfined water by cutting off low-energy vibrational modes, even at gap widths as large as 10 nanometers. Our findings provide valuable insights into the collective dynamics of water molecules which is crucial to understanding water-mediated processes.

On‐Chip Optical Power Limiter for Quantum Communications

AbstractThis article presents an on‐chip optical power limiter that utilizes the thermo‐optical defocusing effect. A pair of input and output waveguides is designed to mimic emitting and receiving antennas. The waveguides are separated by a free‐space region filled with poly‐methyl‐meth‐acrylate (PMMA) material, which has a negative thermal‐optic coefficient that causes a decrease in refractive index with an increase in temperature. As the power in the input waveguide increases, the refractive index of the free‐space region decreases, which in turn increases the radiated beam's divergence angle with respect to input power. The empirical findings demonstrate that the non‐linear divergence angle can be written as , where θ0 represents the divergence angle of the equivalent Gaussian beam, k is a waveguide‐specific constant, and P is the input power. The edge of the receiving waveguide is tapered to adjust the coupling of the divergent beam to the output waveguide. The taper width is optimized to minimize insertion loss. The devices are two orders lengthwise smaller compared to the bulk demonstration, and they exhibit low loss ranging from 0.2 to 10 dB.

First-principles study of Cs/O deposited Na<sub>2</sub>KSb photocathode surface

Na<sub>2</sub>KSb photocathodes have many applications in vacuum optoelectronic devices, such as photomultiplier tubes, image intensifiers, and streak image tubes for high-speed detection and imaging in extremely weak light environments, due to their advantages of high temperature resistance, small dark current, low vacuum requirement, low fabrication cost and high fabrication flexibility. In addition, this type of photocathode has important application prospect in high brightness accelerator photoinjectors. To guide the fabrication of high-sensitivity Na<sub>2</sub>KSb photocathodes, Na<sub>2</sub>KSb surfaces with different surface orientations and atom terminations are investigated by the first-principles calculation method based on the density functional theory to obtain the most stable and most favorable surface for electron emission. From the perspectives of surface energy, adsorption energy, and work function before and after Cs adsorption, it is revealed that the Na<sub>2</sub>KSb (111) K surface exhibits superior surface stability and electron emission capability. Furthermore, the electronic structure and optical properties of Cs adsorption and Cs/O co-adsorption on the Na<sub>2</sub>KSb (111) K surface under different Cs coverages are analyzed, and the mechanism of Cs/O deposition on Na<sub>2</sub>KSb surface is studied. The adsorption energy of Cs in the Cs/O adsorption model is much larger than that in the single Cs adsorption model, indicating that the adsorption of O atoms on the Na<sub>2</sub>KSb surface can make the adsorption of Cs atoms on the surface stronger, and thus increasing the adhesion of Cs atoms on the surface. After adsorption of Cs on the Na<sub>2</sub>KSb (111)K surface, the surface work function only decreases by 0.02 eV, while the maximum work function decrease for the Cs/O adsorbed surface is 0.16 eV, with the Cs coverage of 2/4 ML and the O coverage of 1/4 ML. The adsorption of Cs/O atoms on the surface facilitates the charge transfer above the surface and results in charge accumulation, which can form the effective surface dipole moment. The magnitude of the surface dipole moment is directly related to the change of work function. Furthermore, through the analysis of the electronic band structure and density of states, it is found that the adsorbed Cs atoms have additional contribution to the band structure near the conduction band minimum. After the introduction of O atoms, the valence band moves up, also the bottom of the conduction band and the top of the valence band become flat. The Cs/O deposition is beneficial to increasing the absorption of near-infrared light on the Na<sub>2</sub>KSb surface, but it will reduce the absorption of ultraviolet light and visible light, and the refractive index will also decrease. This work has a certain reference significance for understanding the optimal emission surface of Na<sub>2</sub>KSb photocathode and the mechanism of surface Cs/O deposition.

Electrochemical synthesis of a novel hybrid nanocomposite based on Co3O4 nanoparticles embedded in PANI- camphor sulfonic Acid matrix for optoelectronic applications

In this study, we report on the preparation and characterization of Co3O4 nanoparticles (NPs) embedded in polyaniline-Camphor Sulfonic Acid (PANI-CSA) polymer matrix via electrochemical polymerization method. Developing conductive organic films with tunable optical properties are crucial for many novel optoelectronic applications. Thus, incorporation of metallic oxide nanoparticles (Co3O4 NPs) into polymer matrix (PANI-CSA) represents an alternative approach to address these desired features. As a result of careful optimization of several growth conditions, PANI-CSA/Co3O4 hybrid nanocomposites with high crystalline and homogeneous structures were successfully synthesized on ITO substrates. The impact of Co3O4 NPs concentrations on the structural and optical properties has been extensively investigated. A variety of structural and optical techniques, including FTIR, UV-VIS spectroscopy, and XRD, were employed to characterize the prepared hybrid nanocomposites. The initial findings and analysis reveal that the integration of Co3O4 NPs into PANI-CSA matrix have a trifunctional role in reducing π-polaron and Urbach energies (EU) whereas increasing π-π* band gaps. A further increase in NPs concentration up to 12 wt % results in continuous increase in the absorbance bands and absorption coefficients, indicating improved optical properties as compared to the control sample (PANI-CSA without NPs). The observed redshifts in absorbance band positions are attributed to narrowing of the optical band gap caused by interactions between PANI-CSA chains and Co3O4 NPs. FTIR spectra confirmed the exact chemical composition of PANI-CSA/Co3O4 nanocomposites, exhibiting broadened and less intense peaks compared to the control sample, indicating their interaction at the molecular levels. Additionally, XRD measurements indicate that no peaks of other phases were detected in all nanocomposites, demonstrating their purity and crystallinity. Finally, A single oscillator model by Wemple-DiDomenico (WDD) coupled with a Sellmeier dispersion relation based on one term has been utilized to model the typical electronic transition excitation energies, dispersion energies, optical conductivities, and many other optical desperation parameters for PANI-CSA and PANI-CSA/Co3O4 at various concentrations. For instance, in response to increased NPs content, linear optical susceptibility, third-order nonlinear optical susceptibility, and nonlinear refractive index decrease. In contrast, the ratio of free carriers to effective mass (N/m) increased from 4.73 × 1039 to 4.91 × 1039 m−3 kg−1 with increasing NPs concentration. Based on the observed results, these hybrid nanocomposites possess improved properties, indicating their potential use as active materials in a variety of novel optoelectronic applications.

The Refractive Index Sensing Performance of Au and Ag Nanoparticles Under Different Surrounding Environment

AbstractBenefiting from the sensitive response to the change of surrounding environment, localized surface plasmon resonance sensors have wide applications for the detection of bio‐/chemical species. Traditionally, the sensitivity research of localized surface plasmon resonance sensors mainly focused on the morphologies and materials of sensor structures. Instead, the effect of environmental refractive index on sensitivity of a gold (Au) nanoparticle sensor is theoretically investigated in this work. The results show that when few free targets are adjacent to the sensor, a better sensing performance can be achieved as the refractive index increases from 1.00 to 1.10. However, when a target layer is closely covered on the Au nanoparticle, a 0.1 decrease in environmental refractive index can lead to a significant improvement in sensitivity. The similar results can be also obtained on a silver (Ag) nanoparticle. This work provides new understandings for advanced sensing applications of surface plasmon resonance sensors.

Optimization of NiFe oxygen evolution reaction catalytic electrode based on characterization of onset potential distribution

Lower onset potential and uniform distribution of catalytic performance are crucial for catalytic electrodes. This study presents a method for characterizing the spatial distribution of the initial potential on the surface of the oxygen evolution reaction (OER) catalytic electrode using total internal reflection imaging (TIRi). By applying linear sweep voltammetry (LSV) with incremental positive potential to the electrode, the surface of the electrode generates micro-to-nanometer-sized O2 bubbles during the initial phase of OER, resulting in an increase in light intensity and a decrease in the effective refractive index (RI). By establishing the relationship between light intensity and potential, the spatial distribution of the OER onset potential can be quantified, enabling direct visualization of the electrode's surface and its catalytic activity. Furthermore, we applied the TIRi method to assess the influence of different substrates and electrodeposition conditions on the catalytic activity, repeatability, and durability of NiFe catalytic electrodes. This research contributes to the evaluation of various electrode deposition methods for large-scale catalytic electrodes and the rational manufacturing of efficient OER electrodes in industrial energy devices, promoting the development of the hydrogen energy field.

Studying the optoelectronic properties and emission quenching dynamics of poly‐TPD by incorporating ZnO nanoparticles and multiwalled carbon nanotubes

AbstractIn this study, the optoelectronic properties and emission dynamic quenching of poly‐TPD were investigated upon incorporating ZnO nanoparticles and multiwalled carbon nanotubes (MWCNTs). A solution blending method was utilized to successfully prepare poly‐TPD incorporated with various contents of ZnO/MWCNT nanocomposites. The optoelectronic properties of the nanocomposites were analyzed using UV–Vis and photoluminescence spectrophotometry. The incorporation of the nanocomposites resulted in a decrease in transmittance, reflectance, and absorption edge, indicating a reduction in the poly‐TPD's bandgap. Parameters such as extinction coefficient, Urbach energy, and charge carrier density also decreased with addition of the nanocomposites, suggesting increased scattering, disorder, and the presence of defect states. The decrease in bandgap from 2.970 to 2.852 eV with increasing the nanocomposite content confirmed the emergence of new electronic states. Furthermore, the nature of the transitions changed from direct allowed for pure poly‐TPD to direct forbidden upon incorporation of the nanocomposites. The inclusion of the nanocomposites also led to a decrease in refractive index and fluorescence intensity. The observed fluorescence quenching primarily exhibited dynamic characteristics, with a Stern–Volmer constant of 5.14 L/g and quenching rate constants surpassing the minimum threshold for efficient quenching. The increase in charge transfer rate constants with the nanocomposite content indicated enhanced quenching efficiency and charge transfer, likely due to the increased surface area and presence of defects. These findings suggest that poly‐TPD incorporated with ZnO/MWCNT nanocomposites displays promising properties for applications in optoelectronic devices.

Study on the Physical, Optical and Luminescence Properties of the Cr-Doped Recycled Waste Glass

The rapid economic growth in recent years has led to the use of glass material in many activities, resulting in a large amount of glass waste. The efficient use of waste glass recycling has gained increasing attention. Researchers propose a method for recycling waste glass to reduce glass manufacturing costs and investigate the physical, optical, and luminescence properties of chromium oxide-doped glass with the stoichiometry of (35-x) B2O3: 35SiO2 (use waste glass as SiO2): 12Na2O: 7.9CaO: 0.1Sb2O3: 10BaO: xCr2O3 when x = 0.00 to 0.05 mol%. Glass was synthesized using the melt quenching at 1,200 degrees Celsius for 3 h. Archimedes’ principle and the Abbe refractometer were used to calculating density and refractive index decrease with the addition of 0.01 mol% of Cr3+ concentration. At room temperature, absorption spectra were analyzed using a UV-VIS-NIR spectrometer exhibiting two broadband at 438 and 625 nm intense bands, and the luminescence properties of the Cr3+ glasses system were investigated using an excitation wavelength of 567 nm, with luminescence peaks observed around 750 nm. CIE L* a* b* shows the green color.

High transparency of PbO–BaO–Fe2O3–SrO–B2O3 glasses with improved radiation shielding properties

This study investigated the role of PbO and BaO on the optical and radiation shielding properties of PbO–Fe2O3–SrO–B2O3–BaO glass systems. Optical studies indicate that the prepared glass samples are transparent within the visible spectrum; the transparency increases marginally with increasing PbO/BaO concentrations. Furthermore, by increasing the PbO/BaO ratio, the BO4 units increase (BO3 units decrease), and the density values increase. In addition, the optical band gaps widen, and linear and nonlinear refractive indices decrease. The reductions in nonbridging oxygen were responsible for the increased band gaps and decreased refractive index behavior. Moreover, the ionizing radiation shielding studies showed improved behavior with additional PbO additives. Also, the HVL values of the present glass samples are comparatively lower than the HVL of some standard ionizing radiation shielding materials. Finally, the combination of effective radiation shielding properties and high transparency makes the current glass samples good candidates in the ionizing radiation shielding field.

Switchable whispering gallery mode lasing via phase transition.

Combining phase-transition materials with optical microcavities may advance the applications of whispering-gallery mode (WGM) lasing in performance customization, sensing, and optical switching. In this study, switchable WGM lasing based on phase transition is reported. The device is designed by introducing the phase-transition hydrogel into the capillary microcavity. After approaching the phase-transition point in hydrogel, the number of WGM lasing modes decreases sharply with a significant blueshift in the wavelength. The phenomenon is caused by the increase in light scattering and decrease in effective refractive index of the device. Furthermore, single-mode lasing is obtained by manipulating the phase transition, which exhibits superior reversibility. This study may pave the way for designing and multifunctioning of novel WGM lasing in photonic devices.

Promising reddish-orange light as Eu3+ incorporated in zinc-borosilicate glass derived from the waste glass bottle

Eu3+ incorporated zinc-borosilicate glass was synthesized using melt-quenching method. XRD and FTIR verified the amorphous nature of the samples. The absorption spectra indicate the Eu3+ ions in the UV-visible region at ∼394 nm. The direct and indirect band gap decrease from 5.152 eV to 5.082 eV and 4.133 eV to 3.837 eV, respectively. Meanwhile, the refractive index decrease from 2.145 to 2.202, while the Urbach energy ranges from 0.682 eV to 0.733 eV. All the samples have a good transmission percentage at 70–75%. Under the excitation of 400 nm, the intensity of the PL spectra increased when the Eu3+ dopant increased. The optimum content for Eu3+ incorporated ZnO–B2O3–GB glass is 3 wt.% among the other Eu3+ content (0, 1, and 2 wt.%) in this work. The reddish-orange emission at 612 nm (5D0 → 7F2) indicates the most intense emission and the CIE chromaticity coordinates imply in the reddish-orange region.