Direct Optical Band Gap Energy Research Articles

Judd-Ofelt analysis and temperature sensing properties of polyethylmethacrylate (PEMA) networks doped with CdNb2O6: Er3+/Yb3+ phosphors

Research on the sensitivity of temperature measurements and optical thermometry involving rare earth ions has been an area of interest in the field of photonics and materials science. Introducing polymer networks as a new host material has an important role due to their properties including a versatile and stable environment for rare earth ions and rapid response in temperature detection. In this work, linear and crosslinked polyethylmethacrylate (PEMA) networks doped with Er3+/Yb3+ (1.5 mol % Er3+, 2 mol% Yb3+) synthesized by free-radical crosslinking polymerization with 0.1 EMA (weight %) at 60 °C were used to investigate direct and indirect optical bandgap energies and Urbach energy from UV–Visible spectra. The Judd-Ofelt (JO) approach was employed to analyze parameters Ωt (t = 2,4,6), spontaneous transition probabilities (Α), branching ratios (β) and radiative lifetimes (τ) as a function of linear and crosslinked PEMA doped nano-crystalline CdNb2O6: Er3+/Yb3+. The stimulated emission cross-sections of the transitions 2H11/2⟶4I15/2, 2S3/2⟶4I15/2 and 2F9/2⟶4I15/2 of Er3+/Yb3+ were calculated by two different methods; Fuchtbauer-Ladenburg formula and modified theory, respectively. The gain bandwidth cross-section product for the 2H11/2⟶4I15/2 was found to be 162.06. 10−28cm3, 260.94. 10−28cm3 and 461.20. 10−28cm3 of Er3+/Yb3+ embedded in linear, low and high crosslinked PEMA samples, respectively. JO parameters and stimulated emission cross-sections increased; therefore, radiative lifetimes decreased by increasing crosslinking content. In addition, the temperature dependence of upconversion (UC) luminescence was monitored under 975 nm excitation. The fluorescence intensity ratio (FIR) method examined the temperature sensing under two thermally coupled levels at 525 and 548 nm. The maximum sensitivities obtained from the FIR technique within the 300–650 K temperature range shifted to lower temperatures with increasing crosslinker content. Hence, linear and crosslinked polymer hosts doped rare-earth ions can be candidates for remote temperature sensors across various fields.

Optical and gamma-ray shielding properties of calcium sodium borate glasses with varied equal concentrations of ZnO and BaO

This study presents the optical and radiation shielding characteristics of a newly developed borate glass, doped with equal quantities of ZnO and BaO, and modified with calcium and sodium. The glass samples were prepared using the melt quenching technique, with the composition formula (80-x-y)B2O3-10CaO-10Na2O-xZnO-yBaO, where x and y were varied at 5, 10, 15, and 20 mol%. Comprehensive analyses of the optical and gamma shielding properties were carried out using UV–visible spectrophotometry and Phy-X software, respectively. The UV–visible spectroscopic data allowed for the calculation of various parameters including the direct and indirect optical energy band gaps, refractive index, dielectric constants, and polarizability. It was observed that the direct optical energy band gap decreased from 3.91 to 3.10 eV, while the indirect band gap fell from 3.41 to 2.91 eV with increasing ZnO and BaO content. Conversely, the refractive index rose from 2.29 to 2.42 with higher concentrations of ZnO and BaO. The linear attenuation coefficients (LACs) across the range of 0.015–15 MeV exhibited an inverse relationship. Among the glass samples, B40Zn20Ba20 exhibited the lowest tenth value layer (TVL) and the highest effective atomic number (Zeff), indicating its superior performance as a radiation shielding material. Overall, the produced glass samples demonstrate commendable properties for both optical applications and radiation shielding.

Optical, AC conductivity and antibacterial activity enhancement of chitosan-silver nanocomposites for optoelectronic and biomedical applications

This study is aimed to prepare and investigate the optical, electrical and antibacterial activity of the environmentally friendly (green) chitosan (Cs)/silver nanocomposites. TEM demonstrated that AgNPs have a spherical shape with particle size ranged from 3 nm to 25 nm. UV analysis spectra of Cs and Cs/Ag nanocomposites showed that, increasing the content of AgNPs led to a noticeable increase in the values of Urbach energy (E U ) and a dramatic decrease in both the indirect (E ig ) and direct (E dg ) optical bandgap energies. It is found that (E ig ) and (E dg ) are decreased from (4.72/5.31 eV) to (2.47/4.19 eV). The formation of the AgNPs is verified by the existence of surface plasmon resonance (SPR) peak at ∼ (421–450) nm. Wemple-DiDomenico and Sellmeier oscillator models are employed and displayed a clear enrichment in the dispersion energy (E d ) and oscillator energy (E 0) as well as the linear and nonlinear optical parameters of Cs. It is observed that the linear (χ(1)) and nonlinear (χ(3) and n2) parameters are enhanced from 0.083, 0.868 × 10−14 and 1.584 × 10−12 to 0.153, 9.762 × 10−14 and 4.088 × 10−12. The novel results in our study nominate Cs/Ag nanocomposites for applications in linear/nonlinear optical devices. AC conductivity behavior of Cs and Cs/Ag nanocomposites is analyzed based on Jonscher’s law and the analysis showed that the overlapping large polaron tunneling (OLPT) is the dominant conduction mechanism for our samples. It is clear that the values of dielectric constant (ε′) of Cs and Cs/Ag nanocomposites are higher confirming the presence of interface polarization (IP) relaxation. Moreover, it is found that the antibacterial activity of Cs against Gram-negative (P. aeruginosa) and Gram-positive (B. thuringiensis) bacteria is found to be enhanced with increasing the content of Ag NPs. These results suggested that Cs/Ag nanocomposites will be good source for preparing bio-nanocomposites for use in many biomedical and industrial applications.

Insight into deposition duration-varied crystallinity, optical parameters, morphology and electrical properties of solution-processed nanostructured CdSSe thin films

Nanostructured cadmium sulpho selenide (CdSSe) films have been grown onto glass substrates for different deposition durations via a facile solution-based method known as chemical bath deposition (CBD). XRD studies revealed that the crystallites in the films possessed hexagonal (wurtzite) structures with predominant orientation along the (002) plane. The crystallite size increased from ∼5.95 nm to ∼16.69 nm with the increase in deposition duration from 1 h to 4 h. The absorbance, transmittance and reflectance measurements were carried out. A transparency of ∼(50–80) % was obtained for the films. The direct optical energy band gap was found to decrease from 1.982 eV to 1.952 eV with the increment of deposition duration from 1 h to 4 h. SEM micrographs of the films revealed the presence of nano spherical-shaped grains with an average size ranging from ∼305 nm to ∼612 nm. HRTEM images illustrated the presence of compact nano-spherical grains and nano-crystallites distributed in random orientations. Raman spectroscopy divulged the presence of CdSe and CdS vibrational Raman modes and overtones in the films. PL spectra revealed a prominent red emission band along with weak luminescent bands in the yellow-red emission region. The presence of Cd–Se and Cd–S bonds in the films was validated using FTIR analysis. Electrical investigation revealed the linear current‒voltage relationship for the films with the rise in conductivity with deposition duration. Hence, deposition duration stands out as a vital parameter for modulating the properties of CdSSe thin films for use in photovoltaic devices and optoelectronics.

Green synthesis of zinc oxide nanoparticles using Terminalia arjuna bark extract: structural, optical and photocatalytic study

Abstract Zinc oxide (ZnO) nanoparticles have been successfully synthesized by using Terminalia arjuna bark extract via a green route. Structural analysis using X-ray diffraction confirmed the prepared samples are crystalline having hexagonal wurtzite structure with space group P63 mc and average crystallite size is found to be 8.93 nm. Rietveld refinement of the data was carried out using Material Analysis Using Diffraction (MAUD) software and reliability parameters of the refinement have been obtained. Optical properties of the sample investigated by ultraviolet – visible diffuse reflectance spectroscopy reveal an absorption peak to lie at 348 nm and the direct optical band gap energy using Kubelka–Munk function is found to be 3.20 eV. Morphological investigation using scanning electron microscopy revealed that ZnO nanoparticles are nearly spherical and agglomerated. Energy-dispersive X-ray spectrometry analysis showed the presence of Zn and O only. Transmission electron microscopy imaging confirmed the predominant hexagonal structure of the prepared nanoparticles having average particles size of 9.66 nm, which is in agreement with the X-ray diffraction result. Fourier transform infrared spectroscopy was used to identify the functional groups and different vibrational modes present in the sample. The photocatalytic activity of the prepared ZnO nanoparticles was studied using methylene blue (MB) dye under a single wavelength UV light source (λ = 254 nm). The degree of degradation of MB solution was about 56 % within 120 min of illumination to UV light and the degradation reaction follows first order kinetics with rate constant 0.00434 min−1.

Effect of polypyrrole incorporation amounts on the optical and electrical properties of PVA/CMC blended polymer for optoelectronic applications

In the present work, hybrid flexible blended polymers of polypyrrole (PPy)/polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC); PVA/CMC/x wt % PPy; were constructed as promising blended materials to be used in various optoelectronics applications. X-ray diffraction and scanning electron microscopy techniques were used to investigate the structure and the surface morphology of polymer nanocomposites. The doped blends have better absorption of the three types of ultraviolet (UVA, UVB, and UVC), as well as the visible spectrum. The transmittance values in the visible range dropped from 90 % to 63 % as the PPy concentration reached 0.5 wt%. At x = 0.5, the minimum direct and indirect optical band gap energy values of (4.82, 4.39, 4.23) eV and (3.76, 3.84, 3.62, 2.93) eV, respectively, were obtained. The incorporation of PPy into the PVA/CMC blend led to a regular rise in the refractive index value within the visible range. The blend doped with 0.5 wt % PPy exhibited the highest optical dielectric constant values within the visible range. The enhancement/reduction in the fluorescence intensity depended on the excitation wavelength and the amount of PPy doping in the blended polymers. The effect of voltage, temperature and the amount of PPy doping on the current behavior of the resulting electric current in all blends was explored. The ohmic and nonohmic natures and the charge transport mechanisms of different blends were determined.

Structural, optical and electrical conduction characteristics of PMMA/PVAc/TBAI blended polymers

This study aims to create tetra-n-butylammonium iodide (TBAI) doped poly(methyl methacrylate) (PMMA)/polyvinyl acetate (PVAc) blended polymers for utilize in a diversity of optoelectronic applications. By the casting technique, the films of (PMMA/PVAc/x wt % TBAI) were formed. The structure and morphology characteristics of the blended materials were studied using X-ray diffraction and scanning electron microscopy techniques. The optical transmittance declined to a minimum value when the blend was loaded with 38 wt % TBAI. The blend containing 38 % TBAI exhibits the highest reflectance values in the visible range. The lowest direct optical bandgap energies (4.20 eV) and indirect optical bandgap energies (3.71 eV, 3.13 eV) were achieved when TBAI reached 38 wt%. The addition of TBAI leads to an enhancement of the refractive index values of PMMA/PVAc in the visible spectrum. The effect of TBAI doping amount on the optical dielectric constant, energy loss functions, optical conductivity, nonlinear optical parameters and emitted color of the host blend was explored. The maximum values of the optical dielectric constant and energy loss functions were achieved after the TBAI level reached 38 wt%. The three non-linear optical (NLO) parameters for PMMA/PVAc blended polymers were enhanced as the amount of TBAI increased. An increase in voltage (V) or temperature results in a significant increase in electric current (I). Raising the amount of TBAI doping also caused the electric current to rise irregularly, with the exception of the blend with x = 11 %, where it fell. The samples exhibited the non-ohmic characteristics of the current-voltage (I–V) properties. The conduction mechanism of all blended materials was studied in detail. Finally, the outcomes supported the optical and electric properties studies, which suggested that a range of nanoelectronics applications could make use of the PMMA/PVAc/x weight percent TBAI blended polymers.

Elaboration, Structural and Optical Characterization of the New Ternary Chalcogenide SnSb<sub>2</sub>S<sub>5</sub>

In this study, -antimony sulfide (SnSb2S5) thin films with 200 nm, 312 nm, and 431 nm thicknesses were successfully fabricated using thermal evaporation. These films' structural, optical, and photoanode properties were meticulously characterized to assess their suitability for photovoltaic applications. X-ray diffraction (XRD) analysis confirmed the presence of an orthorhombic symmetry phase within the <em>Pnma</em> space group, ensuring the crystalline quality of the films. Raman spectroscopy further validated the crystal structure and provided detailed identification of the vibrational active modes specific to this pseudo-binary chalcogenide compound. Optical characterization revealed that the SnSb<sub>2</sub>S<sub>5</sub> thin films possess direct optical bandgap energies ranging from 1.91 to 1.99 eV, making them ideal for efficient light absorption in photovoltaic devices. The refractive index (n) displayed minimal variation within the absorption region, indicating stable optical properties. At the same time, it increased proportionally with film thickness outside the absorption region, suggesting enhanced optical behavior with thicker films. This characteristic is particularly advantageous for improving the efficiency of photoanode materials. The combination of favorable structural properties, optimal bandgap energies, and tunable optical responses positions SnSb<sub>2</sub>S<sub>5</sub> thin films as promising candidates for advanced photovoltaic and optoelectronic applications. These findings highlight the potential of SnSb<sub>2</sub>S<sub>5</sub> in developing high-performance photoanodes, contributing to the advancement of solar energy conversion technologies.

PVA/PEG/CuCo2O4/PANi/x wt% MWCNTs blended polymers: Improved the physical properties for energy storage devices and optoelectronic applications

The current investigation aims to enhance the optical and dielectric properties of poly (vinyl alcohol) (PVA)/polyethylene glycol (PEG) blended polymers via loading with copper cobaltite (CuCo2O4), polyaniline (PANi), and x wt% multi-walled carbon nanotubes (MWCNTs) for potential applications in optoelectronics and capacitive storage. The fabrication of PVA/PEG/CuCo2O4/PANi/x wt% MWCNTs blended polymers was carried out via casting and hydrothermal methods. Characterization of the blended polymer's structure and morphology was conducted using X-ray diffraction and scanning electron microscopy techniques. The impact of various fillers on the linear and nonlinear optical properties of the host blend was analyzed. The loaded blends demonstrated efficacy in blocking UVA, UVB, and UVC spectra, making them suitable absorbers for solar cells. The lowest values for direct and indirect optical band gap energy (Eg), of 5.34 eV and 4.44 eV were attained at x = 0.02. The blend with x = 0.01 displays the highest refractive index at λ = 600 nm. The optical conductivity exhibited nonmonotonically growth until peaking at x = 0.01. Analysis of chromaticity diagrams in CIE 1931 color space reveals that all blends emit blue-violet hues with slight variations in intensity. The fluorescence (FL) intensity of the doped blend is notably lower compared to the undoped counterparts. The doped blend (x = 0.03) showcases superior dielectric constants and ac conductivity values. The maximum energy density was achieved at 1 kHz for the host blend incorporating CuCo2O4/PANi. Overall, the observed characteristics indicate that PVA/PEG/CuCo2O4/PANi/x wt% MWCNTs blended polymers represent promising hybrid nanomaterials suitable for diverse applications.

Diisopropylammonium hydrogen squarate: Synthesis and comprehensive analysis of non-linear optical co-crystal using X-ray, Hirshfeld, mechanical, optical and DFT methods

This research successfully synthesized a single co-crystal of diisopropylammonium hydrogen squarate using prolonged vaporization for crystal growth. Single-crystal X-ray spectrometry confirmed its monoclinic structure, and morphological predictions were made. UV–visible spectroscopy revealed its optical transmittance with a direct optical energy band gap of 3.45 eV. Photoluminescence studies showed a strong violet emission at 402 nm when excited by a 260 nm source. Microhardness study examined the crystal's mechanical attributes portraying the normal indentation size effect followed by a qualitative overview of half-penny crack dynamics. FTIR study aided in the discernment of varied vibrational modes with NH stretching being observed at 3078 cm−1. Thermal examination further revealed the crystal's stability up till 244 °C. Proton and carbon-13 NMR spectra were analyzed to verify the presence of functional groups and the overall molecular integrity. Intermolecular interactions were analyzed using Hirshfeld surface and fingerprint mapping. The Z-scan technique demonstrated the crystal's applicative potential in its third harmonic generation capability. Theoretical calculations with Density Functional Theory (DFT) supported the experimental findings, offering insights into optimized geometries, frontier molecular orbitals, natural population and bond orbital distributions, hyperpolarizability, molecular electrostatic potentials, IR vibrational modes, and UV absorbance profiles.

An Insight into the Impact of Nano CuCo2O4 Doping on the Optical and Dielectric Performance of PMMA/Carbon Nanoparticles

In the present study, novel functional properties were achieved for polymethyl methacrylate (PMMA) through loading with carbon nanoparticles (CNPs) as well as varying quantities of CuCo2O4 nanoparticles. The blends obtained were subjected to different characterization techniques. Extensive investigations of different optical properties were carried out, covering linear and nonlinear optical properties. After the incorporation of CNPs/CuCo2O4 in the host polymer matrix, the absorbance, reflectance and refractive index exhibited improvements, while continuous reductions in both direct and indirect optical band gap energies were observed. Significant improvements in the linear and nonlinear optical parameters were observed with increasing CuCo2O4 doping levels. Dielectric measurements provided insights into the impact of CuCo2O4 content on the ac conductivity, energy density, dielectric properties, and electric modulus across all blends. The sample doped with 1.5 wt% exhibited the highest dielectric constant. In conclusion, the optical and dielectric properties of the PMMA/CNPs/x wt% CuCo2O4 blends make them promising candidates in optoelectronics and photocatalysis applications.

Fabrication and adapting the optical, and dielectric performance of PVC/ MnFe2O4/ZnMn2O4 nanocomposite films for optoelectronic applications

The current study focuses on the fabrication of hybrid flexible polymers composed of MnFe2O4/ZnMn2O4 nanocomposites doped polyvinyl chloride (PVC). The doped polymers show great potential for utilization in a wide range of optoelectronics applications. PVC/(1-x)MnFe2O4/xZnMn2O4 were made using the casting and sol gel processes. The effect of (1-x)MnFe2O4/xZnMn2O4 nanocomposite samples on the optical parameters of PVC polymer has been explored using ultraviolet–visible diffused reflectance measurements. Doped polymers might be useful as protective barriers against ultraviolet radiation of various wavelengths (UVA, UVB, UVC) and as excellent absorber materials for solar cells. The direct and indirect bandgaps (Eg) of PVC are 4.26 and 4.08 eV. The direct/indirect optical band gap lowered to their lowest 3.97/3.45 eV as the PVC doped with nanofillers contained 50 %/80 % ZnMn2O4, respectively. Different models were used to extracted the refractive index (n) of different polymers based on the obtained optical band gaps (direct/indirect). Doped polymers containing 50 and 80 % ZnMn2O4 had the highest n values using direct and indirect Eg values, respectively. The n value (obtained from the direct optical bandgap energy) of PVC increased from 2.209 to the maximum value (2.262) as x = 0.5. The n value (obtained from the indirect optical bandgap energy) of PVC increased from 2.349 to the maximum value (2.367) as x = 0.8. All linear and nonlinear optical parameters of PVC polymer were improved as it doped with the nanocomposite fillers. The fluorescence (FL) intensity of PVC was reduced as it was doped with (1-x)MnFe2O4/xZnMn2O4 and this intensity reduced as the content of ZnMn2O4. The standard (CIE) color space chromaticity diagram was used to analysis the FL spectra for different samples. The effect of nanocomposite samples on the AC conductivity, dielectric constants and electric modulus of the PVC was studied. At 1 kHz, the dielectric constant of PVC was increased from 11.745 to 12.906 and 12.096 for polymers with x = 0 and x = 0.2, respectively. The enhanced optical and dielectric properties of the PVC/(1-x)MnFe2O4/xZnMn2O4 polymers nanocomposites suggest that these materials are suitable for smart electronic devices.

Melt-quenched zinc sodium borate glasses: Understanding the role of ZnO/Na2O ratio in density, band gap, and radiation attenuation

In this work, we successfully prepared glasses with the composition 55 B2O3 – (45-x) ZnO – x Na2O (x = 0, 5, 10, 15) using the traditional melt quenching procedure. We analyzed the influence of substituting ZnO with Na2O at different concentrations on the attenuation of ionizing radiation and the glass density. Different analytical tools, such as XRD, FTIR, and UV-VIS spectroscopy, were used to investigate the crystal structure and optical features of the produced samples. The partial replacement of ZnO by Na2O significantly reduces the density (from 3.36 to 2.87 g/cm3) and, in contrast, increases the molar volume of the glass (from 22.32 to 25.06 cm3/mol). The positions of the main peaks in the FTIR spectra remain relatively unchanged with increasing Na₂O content. The Fermi energy (EF) of the glasses increases from 3.16 to 3.45 eV with increasing Na2O concentration. Samples with higher Na2O exhibit a blue shift in the UV cutoff. The direct and indirect optical band gap energy values (Ed/Ein) increase from 3.42 to 3.62 eV and 2.87–3.23 eV, respectively, with increasing Na2O concentration. The radiation attenuation performance of these glass samples was examined through evaluation of various parameters like linear and mass attenuation coefficients (LAC/MAC), effective atomic number (Zeff), and half-value layer (HVL) and tenth-value layer (TVL) in the photon energy range of 10 keV–15 MeV. LAC and MAC values decrease with decreasing ZnO content. The two buildup factors, energy (EBF), and energy absorption (EABF) have been recorded for the different compositions at penetration depths up to 40 mean free paths. Samples with the highest ZnO concentration show the lowest HVL and TVL values at the lowest photon energy (≤2 MeV). Increasing Na2O concentration significantly increases both EBF and EABF, with their maxima occurring at 5 MeV. Increasing zinc oxide in the glass improves its radiation shielding ability, suggesting potential applications for zinc alkali borate glasses in radiation protection.

Structural, Physical and Optical studies of Sc3+ doped Lithium Aluminum Borate glasses

Optically transparent lithium aluminum borate containing scandium glasses with composition 70B2O3 – 20Li2O – (10 – x) Al2O3 – xSc2O3 (where x= 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 in mol %) were fabricated by conventional melt quenching technique. The non-crystalline nature of the samples was monitored by X-ray diffraction and it confirms non-crystalline nature. Structure of the fabricated glasses are assessed using the Fourier transform infrared spectra. The absorption spectra of these glasses have been recorded in the wavelength range 200 nm – 1100 nm. Direct and indirect optical energy band gaps were calculated from Tauc’s plots. The physical parameters such as refractive index (RI), optical basicity and interaction parameters were determined using proper formulas to know the characteristics of fabricated glass matrix. The results obtained indicate that 0.3 mol% Sc2O3-containing BLASc glass is more suitable for w-LEDs and lasers applications.

Optical and Dielectric Characteristics of Poly (Methyl Methacrylate)/Polyethylene Oxide/Carbon Nanoparticle Composites Loaded with Nano NiFe2O4

The current study proposes a simple, low-cost, and functional method of doping a pure matrix of poly (methyl methacrylate)/polyethylene oxide/carbon nanoparticles (PMMA/PEO/CNPs) with nano nickel ferrite (NiFe2O4) as a filler. To create NiFe2O4 nanoparticles, a straightforward chemical growth, sol-gel auto-combustion system was used. Next, environmentally friendly and cost-effective, undoped and blended polymers doped with NiFe2O4 using a solution-casting method were synthesized. Rietveld refinement analysis was used to investigate the structure and microstructure of the NiFe2O4. Transmittance electron microscopy was used to confirm the nano nature of the filler. X-ray diffraction was used to verify the crystallite nature of the undoped and doped PMMA/PEO/CNPs blends with NiFe2O4. The linear optical characteristics of the proposed blends were obtained using a diffuse reflectance spectrophotometer. The measured optical parameters included transmittance, absorbance, reflectance, direct and indirect optical bandgaps, absorption coefficient, linear refractive index, extinction coefficient, dielectric constant, energy loss functions, in addition to optical and electrical conductivities. Also, nonlinear optical constants for the synthesized blends, such as the linear and third nonlinear susceptibilities, nonlinear refraction coefficient and nonlinear absorption coefficient, were calculated. The direct and indirect optical band gap energies of the PMMA/PEO/CNPs blends were 4.97 and 4.8 eV, respectively. As the NiFe2O4 doping level increased in the blend to 2.5 wt%, the optical band gap energy values decreased to 4.54 and 4.64 eV, respectively. The fluorescence spectra of the undoped and doped PMMA/PEO/CNPs blended polymers with nano NiFe2O4 were also explored. The effect of NiFe2O4 doping amount on the energy density, electric dielectric constant, ac conductivity and electric moduli of the host blend was also studied. In conclusion, the considered NiFe2O4-doped PMMA/PEO/CNPs blends have an effective and promising role in optoelectronic applications.

Optical properties and luminescence behavior of Tb3+-Doped SiO2–Al2O3–BaO–BaF2 oxyfluoride glasses and glass ceramics

In this study, oxyfluoride glasses with chemical composition of 45SiO2–15Al2O3–10BaO–30BaF2-xTbF3 (x = 0.2, 0.4 and 0.6 (mole ratios)) were prepared through the conventional melt-quenching method. Raman and FTIR spectra as well as molar volume calculations proved the creation of more non-bridging oxygens (NBOs) in presence of more TbF3 content. Accordingly, absorption edge in UV–Vis spectra showed a slight red-shift to longer wavelengths. The glass with 0.4 mol ratios of TbF3, exhibited the highest photoluminescence emission and its green-to-blue intensity ratio was 0.66. Therefore, this sample was chosen and heat treated at 630, 650 and 675 °C to prepare glass ceramic samples. For the sample heat treated at 650 °C, photoluminescence intensity increased and green-to-blue intensity ratio reached 0.69. Also, lifetimes of green and blue emissions increased from 3.35 ms to 3.67 ms and from 2.95 ms to 3.10 ms, respectively, when the base glass heat treated at 650 °C. Formation of BaF2 nanocrystals in glass ceramics moved the UV–Vis absorption edge to longer wavelengths significantly. Increment of the weak and dangling bonds in crystallized samples reduced Fermi energy, indirect and direct optical band gap energies from 3.792 eV to 3.301 eV, from 3.522 eV to 3.093 eV and from 4.095 eV to 3.582 eV respectively, which led to higher semiconducting behaviors.

Influence of Al Doping on the Structural, Optical, and Electrical Characteristics of ZnMn2O4

Doped zinc manganite samples were synthesized using the sol-gel method, incorporating varying amounts of aluminum (ZnMn2-xAlxO4, x = 0, 0.03, 0.05, 0.07, 0.1). High quality X-ray diffraction data enabled detection and accurate quantification of the predominant phase ZnMn2O4 (ZMO) and minor phase ZnO. The structure and microstructure of developed phases were investigated applying the Rietveld refinement method. The nanoscale nature of the samples was examined by High-resolution transmission electron microscopy (HRTEM); the incorporation of Al into the ZMO matrix and the oxidation states of various cations were studied through X-ray photoelectron spectroscopy (XPS). The introduction of Al has resulted in a modification of the light-absorption characteristics of the ZMO sample. Specifically, the direct optical band gap energy of ZMO decreased from 2.45 to 2.25 eV with an increase in the amount of Al doping to 0.1. Moreover, an investigation was conducted into the impact of Al doping amount, frequency, and temperature on the dielectric constant, dielectric tangent loss, ac conductivity, complex impedance, and complex electric modulus. It was observed that all samples, except for the sample with x = 0.05, exhibited ferroelectric features. The activation energies for the samples with x = 0, 0.03, 0.05, 0.07, and 0.1 were determined to be 0.274, 0.456, 0.099, 0.103, and 0.152 eV, respectively. The conduction mechanism type in the different samples was identified. The obtained changes of dielectric properties indicated the capability of improving the ZMO characteristics for various applications via controlling the doping content of Al.

Response of the modified GAFCHROMIC EBT2 radiochromic film to DC glow discharge plasma

The response of the modified GAFCHROMIC EBT2 radiochromic film to DC Oxygen glow discharge plasma was investigated using a flatbed scanner and an UV–Vis spectrophotometer. The film was modified by removing the polyester overlaminate, adhesive, and topcoat layers with a total thickness of 80 µm, and is now referred to as EBT2-M. The EBT2-M films were exposed to DC Oxygen plasma for different durations: 0, 0.5, 1, 2, 3, 4, 7, and 10 min. The exposed films exhibit coloration homogeneity with an average variation of (1.6 ± 0.3) × 10−4 pixel values/µm, irrespective of the applied exposure time. The pixel values of the red-and-green channels and weighted grayscale images decreased exponentially with different sensitivity amounts to ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 39.67, 49.69, and 42.11 min−1, respectively, as the exposure time increased. The two absorption peaks at 580 ± 4 nm and 632 ± 4 nm in the UV–Vis absorption spectra of the exposed GAFCHROMIC EBT2-M radiochromic films are increasing with increasing exposure time up to 4 min, thereafter saturated for prolonged exposure time. The integrated absorbance in the range from 400 to 700 nm is linearly correlated with the exposure time. The indirect and direct optical energy band gaps and Urbach energy of the modified GAFCHROMIC EBT2 film are weakly correlated with the exposure time. These findings suggest the utilization of the modified GAFCHROMIC EBT2 radiochromic film as a novel and simple technique for plasma diagnostics.

Optical, Dielectric, and Electromagnetic Microwave Absorption Properties of Hexagonal Ba3(VO4)2

In this work, we used a simple sol-gel synthesis technique to prepare hexagonal Ba3(VO4)2. X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopy were performed, confirming that Ba3(VO4)2 has a hexagonal structure. To investigate the influence of interfacial interactions at grain boundaries on microwave absorption, AFM studies were performed. UV–vis studies show the direct and indirect optical energy band gaps of Ba3(VO4)2 were determined as 3.81 eV and 3.25 eV, respectively. The dielectric studies reveal that the dielectric constant (ε׳) of Ba3(VO4)2 ranges from 1.55 to 6.02 in the frequency range of 2–20 GHz, with an average ε׳ value of 3.84. The microwave absorption properties of Ba3(VO4)2 were evaluated in the frequency range of 8–18 GHz, covering the X and Ku bands at different thicknesses from 4.5 mm to 8 mm. The highest effective absorption bandwidth (EAB) of 4.44 GHz was observed within the frequency range of 12.83–17.27 GHz, with a maximum reflection loss of −71.43 dB at a resonance frequency of 15.05 GHz. Additionally, at a thickness of 7.5 mm, Ba3(VO4)2 achieved a maximum reflection loss of −75.22 dB at 10.03 GHz, with an EAB of 2.94 GHz (covering the X band from 8.57 GHz to 11.51 GHz).

LDPE/Bi2O3 nanocomposites: Enhanced mechanical, dielectric, and optical properties

AbstractThis study is focused on investigating the role of bismuth oxide (Bi2O3) nanoparticles to improve structural, optical, electrical, and mechanical properties of low‐density polyethylene (LDPE). For this purpose, Bi2O3 nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x‐ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE‐based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n‐Bi2O3 composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n‐Bi2O3 composite. In this context, the LDPE/0.5% n‐Bi2O3 composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE‐based nanocomposite with better properties for industrial purposes.