Optical Band Gap Values Research Articles

Effect of Ca, Ba, Be, Mg, and Sr Substitution on Electronic and Optical Properties of XNb2Bi2O9 for Energy Conversion Application Using Generalized Gradient Approximation–Perdew–Burke–Ernzerhof

Bismuth layered structure ferroelectrics (BLSFs), also known as Aurivillius phase materials, are ideal for energy-efficient applications, particularly for solar cells. This work reports the first comprehensive detailed theoretical study on the fascinating structural, electronic, and optical properties of XNb2Bi2O9 (X = Ca, Ba, Be, Mg, Sr). The Perdew–Burke–Ernzerhof approach and generalized gradient approximation (GGA) are implemented to thoroughly investigate the structural, bandgap, optical, and electronic properties of the compounds. The optical conductivity, band topologies, dielectric function, bandgap values, absorption coefficient, reflectivity, extinction coefficient, refractive index, and partial and total densities of states are thoroughly investigated from a photovoltaics standpoint. The material exhibits distinct behaviors, including significant optical anisotropy and an elevated absorption coefficient > 105 cm−1 in the region of visible; ultraviolet energy is observed, the elevated transparency lies in the visible and infrared regions for the imaginary portion of the dielectric function, and peaks in the optical spectra caused by inter-band transitions are detected. According to the data reported, it becomes obvious that XNb2Bi2O9 (X = Ca, Ba, Be, Mg, and Sr) is a suitable candidate for implementation in solar energy conversion applications.

Fabrication of a highly efficient CuO/ZnCo2O4/CNTs ternary composite for photocatalytic degradation of hazardous pollutants.

In the current study, CuO, ZnCo2O4, CuO/ZnCo2O4, and CuO/ZnCo2O4/CNTs photocatalysts were prepared to remove crystal violet (CV) and colorless pollutants (diclofenac sodium and phenol) from wastewater. Herein, sol-gel and co-precipitation methods were used to synthesize CuO and ZnCo2O4, respectively. The sonication method was used to synthesize CuO/ZnCo2O4 and a CNTs-based composite (CuO/ZnCo2O4/CNTs). From the UV-Vis spectra of CuO, ZnCo2O4, CuO/ZnCo2O4, and CuO/ZnCo2O4/CNTs, the optical band gap value was calculated to be 2.11, 2.18, 1.71 and 1.63 eV respectively. The photocatalytic results revealed that CuO/ZnCo2O4/CNTs exhibited higher degradation of 87.7% against CV dye, 82% against diclofenac sodium, and 72% against phenol as compared to other prepared photocatalysts. The OH˙ radical is identified as the active species in the photocatalytic process over CuO/ZnCo2O4/CNTs. The impact of several parameters, such as pH, concentration, and catalyst dosage, has also been investigated. The better activity of the CNTs-based composite was due to the synergic effect of both CuO/ZnCo2O4 nanocomposite and carbon nanotubes. Therefore, the synthesized CuO/ZnCo2O4/CNTs photocatalyst has the potential to degrade organic wastewater effluents effectively.

TL, EPR, and optical properties of undoped and Eu-, Ce-, Tb-, Sm-, Cu-, Mn-, and Li- doped MgSiO3 phosphors, synthesized by sol-gel combustion technique

Polycrystalline MgSiO3 samples, undoped or doped with rare earth- (Eu, Tb, Ce, Li, Sm), transition- (Mn and Cu), and alkali metal- (Li) elements, were prepared by the sol-gel combustion method and characterized by thermoluminescence, electron spin resonance, and optical properties. Enstatite and protoenstatite phases are observed in undoped and doped MgSiO3. Better TL results have been observed for phosphors doped with Tb, Ce, and Li (0.5 % mol). Fading experiments and the GCD method have been performed. EPR signals of gamma-irradiated phosphors indicate the formation of radiation-induced defect centers. Cu-doped MgSiO3 shows an unusual feature of the Cu2+ ion. The Cu2+ ion occupies a tetragonally compressed octahedral site, presenting an unconventional attribute. Optical bandgap value Eg is higher for the Ce, Tb, Mn, Li, Sm, and Cu-doped MgSiO3 phosphors. Ce, Li, and Tb dopant ions were found suitable for the MgSiO3 sample regarding its thermoluminescent response and its possible application in radiation dosimetry.

Preparation and characterization of PVA/MWCNT nanocomposites: a composition dependence study of structural, optical and mechanical properties

This work investigates the properties of polyvinyl alcohol (PVA) nanocomposite films with varying multi-walled carbon nanotube (MWCNT) content, ranging from 2 to 8 wt.%. The films were prepared using a solution casting method and characterized using UV-visible spectroscopy, optical microscopy, X-ray diffraction, and tensile tests. The prepared PVA/MWCNT nanocomposite films exhibited optical band gap values ranging from 3.5 eV to 5.3 eV. XRD analysis confirmed the semi-crystalline nature of these nanocomposites. Mechanical properties, including hardness, yield strength, ultimate tensile strength, and Young’s modulus, were enhanced by increasing MWCNT content by up to 8%. Contact angle measurements showed an increase in hydrophobicity with increasing MWCNT content. Optical microscopy images revealed uniform dispersion of MWCNTs in the PVA matrix. These findings suggest potential applications of PVA-MWCNT nanocomposites in various fields, including photosensors, UV shielding, adjustable band gap devices, and flexible optoelectronic devices.

Interface state density in mist chemical vapor deposited Al2O3/AlGaN/GaN structure

Uniform thickness Al2O3 thin films have been deposited by eco-friendly mist CVD. The obtained Al2O3 film has an optical band gap value of more than 6.5 eV and a refractive index of 1.64 at 633 nm. The combination of capacitance–voltage (C–V) fitting method with non-linear least-squares algorithm, frequency dispersion, photo-assisted, and proposed reverse bias-assisted C–V methods revealed interface state densities ranging from 1 × 1012 to 3 × 1013 cm−2eV−1 along the mist-Al2O3/AlGaN interface. These values are comparable to those reported for atomic layer deposited Al2O3 thin films.

Investigating the structural and magnetic properties of Fe3Se4 nanoparticles and it's photocatalytic application

This study explores the potential of synthesized Fe3Se4 nanoparticles by solid-state reaction method and it's photocatalytic application. The structural parameters validated by X-ray diffraction (XRD) demonstrate a monoclinic structure. The particle size of the prepared material was estimated at approximately 95 nm, as observed by field emission scanning electron microscopy (FE-SEM) and it's composition was verified by energy dispersive spectroscopy (EDS). Strong Raman modes were observed at 225 cm−1 which is responsible for lattice vibration in Fe3Se4. Both Fe2+ and Fe3+ oxidation states were present in Fe3Se4, as characterized by X-ray photoelectron spectroscopy (XPS). From the thermal gravimetric analysis (TGA) curves, the Fe3Se4 was confirmed to be stable up to 295 °C. vibrating sample magnetometer (VSM) tests revealed that the coercivity was 151 Oe at ambient temperature and increased 20 times to 2425 Oe at 15 K. Tauc's plot indicated an optical band gap value of 1.12 eV. Fe3Se4 nanoparticles achieved an 80.79 % dye degradation efficiency and exhibited photocatalytic activity against methylene blue dye. In photocatalysis, the apparent pseudo-first-order k1 and pseudo-second-order k2 rate constants are 0.018 min−1 and 0.058 min−1.

Exploring the optical and electrical features of PVA/CMC/PPy/MWCNTs blended polymers

The objective of this study is to create nanocomposite films using polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), polypyrrole (PPy) and Multi-walled carbon nanotubes (MWCNTs). These nanocomposites show potential for use in a range of optoelectronics devices. The structure and morphology of PVA/CMC/PPy/x wt % MWCNTs blends were explored using X-ray diffraction and scanning electron microscope techniques. In the visible range, the transmittance lowered from 78 to 87 % (PVA/CMC/PPy blend) to 3–5 % (x = 0.25 wt % MWCNTs). The transmittance in the UV range decreased significantly, approaching zero, for the blend containing 0.25 wt % MWCNTs. The material improves the absorption of UV–visible light and efficiently prevents the penetration of UV–visible light. When the concentration of MWCNTs reached 0.05 in the doped blend, the reflectance value improved considerably. The addition of MWCNTs to the PVA/CMC/PPy composite leads to a reduction in the optical bandgap values. The lowest direct and indirect band gaps are (4.98, 4.36) eV and (4.52, 3.19, 2.68, 1.18) eV, respectively, accomplished when the MWCNTs content was 0.2 wt %. A blend containing 0.15 wt % MWCNTs resulted in the highest values of refractive index and nonlinear optical parameters. In the visible light spectrum, the blend with 0.25 wt% MWCNTs had the best optical conductivity values. Doped blends can be used in optoelectronic or photocatalytic applications depended on the amount of MWCNTs doped. The current-voltage characteristics and logarithm of the current density and square root of the electric field strength of PVA/CMC/PPy/x wt % MWCNTs blended polymers at various temperatures were investigated.

Nebulized spray pyrolysis deposited CdO thin films for liquefied petroleum gas and ethanol gas sensor

High quality cadmium oxide (CdO) thin films were prepared through an inexpensive and simple nebulized Spray Pyrolysis (neb-SP) technique. The transparent conducting CdO thin films deposited at different substrate temperatures (TS) for the ethanol and liquefied petroleum gas (LPG) sensor application. XRD, SEM, UV–vis Spectroscopy and Hall Effect were done to study the structural, morphological, optical and electrical properties respectively. Polycrystalline nature thin films shows (1 1 1) cubic structure as the prominent peak. Surface morphology studies reveal that the grain size and roughness of the films are increased with increase in the substrate temperature. The average transmittance of the yellowish transparent CdO thin films is about 57%, thus the films are transparent in the visible region. The optical band gap (Eg) value of the CdO films increased from 2.16 to 2.28 eV with increase in the TS from 225 °C to 300 °C. The minimum value of electrical resistivity of the films is 1.40 × 10−3 Ωcm obtained at 275 °C. The neb-SP deposited CdO thin film (275 °C) shows maximum response to the ethanol and LPG gas sensitivity of 31.87% and 16.4% respectively at operating temperature of 573 K. Thus the results authenticate that the CdO thin films deposited low substrate temperature with high quality can be achieved via neb-SP technique compared to other wet chemical or physical method.

Investigation of structural, elastic, thermal, magnetic, optical, and photocatalytic properties of nanosized Mg-Mn-Li ferrites

Nanoferrites of (Mn1-xMgx)0.8Li0.1Fe2.1O4 (x: 0–1.0, step 0.2) were synthesized by the sol–gel autocombustion method. The structural properties of the samples were characterized by X-ray diffraction, particle size analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The X-ray diffraction patterns for the samples establish the nanoscale (38–54 nm) pure-phase spinel cubic structure (Fd-3̅\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{3}$$\\end{document}m). Also, the particle size analysis results demonstrate the narrow distribution of their particle sizes, which range from 10 to 33 nm. The impact of Mg2+ ion concentration on the thermal, elastic, magnetic, and optical properties of these samples was studied. The saturation magnetization decreases from 56.9 to 31.1 emu/g, and the coercivity increases from 65.8 to 106.8G with the addition of Mg2+ ions, showing thin S-shaped hysteresis loops revealing the samples’ soft magnetic behavior. Thermal results indicate that these samples are interesting candidates for thermoelectric applications due to their noticeably lower thermal conductivity, which ranges from 0.3572 to 0.5881 W/mK. The optical band gap values determined by using ultraviolet-visible diffuse reflectance spectroscopy range from 5.11 to 5.25 eV, where quantum confinement for crystallite size triggers a larger band gap. As the concentration of Mg2+ ions increases, their ability to degrade methyl green dye under ultraviolet radiation for 100 min rises from 13.6 to 61.1% with the addition of H2O2, an indication of their photocatalytic activity. Moreover, the optimum ferrite sample, Mn0.4Mg0.4Li0.1Fe2.1O4, maintained its photocatalytic efficiency for at least six reaction cycles.Graphical The composition dependence of (a) the mexp and mth and (b) the ao and ath for the (Mn1−x Mgx)0.8Li0.1Fe2.1O4 nanosamples.

Structural investigation and physical properties of RO-ZnO-Li2B4O7-K2B4O7 (RO= SrO and BaO) glasses

Glass samples 10RO-30ZnO-xLi2B4O7-(60-x) K2B4O7 (RO=SrO and BaO) with alkali tetra borates varying from 0 to 60 mol% were produced by traditional quenching procedure. Peak free broad X-ray diffraction patterns established the amorphous feature of glass samples. FTIR and Raman spectroscopic analysis had shown existence of BO3 and BO4 structural groups along with other borate units. The BO3 ⇔ BO4 conversion rate was not much affected with variation in one of the alkali-tetraborates. EPR spectra of copper doped glasses confirmed the ground state of Cu2+ ions as 2B1g. Physical and optical properties namely density, molar volume, refractive index, molar refractivity, optical band gap and Urbach energy values were found to be composition dependent. The inflections observed in density, and other optical properties around equal mol% of alkali oxides in the glass system were attributed to structural modifications and mixed alkali effect. These results exposed the structural variations caused due to competitiveness between the two different alkali and alkaline oxides in occupying the geometrical positions of the borate glass network.

Bound exciton engineering approach for tuning the thermal lensing phenomenon in anatase TiO2: Gd nanosystems

We report a comprehensive investigation of the third-order nonlinear interaction of femtosecond laser pulses with nanostructured anatase TiO2 doped with varying concentrations of gadolinium impurities. The samples were synthesized using a facile sol‒gel method. The physicochemical characteristics of the prepared samples were investigated using various analytical techniques, including XRD, SEM, TEM, SAED, UV‒Vis, PL and XPS. The average crystallite sizes of the pristine TiO2- and Gd (1, 2, and 3 %)-doped TiO2 nanoparticles were calculated to be 10.9, 9.2, 10.2 and 8.9 nm, respectively. The W-H plots also revealed average crystallite sizes in the range of 13.9, 16.6, 13.9 and 10.4 for pristine and Gd (1, 2, 3 %)-doped TiO2 nanoparticles. The lattice strain values for pristine and Gd (1, 2, and 3 %) doped TiO2 nanoparticles were computed as 0.00203, 0.00667, 0.0036 and 0.00262, respectively, from the W‒H plots. The average crystallite size was calculated to 9.2 nm from the TEM images using ImageJ software. The optical band gap values of pristine TiO2 and Gd (1, 2, and 3 %)-doped TiO2 nanoparticles were calculated to be 3.3, 3.23, 3.21 and 3.20 eV from the Kubelka–Munk function plot. The emission peaks of pristine and Gd(1,2,3 %) doped TiO2 nanoparticles were calculated as 3.2, 3.23, 3.26 and 3.32 eV from the photoluminescence spectra recorded at 330 nm photo excitation. The binding energies of the O1s, Ti2P and Gd4d peaks present in the survey scan of TiO2 nanoparticles doped with one weight percentage of Gd impurity were 528.79, 531.53, 457.53, 463.25 and 149.6 eV, respectively. The third-order nonlinear characteristics of the TiO2:Gd samples were probed using the ultrafast laser Z-scan technique. We observed that the density of bound excitons can be regulated by controlling the dopant concentration. The strong oscillatory interactions between photogenerated bound excitons, which act as dipole oscillators with large oscillating frequencies, were recorded using a single-beam femtosecond Z-scan. The third-order nonlinear susceptibility χ(3) for pristine and Gd(1,2,3 %)-doped TiO2 nanoparticles were calculated as 7.258 × 10-18, 9.4 × 10-18, 11 × 10-18 and 13 × 10-18 cm2/V2, respectively. The obtained results suggest that the thermal lensing phenomenon in nanostructured anatase TiO2 can be generated and effectively controlled using a band gap engineering technique. We determined that the small pump power in nonlinear media with controllable band fluctuations can produce large phase distortions in TiO2:Gd nanosystems. Our findings reveal that Gd doping induces controlled modification of the electronic structure of TiO2, leading to a tailored energy landscape for exciton formation and binding. These findings provide a novel approach for engineering systems of TiO2-based nanostructures for energy-efficient optical-limiting nanophotonic systems and optoelectronic-switching devices.

Effect of synthesized copper oxide nanorods on electrical and thermal properties of compatibilized high‐density polyethylene/carbon nanofiber nanocomposite films

AbstractHigh‐density polyethylene (HDPE) nanocomposites containing different optimized fractions of carbon nanofiber (CNF) at 6 wt.%, polyethylene glycol (PEG) at 4 wt.%, and copper oxide (CuO) nanorods in concentration ranges of 0.15, 0.5, and 2 wt.% were successfully melt processed using corotating twin extrusion and compression molding technique. The effect of PEG and CuO nanofiller on the HDPE matrix were studied, particularly for the percolation threshold for electrical conductivity, structural morphology, and other properties including thermal stability, thermal conductivity (TC), dielectric, and UV protection properties. It is observed that PEG acts as a good compatibilizer, facilitating better interfacial connection between CNF and HDPE matrix. The optimized composite with 0.15 wt.% CuO nanorods (H/C6/P4/Cu0.15) shows a fine morphology and strong interfacial connections between fillers and the matrix, as observed in FE‐SEM micrographs. This optimized composite exhibits improved thermal stability, higher thermal conductivity (0.0404 W.K−1.m−1), increased dielectric constant, reduced electrical volume resistivity (from 2.1 × 1015 to 2.1 × 106 Ω.cm), and lower optical band gap value (2.74 eV). Additionally, all prepared nanocomposites offer approximately 100% Ultraviolet Protection Factor (UPF) rating for UV protection.Highlights The transformation of insulating HDPE into conducting HDPE composites. The effect of CuO nanorods was investigated in compatibilized HDPE composites. A percolation is achieved in the HDPE composite at 0.15 wt.% of CuO nanorods. PEG and CuO nanorods improved the multifunctional properties of the composite.

Exploring the Structural, Optical and Photoluminescence Performances of CuCo2O4 and ZnMn2O4 Alloying

The performance of the structural, linear/ nonlinear optical and photoluminescent properties of CuCo2O4 and ZnMn2O4 alloying was investigated. (1−x)CuCo2O4/(x)ZnMn2O4 (x = 0, 0.10, 0.15, 0.2) samples were prepared by the sol-gel and hydrothermal procedures. Synchrotron X-ray diffraction measurements were employed to investigate the structural and microstructural properties applying the Rietveld refinement method. Fourier transform infraed and Raman techniques were applied to explore the structures’ variation and chemical bonding of the obtained phases. Ultraviolet–visible diffuse reflectance spectroscopy measurements were collected to explore the optical properties. The optical band gap values were determined using the Kubelka-Munk method. All samples exhibited two band gaps in the visible-NIR regions. Upon composing with ZnMn2O4, the band gaps of CuCo2O4 declined for x = 0.1 and 0.15, followed by an increase at x = 0.2. The possible electronic band structure of the samples and the photoluminescent performance of the prepared samples was investigated. The observed PL patterns manifest wide and asymmetrical emissions. The CIE chromaticity diagram for all samples was plotted. The obtained findings of (1−x)CuCo2O4/(x)ZnMn2O4 nominate their efficient role in optical device fabrication and photocatalyst applications.

Comparative study of physical properties of As2Se3 and (As2Se3)90Ge10 glassy alloys doped with metallic impurities

To examine the compositional and chemical effects on the glassy system, one must first understand its network structure. Alloying glassy systems cause significant conformal and configurational changes. The optical and physical parameters of As2Se3 and (As2Se3)90Ge10 glassy alloys doped with metallic impurities (X = Bi, Cd, Pb, Sb) have been evaluated. A comparison of the physical properties of glassy alloys has been made as the doping elements increase, i.e., from binary to ternary to quaternary system, and an effort has been made to correlate the optical and physical parameters. The optical density (Dop) and penetration depth (δ) have been calculated from the reported absorption coefficient (α) data. The mean coordination number (<r>) and the number of floppy modes (Mf) calculations show that the floppy regions are decreasing, and hence, the rigidity is increasing when As–Se is doped with Ge and As–Se-Ge is doped with X. The density (ρ) and packing density (PD) have also been evaluated, which are interrelated to the parameters like refractive index (n) and δ. Cohesive energy (CE), mean bond energy (<E>), and glass transition temperature (Tg) values give an insight into the stability and average crosslinking of the system with alloying. The conduction and valence band potentials have supported the optical bandgap (Egopt) values variation.

Peroxymonosulphate activation by ultra-small Ni@NiFe2O4/ZnO magnetic nanocomposites for solar photocatalytic degradation of β-lactam antibiotic - cefadroxil

In this study, ultra-small nickel nanoparticles on NiFe2O4 (Ni@NiFe2O4) and Ni@NiFe2O4/ZnO magnetic nanocomposites were synthesized and utilized for the solar light-driven photocatalytic degradation of cefadroxil. The drug cefadroxil is widely used to treat bacterial infections and cefadroxil is a non-biodegradable pharmaceutical compound detected in the groundwater sources because of its low removal efficiency. The Raman active phonon at 540 cm−1 confirms the presence of Ni nanoparticles at the surface of NiFe2O4/ZnO. DR-UV-Vis analysis exhibited surface plasmon resonance at 350 nm for ultra-small nickel nanoparticles. The observed optical bandgap values for Ni@NiFe2O4 and NiFe2O4/ZnO are 1.2 eV and 2.43 eV, respectively. Which indicates that these magnetic nanocomposites can be utilized for the mineralization of cefadroxil (β-lactam antibiotic) under ambient environmental conditions. The efficiency was determined by the direct solar light driven photocatalytic oxidation of cefadroxil in the presence and absence of peroxymonosulphate (PMS). The experimental findings exhibits that ∼95 % of cefadroxil (CDL) was eliminated by the ultra-small Ni@NiFe2O4/ZnO within 60 min (k = 7.5 × 10−4 s−1) of direct solar light irradiation. Further, the addition of PMS enhanced the photodegradation to achieve 100 % cefadroxil oxidation within 40 min (k = 25 × 10−4 s−1) of direct sunlight. The efficiency of the nanocatalyst was compared with controlled experiments and was found to be Fe2O3 < ZnO < TiO2 (P25) < Ni@NiFe2O4 < Ni@NiFe2O4/ZnO under absence and presence of PMS. Moreover, ultra-small Ni@NiFe2O4/ZnO nanophotocatalyst were stable up to 3 consecutive cycles.

Influence of NiCo2O4/PbS nanocomposite on the structural, optical and electrical properties of Polymethyl Methacrylate polymer

Poly(methyl methacrylate) (PMMA)/(1-x)NiCo2O4/xPbS polymers were prepared using the casting hydrothermal and solid state reaction methods. The different phases formed in (1-x)NiCo2O4/xPbS nanocomposites were determined using the X-ray diffraction (XRD) technique. XRD and scanning electron microscopy (SEM) techniques were used to explore the structure and morphology of the formed polymers. The influence of (1-x)NiCo2O4/xPbS nanocomposite doping on the absorption, transmission, extinction coefficient, absorption coefficient, refractive index, nonlinear optical parameters and fluorescence spectra of PMMA polymer was explored using diffused reflectance and fluorescence spectrophotometer techniques. The direct and indirect optical band gap (Eg) values decreased from (5.31 and 5.06) eV (for undoped PMMA) to (4.66 and 4.17) eV (for doped PMMA with x = 0.1 filler), respectively. Several models based on the Eg value were used to find out the value of the refractive index of different polymers. The impact of doping on the dielectric constant, relaxation time, energy density, electrical conductivity and electric modulus of the PMMA polymer was also studied using an LCR meter.

Effect of annealing temperature on the structural, optical, morphological, and photocatalytic properties of TiO2 thin films prepared by sol-gel spin-coating and electron beam physical vapor deposition

TiO2 thin films were prepared by sol-gel spin-coating (SGSC) and electron beam-physical vapor deposition (EB-PVD) methods and annealed at different temperatures (Ta ). X-ray diffraction spectroscopy (XRD) results show that the TiO2 films prepared by the SGSC method transformed from the anatase single phase to the coexistence of anatase and rutile with the increase of Ta . However, TiO2 films prepared by the EB-PVD method existed only in the anatase phase, and the crystalline strength was enhanced with the increase of Ta . Meanwhile, particles of TiO2 targets annealed at different Ta showed a rutile phase for TiO2 target particles in the EB-PVD method. The results indicate that the EB-PVD method hinders the nucleation growth and phase transformation of TiO2 films. Scanning electron microscopy and atomic force microscopy also show that the grain size and R ms of TiO2 thin films prepared by the SGSC method increased with the increase of Ta , and the grain size becomes inhomogeneous when the rutile phase is formed. Ultraviolet–visible results show that the forbidden bandwidth and light absorption capacity increase with increasing Ta . For the EB-PVD method, the grain size and surface roughness gradually increased when the Ta of the films was less than 800 °C, while annealing at 800 °C changed the direction of growth and nucleation, and also produced surface cracks; XRD verified the hypothesis that the EB-PVD method hinders the nucleation growth as well as the phase transition of the films. Weak differences in the optical absorption properties and bandgap values of the films also indicate that the EB-PVD method hinders the phase transformation of TiO2 films. Finally, the results of degradation of methylene blue (MB) under simulated visible light showed that the films prepared by the SGSC method gradually improved the photocatalytic performance with the enhancement of the crystalline strength of the anatase phase. The TiO2 films prepared by the EB-PVD method improved the photocatalytic performance with the increase of the active area.

Insights into the compositional and temperature-mediated magnetic characteristics of chromium-doped ZnO nanoparticles

This study explores the influence of chromium content and temperature on the magnetic characteristics of ZnO synthesized via the cost-effective coprecipitation approach. The host ZnO structure is not significantly changed by chromium doping, even at 5 wt.% of chromium concentration, according to x-ray diffraction studies. The Zn–O characteristic stretching vibration band at 480 cm−1 and the other functional group attached to the Cr-doped ZnO nanoparticles are confirmed by Fourier-transform infrared (FTIR) spectroscopy studies. Diffuse reflectance spectroscopy analysis shows the interaction between chromium ions and ZnO causes bandgap narrowing, and the observed optical bandgap values fall as chromium content increases in the host ZnO matrix. Point defects such as zinc interstitial, zinc vacancy, and oxygen vacancy that exist in the Cr-doped ZnO nanoparticles are inveterate through photoluminescence spectroscopy. Vibrating sample magnetometry investigations reveal weak ferromagnetic behavior at low applied fields and diamagnetic signatures dominating at high applied fields in the Cr-doped ZnO nanoparticles at 300 K. The magnetic characteristics are also tunable in terms of temperatures, which opens new avenues for fabricating dilute magnetic semiconductors with various applications.

Rapid Microwave Method to Enhance the Characteristics of Fe3O4 and Fe3O4/SiO2 Nanoparticles

The application of nanoparticles can increase the number of products and protect against the deadly effects of industrial processes. Generally, nanoparticle technology offers numerous benefits, including reduced energy consumption and waste generation. Therefore, this study aimed to prepare Fe3O4 and Fe3O4/SiO2 nanoparticles using rapid microwave method. The instruments used for analysis included x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy-dispersive x-ray (SEM-EDX), and ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS). The combustion process was carried out using a microwave to produce sufficient energy for forming Fe3O4 nanoparticles. The homogeneous heating distribution process in the raw material effectively formed different initial phases and nanoparticle morphologies within a few minutes. The results showed that the application of rapid and efficient microwave provided good monodispersity, uniform core-shell structure, and high magnetization. The calculated optical bandgap values for Fe3O4 and Fe3O4/SiO2 ranged from 1.77–2.33 eV. According to magnetic analysis, Fe3O4 nanoparticles showed superparamagnetic behavior at room temperature with a value of 32–40 emu/g, while Fe3O4/SiO2 powder had 9–23 emu/g. The analysis of SEM-EDX showed that SiO2 had the potential to prevent particle aggregation and stabilize the nanoparticles prepared. Moreover, further study is recommended to modify the product with other materials, such as TiO2, for photocatalysts.

&lt;span&gt;Effect of limited oxygen gas flux on properties of Al-doped ZnO films&lt;/span&gt;

In this study, Al-doped ZnO thin films were sputter deposited on glass substrate as a function of limited oxygen gas inlet. The crystal structure, optical, and electrical properties of the films were characterized using X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, and Hall measurement. High crystallinity was found in all AZO samples. Surface morphology presented small grain size of ~ 50 – 100 nm, and thickness of AZO thin films were maintained approximately at 280 nm. Average optical transmittance of AZO films was about 90% in the 450 – 600 nm region, and optical band-gap values varied from 3.327 to 3.380 eV. The electrical resistivity of AZO films decreased with an increasing amount of oxygen flux. These AZO films are quite appropriate for the perspective development of UV photodetectors as a central role absorbing components or n-type semiconducting layers.