Decrease In Band Gap Research Articles

A Novel Turn‐On Fluorescence Probe for Selective Picomolar Detection of Uric Acid Using Green Carbon Dots (G‐NCDs) from Waste Brachyura Shells

AbstractIn the current study, a Novel synthesis of fluorescent Green carbon dots (G‐NCDs) is reported from waste Brachyura shells using a simple, green technique. G‐NCDs function as a TURN‐ON fluorescent probe for the selective detection Uric Acid (UA) in presence of Dopamine (DA). The synthesized carbon dots are sand colored under visible light and exhibit pale green fluorescence under UV radiation. The G‐NCDs are characterized using UV–vis, FTIR, XPS, SEM‐EDAX, HR‐TEM, X‐ray diffraction, and PL spectroscopic technique. The SEM‐EDAX data of G‐NCDs shows a layered, fibrous morphology and confirms the presence of only Carbon, Nitrogen, and Oxygen in the matrix. FTIR and XPS response confirms the presence of functional groups like ─C≡N, ─C≡C─, CH, ═C─H, O─H on the surface of G‐NCDs. XRD data confirms G‐NCDs to be crystalline with a particle size of 4.51 nm. The quantum yield found to be 99.8%. PL response confirms a TURN OFF fluorescence with increased addition of DA. Fluorescence resonance energy transfer (FRET), a form of dynamic quenching is responsible for the DA quenching, confirmed through linear Stern‐ Volmer plot. With increase in addition of UA in presence of DA fluorescence TURNs ON with a minimum selective detection limit of UA as 0.23 × 10−12 M. Selective detection of UA in presence of DA is due to the following reasons i) decrease in bandgap of G‐NCDs in presence of UA ii) electrostatic attraction between negatively charged carboxyl group of G‐NCDs and positively charge secondary amine group of UA molecule ii) UA molecules near to the surface of G‐NCDs switches off the formation of polydopamine iv) formation of surface defects due to the formation of hydrogen bonds between the ketone/hydroxyl group in the UA molecule and the amino group on the surface of G‐NCD resulting in fluorescence. The first time the lowest detection limit of 0.23 × 10−12 M of UA is been reported in presence of DA using G‐NCDs. In future, G‐NCDs will be used for the detection of UA in biological fluids.

Strain induced crystal lattice softening and improved thermoelectric performance of hydrogenated silicene for energy harvesting applications

In recent years, Silicene has attracted great interest in various fields but does not fit well in the field of thermoelectrics due to the absence of electronic band gap. Nevertheless, hydrogenation of silicene (SiH) delocalize the free electrons and induces gap widening (2.19 eV), but its thermoelectric performance is still limited due to the larger band gap. Thermoelectric performance can be effectively improved using strain engineering, which allows modulation of crystal as well as electronic energy levels of a material. We studied the effect of biaxial tensile strain on structure, stability and thermoelectric properties of SiH monolayer. Taking clue regarding the stability from phonon dispersion, tensile strain upto 14% is incorporated and results are discussed. The distortion of crystal structure with strain manipulates the characteristics of electronic band structure such that there is an indirect to direct band gap transition along with decrease in band gap, effective mass and relaxation time of carriers. As a result, the Seebeck coefficient falls and attains minimum value at 14% strain while electrical conductivity and electronic thermal conductivity shows increasing trend and maximize at 14% strain. Another crucial consequence of strain is that tensile strain led to a considerable decrease in lattice thermal conductivity. At a strain of 14%, the lattice thermal conductivity at 700 K (0.28) decreased by approximately 43% compared to its unstrained counterpart (0.49 K), which is highly beneficial for achieving high ZT. To assess the efficiency of thermoelectric conversion, the ZT is computed, revealing an increase from 1.66 in the unstrained state to 2.83 at a strain of 14% and a temperature of 700 K. The calculations unveil a nearly twofold increase in ZT with the implementation of strain engineering, underscoring its effectiveness in augmenting the efficiency of thermoelectric devices.

Experimental and computational study of Bi2O3/WO3 heterostructures as efficient solar driven photocatalyst

Industrial wastewater is always a matter of challenge, polluting the environment and ultimately causing a hazardous effect on human beings and various other species. For the elimination of these pollutants, in this study, we synthesized Bi2O3 nanoparticles and Bi2O3/WO3 heterostructures by chemical co-precipitation method and investigated their photocatalytic activity for the degradation of methylene blue (MB) under solar light irradiation. The synthesized nanoparticles were characterized by various analytical techniques, including X-ray diffraction (XRD), Scanning-electron-microscopy (SEM), Fourier-Transform-Infrared Spectroscopy (FTIR), and UV–Vis. absorption Spectroscopy. Results of this study revealed that the pure Bi2O3 sample has a band gap of 3.5 eV, however, Bi2O3/WO3 heterostructure exhibited a reduction in band gap to 3.1 eV. The decrease in band gap significantly enhanced absorption of solar light, which correlated with an increase in photocatalytic activity as Bi2O3/WO3 nanocomposite degraded 81.5 % of MB in 240 min, while pristine Bi2O3 only degraded 58.7 % of the MB in the same period. The enhanced photocatalytic performance of the nanocomposite can be attributed to the synergistic action between Bi2O3 and WO3, which enhances the production of reactive oxygen species (ROSs) and the efficiency of charge separation, thus promoting the degradation of MB. A type-II heterostructure has been proposed to enhance the separation of charge carriers. Moreover, our computational study supported these findings, indicating a decrease in trends of the band gap of heterostructure as compared to pristine Bi2O3. The results of this study highlight the potential of Bi2O3/WO3 nanocomposites as promising materials for environmental remediation applications, particularly for the efficient removal of organic pollutants from wastewater under solar irradiation.

Fabrication of CuS-MoO3 nanocomposite for high-performance photocatalysis and biosensing

The design and development of highly efficient nanostructure materials for photocatalytic and electrochemical applications is very necessary. In this study, CuS-MoO3 nanocomposite (NCs) was fabricated using a simple wet impregnation process and the photodegradation potential for 8 major hazardous dyes and electrochemical sensing of Dopamine was investigated. X-ray diffraction (XRD), Fourier transform - Infrared spectroscopy (FTIR), UV-Vis spectroscopy (UV-Vis), Photoluminescence spectroscopy (PL), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Transmission Electron Microscopy (TEM) were employed for characterization. Fabricated NCs are made up of CuS in the hexagonal phase and MoO3 in the orthorhombic phase, both of which react to UV light. Optical and electrochemical impedance spectroscopy (EIS) results show that improved photocatalytic performance is related to increased UV light spectrum sensitivity, inhibited charge carrier recombination, and decreased band gap energy in the NCs. Experimental findings showed that CuS-MoO3 (CMS) NCs had substantially more photocatalytic degradation activity than pure MoO3 and CuS nanoparticles (NPs). The prepared CMS NCs were then used for electrochemical analysis of Dopamine (DA). Electroanalytical results showed that the CMS NCs had enhanced electrochemical activity towards DA. The constructed sensor has a limit of detection of (6.61 µM) and proved that it is capable of being a sensor.

Comparative performance analysis of unmixed and mixed metal oxide sensors for dual-sensing leveraging machine learning.

This paper presents the synthesis of mixed metal oxide (BaTiO3: ZnO) (B: Z) sensors with various molar ratios using a low- temperature hydrothermal method for dual sensing applications (gas and acceleration). The sensor developed with an equal molar ratio of 1B:1Z, showcases superior performance compared to unmixed and alternative mixed metal oxide sensors. This equilibrium in ratios optimally enhances synergistic effects between elements B and Z, resulting in improved sensing properties. Furthermore, it contributes to structural stability, enhancing performance in gas and acceleration sensing. A decreased band gap of 2.82eV and a rapid turn-on voltage of 0.18V were achieved. The acceleration performance of 1B:1Z sensor exhibits a maximum voltage of 2.62 V at a 10 Hz resonant frequency and an output voltage of 2.52 V at 1 g acceleration, achieving an improved sensitivity of 3.889 V/g. In addition, the proposed gas shows a notable sensor response of ~63.45% (CO) and 58.29% (CH4) at 10 ppm with a quick response time of 1.19s (CO) and 8.69s (CH4) and recovery time of 2.09s (CO) and 8.69s (CH4). Challenges in selectivity are addressed using machine learning, employing various classification algorithms. Linear Discriminant Analysis (LDA) achieves superior accuracy in differentiating between CO and CH4, reaching 96.6 % for CO and 74.6 % for CH4 at 10 ppm. Understanding these concentration-dependent trends can guide the optimal use of the sensors in different current applications.&#xD.

Biofabrication and Characterisation of Ni‐Doped SnO2 Nanoparticles With Enhanced Cytotoxicity, Antioxidant, Antimicrobial and Photocatalytic Activities

ABSTRACTThe present work focuses on Annona muricata leaf extract–mediated green synthesis of pure and nickel‐doped tin oxide nanoparticles for 3%, 5% and 7% concentrations. The properties of the obtained nanoparticles were investigated through XRD, FTIR, XPS, HRTEM–SAED, SEM–EDX and UV–visible spectroscopy techniques. The XRD pattern reveals all samples have tetragonal structures with high crystallinity. The Sn–O stretching vibration has been confirmed through FTIR spectra. The XPS results demonstrate that Sn0.93Ni0.07O2 nanoparticles have Sn3d, Ni2p and O1s oxidation states. EDX spectra contain Ni, Sn and O elements, which indicate the purity of the samples. UV–visible absorption spectrum shows decreases in optical energy bandgap with increases in nickel dopant concentration. The samples exhibit notable antibacterial activity against P. aeruginosa and S. aureus. Also, Sn0.93Ni0.07O2 nanoparticle has higher antifungal activity against A. niger than against C. albicans. Moreover, SnO2 nanoparticles have considerable antioxidant activity in DPPH scavenging compared to Sn0.93Ni0.07O2 nanoparticles. Furthermore, SnO2 nanoparticles have a better cytotoxic effect for L929 normal fibroblast cell lines with an LD50 value of 146.42 μg/mL. Additionally, the photocatalytic activity of SnO2 and Sn0.93Ni0.07O2 nanoparticles was done against methylene blue dye under direct sunlight irradiation. Overall, environmentally friendly synthetic pure and Ni‐doped SnO2 nanoparticles can be used in wastewater filter technologies as well as in medical aids due to their better cytotoxic, antioxidant and antimicrobial effects.

Growth Phenomena and Bandgap Shift in Melt‐Grown β‐(InxGa1−x)2O3 Alloys

β‐Ga2O3 is an emerging ultra‐wide bandgap semiconductor with great promise for power electronics and optoelectronics. Alloys in the In2O3‐Ga2O3 system are interesting for optoelectronic applications, particularly where bandgap tuning is desirable. Herein, β‐(InxGa1–x)2O3 alloys with target compositions x = 0.025 or 0.10 are grown from the melt using the Czochralski and vertical gradient freeze techniques. Growth with 10 mol% In yields only small, needle‐like crystals, while 2.5 mol% In allows growth of centimeter‐sized single crystals. A substantial degree of indium segregation is unveiled by spatial measurements of lattice parameters and the bandgap. The bandgap decreases by a maximum of 0.28 eV in the case of the highest In content crystals. Z‐contrast transmission electron microscopy confirms a solely octahedral coordination of In in the β‐Ga2O3 lattice. With indium concentrations higher than 2.5 mol%, samples contain micron‐scale voids that impart a dark coloration. All measured crystals are electrically conductive, with carrier concentrations varying 1016–1017 cm−3 depending upon the location of the sample in the growth. Lastly, a unique luminescence with unknown origin centered around 2.0 eV is revealed by photoluminescence spectroscopy.

Hydrogen adsorption on zinc-terminated ZnO(0001) surface at varying coverages and its effects on electronic and optical properties: a DFT+U study

Abstract Spin-polarized density functional theory implementing Hubbard corrections (DFT + U) were utilized to study H adsorption of different coverages on Zn-terminated ZnO(0001) surface. Changes in electronic and optical properties were observed upon H adsorption of varying coverages, namely with 0.25 monolayer (ML), 0.50 ML, 1 ML, and 2 ML coverage. In terms of surface structure, H atoms were found to adsorb on top of Zn forming Zn–H bond lengths ranging from 1.54–1.73 Å for certain coverages. On the other hand, O–H bond length values are 2.41 Å and 2.37 Å for 0.50 ML and 2 ML coverage respectively. Additionally, for 0.50 ML, the most stable configuration is when one H atom adsorbs on top of Zn and the other near the hollow site. At low coverage (0.25 ML and 0.50 ML), H prefers to interact with topmost layer Zn atoms resulting to shifts in the electronic bands relative to the pristine surface’s. In addition, at high coverage (1 ML and 2 ML), shifting of bands are observed and are mainly guided by Zn–H atom interaction for 1 ML and weak H–O atom interaction for 2 ML. The observed decrease in band gap as the coverage was increased from 1 ML to 2 ML is supported by the red shift in the absorption plot. However, for low H coverage adsorption, the optical plots deviate due to emergence of flat bands. Changes in electronic properties such as shifts in conduction band minimum and decrease in measured band gap occur as guided by the interaction of adsorbed H atoms with the surface atoms and are supported with obtained optical plots. These findings present the tunability of Zn-terminated ZnO(0001) polar surface properties depending on H coverage.

Investigations of optoelectronic and scintillating properties of novel halide perovskites Cs2KSnX6 (X=Cl, Br, I)

In this paper, using density functional theory (DFT) formalism, optoelectronic properties of new halide perovskites Cs2KSnX6 (X = Cl, Br, I) are explored. The lattice constants of these double perovskites with Cl,Br, and I were found to be 11.75Å,12.34Å, and 13.24Å, respectively. Trans-Blaha modified Becke-Johnson (TB-mBJ) exchange-correlation functional was used to calculate the energy bandgap by incorporating spin-orbital coupling effects into it. The double perovskite with Cl was observed to possess a higher band gap value due to the increase in the size of halide anions. Due to the inverse relationship between bandgap values and lattice constants, it has been observed that increasing the lattice constant value results in the decrease of the electronic band gap and vice versa. From the density of states calculations, the nature of the electronic states involved in forming the energy bands has been determined. The upper light yield (LY) with the limit of 100 % under ideal conditions is found to be 544217 ph/MeV, 950118 ph/MeV, and 1600000 ph/MeV for Cs2KSnCl6,Cs2KSnBr6, and Cs2KSnI6 respectively, which suggests their potential applications in scintillating devices. Moreover, the optical properties like complex dielectric functions, absorption coefficients, reflectivity, and refractive index are calculated for these new proposed compounds. A systematic analysis of the optical and scintillating properties suggests the usefulness of Cs2KSnI6 among other compounds, as a potential candidate for high-energy radiation detection and other optoelectronic applications.

Effect of oxygen vacancies on enhancing the photo-catalytic activity, photo-luminescence and electronic structure properties of nanostructured Y-doped CeO2

The exceptional characteristics of CeO2 and Ce1-xYxO2 (x = 0.03, 0.05 and 0.07) nanoparticles were reported in the manuscript supporting that Y3+replaces Ce3+/Ce4+leads to oxygen vacancies formation. The results of XRD measurements revealed FCC structure of decreased crystallite size of CeO2 with improved crystallinity. To investigate the surface morphology, HRTEM and SAED patterns were performed. EDX analyses were undertaken to discuss the elemental and compositional characteristics. The absorption spectra using UV–Vis–NIR spectroscopy were analyzed and red shifted absorbance was found to enhance with decreasing band gap values for increased Y doping. The Photoluminescence spectra depicted various emissions representing the development of various defects and oxygen vacancy with incorporation of Y content in the lattice with CCT values below 4000 K to be classified as warm yellow light for indoor applications. The development of oxygen vacancies in the CeO2 lattice was further supported by XPS measurements for core levels Ce 3d, O 1s and Y 3d. Furthermore, the XPS measurements also reported the valence states of elements, Ce with 3+ and 4+, Y with 3+ and O with 2- along with charged oxygen vacancies. The photo-catalytic analysis revealed that Y-doped CeO2 nanoparticles show better degradation using a variety of characterization. A degradation mechanism that illustrates the impact of oxygen vacancies created by Y-doping on the photo-degradation process has been proposed. The novelty of Y-doped CeO2 nanoparticles stems from their improved photo-catalytic activities, which are linked to structural changes and the formation of oxygen vacancies. This doping considerably affects the electrical structure, resulting in better light absorption and less electron-hole recombination. The detailed outcomes of present study suggested the use of Y-doped CeO2 nanoparticles in optoelectronics, spintronics devices and photo-catalyst applications.

Enabling Fast‐Charging and High Specific Capacity of Li‐Ion Batteries with Nitrogen‐Doped Bilayer Graphdiyne: A First‐Principles Study

AbstractCarbon‐based materials are the most important anode materials for Li‐ion batteries (LIBs). To improve the electrochemical performance of LIBs for high energy density and fast charging, advanced carbon allotropes are in the research focus. In this work, we applied the density functional theory to investigate the atomic and electronic structures as well as high Li‐ion specific capacity of graphdiyne (GDY). The atomic structures of monolayer graphdiyne (MGDY), bilayer AB(β1)‐stacking graphdiyne (AB(β1)BGDY) and nitrogen‐doped AB(β1)BGDY (N‐AB(β1)BGDY) at different lithiation states were thoroughly investigated. The AB(β1)BGDY and N‐AB(β1)BGDY exhibit promising characteristics in Li‐ion adsorption and intercalation, enhancing its specific capacity from 744 mAhg−1 in the monolayer GDY to 807 mAhg−1 in the bilayer. Besides increasing the capacity through a bilayer‐structure, it is possible to tailor its structural stability and band gap by doping. Especially shown for N‐AB(β1)BGDY (~1 %), an increased structural stability and a decreased band gap of 0.24 eV is found. While this means that N doping in AB(β1)BGDY can lead to longer‐lasting and more stable operatable high‐capacity anodes in LIBs, it increases the open‐circuit voltage (OCV).

Wave Function Localization Reduces the Bandgap of Disordered Double Perovskite Cs2AgBiBr6.

Double perovskite Cs2AgBiBr6 is a promising alternative to lead-based perovskites with excellent stability and attractive optoelectronic properties. However, a relatively large bandgap severely limits its performance in many applications such as solar cells and photodetectors. It has been reported that a random distribution of Ag and Bi atoms in Cs2AgBiBr6 effectively reduces its bandgap without introducing dopants or impurities, while the mechanism remains unclear. Here, using density functional theory calculations, we demonstrate that the Ag-Bi disorder in Cs2AgBiBr6 generates localized electronic states as band edges to regulate the bandgap. The disordered structures segregate Ag and Bi atoms in the lattice, and the formed homoatomic clusters lead to wave function localization. Moreover, the bandgap decrease exhibits a non-monotonic dependence on the degree of disorder. Our results are comparable with experimental observations and provide crucial insights into understanding the order-disorder transition in double perovskites.

Crystallization and phase transition boosted optical linear& nonlinear and magnetic properties in transparent xCu: BaSnO3 NCs/glass-ceramic

In this study, cubic xCu: BaSnO3 (x = 0, 1, 3, and 5 mol%) perovskite nanocrystals were synthesized using a hydrothermal method. The influence of Cu doping levels on the crystal structure, morphology, size, and properties was analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Raman, Ultraviolet-Visible Spectroscopy (UV–vis), Vibrating Sample Magnetometry (VSM), and X-ray Photoelectron Spectroscopy (XPS) techniques. Across the 1–5 % doping range, the cubic BaSnO3 structure was maintained with Cu2+ in CuO6 replacing Sn4+ in the B-site. XPS analysis confirmed the formation of oxygen vacancies due to charge imbalance, leading to a decrease in optical bandgap and an increase in ferromagnetic moment. When various contents of xCu: BaSnO3 were doped into borosilicate glass, significant impacts on the glass network, crystallization, and properties were observed. Nanocrystals (∼50 nm) transitioned from cubic to orthorhombic phase beyond 3 mol% doping, modifying the glass network by converting BO3 to BO4, AlO4 to AlO6, and CuO6 to CuO4. This phase change endowed the glass's strong ferromagnetic moment and absorption due to the t2 g→eg transitions of Cu2+ in CuO6, and reduced the optical bandgap from 3.16 to 2.2 eV. The glass also exhibited improved Vickers hardness (475 HV) and a high Verdet constant of 0.174 min/G·cm due to network modifications. Glass also shows a distinct red emission at 596 nm with a 160 µs lifetime and good thermal stability, while doping levels above 3 % resulted in emission quenching. The optical nonlinear absorption coefficient and nonlinear susceptibility increased with higher doping levels, reaching huge values of α3: 5.12×10−10 m/W and χ(3): 7.52×10−10 esu, indicating potential for self-focusing applications. The increased polarizability also resulted in a high dielectric constant (18) and a large P-E loop of glasses which are promising for advanced photonics devices.

TM@MoSSe (TM = Ni, Fe) as novel electrocatalysts for reduction of CO2 to CO: A DFT study

It is crucial to develop highly efficient, selective and low-overpotential electrocatalysts for CO2 reduction. This paper proposes an efficient iron and nickel single-atom catalyst using Janus MoSSe as the substrate to reduce CO2 to CO by using DFT calculations. The adsorption of a single TM atom like Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt on Janus MoSSe monolayer results in a decrease in band gap, which may accelerate the catalytic CO2 reduction. The excellent catalytic activity of Fe@MoSSe and Ni@MoSSe is owing to the high d-band center and hence the strong TM-CO2 bonding. The asymmetric structure of Janus MoSSe creates the local built-in electric field, which further increases by about 8% or 0.8% after the adsorption of single Ni or Fe atom so as to afford the better electrocatalytic performances for reduction of CO2 to CO in both TM modified systems. So, this work proposes the catalysts Fe@MoSSe and Ni@MoSSe with good selectivity and activity for CO2 reduction by revealing their underlying mechanisms, and Janus MoSSe may be used as a potential substrate material for CO2 reduction catalysts.

Sulphanilamide degradation by undoped and copper doped ZnO, and ferromagnetic properties of fresh, aged, and heat-treated aged ZnO

This work looks into how well Cu-doped zinc oxide works as a photocatalyst when exposed to visible light to break down sulphanilamide. The synthesized samples were characterized by XRD and then FTIR techniques for structural besides compositional analysis. The approximate value of bandgap found out by NBE values of PL spectra showed a decrease in bandgap with doping. Deconvoluted PL spectra revealed the presence of radiative recombination pathways associated with zinc interstitial and zinc vacancy in addition to band-to-band recombination in all samples. FESEM images showed a nanoflake shape for pure ZnO, while Cu-ZnO had a pseudo-spherical shape. SQUID-VSM was adopted to understand the magnetic nature of freshly prepared, heated, and unheated aged samples. Ferromagnetic behavior was observed with saturation magnetization of 5.56×10–4, 2.88×10–4, and 2.78×10–4 emu/g for freshly prepared, heated, and unheated aged samples, respectively. A 2% Cu-doped sample exhibited the highest efficiency of 92.3% towards the degradation of sulphanilamide. Since we got better efficiency for 2% Cu-ZnO, we should further decrease the doping percentage and check whether we will get even higher efficiency in the future. The photocatalytic degradation efficiency of ternary ZnO compounds, codoped ZnO, should be evaluated, yet another future scope.

Structural and optical evolution in CeO2 films induced by aluminum doping: A comprehensive study

This study investigates the impact of aluminum (Al) doping and oxygen vacancies on the structural, electronic, and optical properties of Cerium Oxide (CeO₂) films. The films were fabricated on glass substrates using the sol-gel spin coating method for both undoped and Al doped CeO₂. Theoretical insights from the DFT + U + V method further explore how Al doping and oxygen vacancies influence the electronic structure and optical behavior of ceria. Experimentally, Al doping was found to increase the lattice parameters and reduce the crystallite size without forming secondary phases. Raman spectroscopy revealed a shift to lower wavenumbers in Al-doped samples, while XPS analysis confirmed the presence of both Ce³⁺ and Ce⁴⁺ oxidation states, along with Al³⁺ and O2⁻ ions. Optical measurements showed a decrease in the optical band gap from 3.14 eV to 2.93 eV as the Al concentration increased to 5 %. Additionally, the optical dielectric constant slightly decreased, whereas optical conductivity improved with the incorporation of aluminum. Theoretical calculations show that oxygen vacancies were shown to reduce the band gap by introducing localized Ce³⁺ mid-gap states, while Al doping led to a gradual narrowing of the band gap without creating new states within it. The combination of Al doping and oxygen vacancies resulted in both further band gap narrowing and the appearance of mid-gap states. Optical property calculations revealed that both oxygen vacancies and Al doping reduced the intensity of the dielectric functions at 310 nm. Moreover, these two factors had opposing effects on the electron energy loss spectrum (EELS) at low energies: Al doping induced high-intensity peaks, while oxygen vacancies diminished these peaks.

Effect of B/Pb ion replacement in B2O3-PbO-SiO2 glasses: Structural, thermal, optical and electrical properties

Due to its easy manufacturing process and outstanding physical and chemical characteristics, boron lead silicate glass is widely used in electronic packaging, optical fields, and sensor technology. Herein, new glass samples with different proportions of B2O3/PbO are prepared by a combined melting and annealing process. The glasses undergo structural and thermal characterization to investigate its composition, thermal behavior, optical properties, and dielectric properties. The results show that the glass structure changes gradually as [SiO4] and [PbO4] units were replaced by [BO3] units with increasing B2O3 content. This transformation has an impact on coefficient of thermal expansion and characteristic temperature of the glass. Additionally, it is observed that alterations in structure resulted in a decrease in both optical band gap as well as dielectric constant and loss. These findings provide insights into how variations in the B2O3/PbO ratio influence structural evolution and enhance properties for boron lead silicate glasses. This provides a theoretical basis for further advances to improve material properties and expand optical and electronic applications.

Investigating the influence of RF power on the surface morphological and optical properties of sputtered TiO2 thin films

Thin films of titanium dioxide (TiO2), with thicknesses ranging from 105 to 231 nm, were deposited on glass substrates using radio-frequency (RF) magnetron sputtering in an argon atmosphere at four distinct RF power levels: 40, 70, 100, and 130 W, with the deposition time kept constant. The crystalline structure, surface morphology and optical and semiconductor properties of the obtained films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and UV–visible transmittance spectroscopy. These analyses revealed that the crystallinity of the films improves with increasing RF power, corresponding to an increase in film thickness. Consequently, the samples transition from poorly crystalline or amorphous structure to a monocrystalline rutile phase with a (110) texture. However, at the highest RF power studied, this texture is partially disrupted by the formation of nanocrystals with different orientations. The surface roughness exhibited multifractal characteristics, with complexity systematically decreasing and surface stiffness reducing as RF power increased. Refractive indices and optical band gap energies were determined using the Swanepoel and Tauc plot methods, respectively. The films exhibited a notable increase in the refractive index and a decrease in the optical band gap, from 3.81 eV to 3.52 eV, as the RF power was increased. This underscores the influence of RF power on the optical and semiconductor properties of TiO2 films.

Influence of transition metal (Cu) and rare earth metal (Dy) co-doping on spinel zinc ferrite (Cu0.1Dy0.08Zn0.9Fe1.92O4) for improved photocatalytic degradation of industrial effluents

In the present era, design and development of novel, highly stable, easily and magnetically separable, cost effective, and visible light driven catalytic material for the removal of harmful industrial effluents is of great importance. In this context, facile co-precipitation route was adopted for the synthesis of ZnFe2O4 (ZFO), Cu0.1Zn0.9Fe2O4 (CZFO), Dy0.08ZnFe1.92O4 (DZFO), and Cu0.1Dy0.08Zn0.9Fe1.92O4 (CDZFO) and their fabrication was confirmed by XRD, FTIR, SEM, and UV-Visible spectroscopy. The phase analysis of all designed materials exhibits that there is an increment in the crystallite size of co-doped zinc ferrite (CDZFO) i.e. 11.51 nm as compared to ZFO (10.74 nm), CZFO (10.92 nm), and DZFO (11.41 nm). The optical study shows a significant decrease in bandgap of CDZFO i.e. 1.82 eV as compared to DZFO (1.89 eV), CZFO (2.0 eV), and ZFO (2.14 eV). This decrease in optical bandgap and increase in crystallite size of the CDZFO is due to the quantum confinement effect. The photocatalytic efficiency of pure, doped, and co-doped samples was investigated against organic dye (Congo red), pharmaceutical drug (ibuprofen), and colorless organic compound (benzoic acid). The photocatalytic results reveal that CDZFO showed about ∼90 % degradation of Congo red while ZFO, CZFO, and DZFO showed only 59 %, 70 %, and 79 % respectively. Moreover, CDZFO also showed highest photocatalytic removal efficiency against ibuprofen (88 %) and benzoic acid (74 %) out of all other synthesized materials. The remarkable photodegradation ability of CDZFO for all targeted pollutants could be attributed to the generation of crystal defects in its lattice, its small bandgap, and higher absorption in visible region. Furthermore, the recyclability experiment confirmed the stability and reusability of the prepared sample.

Effects of Pt doping on surface properties and quenching of band edge emission in ZnO

Pt doped ZnO thin films were synthesized on soda-lime glass substrates using a cost-effective sol-gel method, followed by spin coating and thermal annealing at various temperatures. Several characterization techniques such as UV–Vis absorption spectroscopy, photoluminescence (PL), field emission scanning electron microscopy (FESEM), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) are exploited to investigate the Pt doping effects on surface and optical properties of ZnO thin films. UV–Vis analysis demonstrated a slight decrease in the optical band gap from 3.3 eV to 3.2 eV with increased annealing, indicating enhanced suitability for optoelectronic applications. FESEM imaging revealed distinct worm-like structures and small Pt metal nanoparticles in unannealed samples, while thermal treatment supported the formation of spherical Pt nanoparticles and improved conductive pathways in the films. The Wagner diagram, coupled with Auger line transitions from XPS, quantified the oxidation states and chemical environments of Zn and Pt, respectively. Notably, the observed changes in the binding energy of the Zn-2p junction and the kinetic energy of the Zn-LMM Auger junction were significantly influenced by the Pt doping and the electronic properties of the substrate. The Wagner diagram provided a comprehensive visual representation of the parameters, facilitating a deeper understanding of electronic interactions and structural dynamics at the atomic level. XPS results confirmed the presence of ZnO, Zn(OH)2, Pt0 and PtO2 phases, indicating stability and constutient's interactions. ToF-SIMS also validated the uniform distribution of Pt nanoparticles within the ZnO thin film, confirming the effectiveness of the sol-gel method. As a result of Pt doping, PL studies revealed a large quenching effect on band edge emission in the UV and visible emission region of ZnO thin film, which is due to Pt acting as a recombination center for photogenerated carriers. Overall, our results highlight the influence of annealing and Pt incorporation on the optical and structural properties of ZnO thin films and highlight their potential applications for photonics and catalysis.