Combustion Technique Research Articles

EFFECTS OF SYNTHESIS TEMPERATURE ON THE STRUCTURAL AND OPTICAL PROPERTIES OF CaAl2O4: Eu2+, Dy3+NANOPARTICLES

Calcium aluminate phosphor nanomaterials co-doped with europium and dysprosium (CaAl2O4: Eu2+, Dy3+) were prepared using a facile solution combustion technique. The structural and optical properties were investigated. The X-ray diffraction (XRD) results confirmed the presence of the monoclinic phase in all the samples, with few impurity phases in the samples synthesized at 300°C and 400°C. The Fourier-transform infrared analysis gave the expected chemical combustion results of the final product with few traces of Ca3Al2O6 impurities at low and very high synthesis temperatures. The XRD patterns displayed diffraction angles of the major peaks shifting to higher 2 theta as the synthesis temperature increased. This is attributed to an increase in particle sizes, which led to an increase in lattice parameters. The intensity of the prominent peak increased up to 500°C due to improved crystal quality. The crystallite sizes of the as-prepared samples were determined using the Debye-Scherrer equation. It was noted that there is variation in the crystallite sizes with synthesis temperature. The UV-Vis graph shows that absorption edges also shifted to lower wavelengths with an increase in synthesis temperature. It was noted that the band gap increased with an increase in synthesis temperature up to 500°C, but at temperature of 1000°C, the band gap was observed todecrease. Scanning electron microscope micrographs showed that the samples had irregular shapes with pores and cracks. The study provides a simple route to synthesize CaAl2O4: Eu2+, Dy3+ phosphors with optimum synthesis temperature, producing the most crystalline sample for use in lighting devices.

One-Pot Synthesis and Characterization of Magnetic α-Fe2O3/CuO/CuFe2O4 Nanocomposite for Multifunctional Therapeutic Applications.

This study demonstrates a novel nanostructured drug delivery system utilizing α-Fe2O3/CuO/CuFe2O4 ternary nanocomposite for effective drug transport in sick tissues. Centella Asiatica plant extract was employed to synthesize the Fe2O3/CuO/CuFe2O4 nanocomposite via sol-gel auto combustion technique. The structural and morphological characteristics of the nanocomposite were investigated by XRD, FT-IR, SEM, EDX, and VSM for magnetic properties. The XRD analysis demonstrates the successful synthesis of Fe2O3/CuO/CuFe2O4 nanocomposite with an average crystallite size of 18.393 nm. The antioxidant and antifungal capabilities of this nanocomposite were assessed for its biological activity. A notable inhibitory zone was observed when tested against the Alternaria spp. and Bipolaris sorokiniana fungi. An IC50 value of 109.88 μg/ml was found in the DPPH test, indicating that the nanocomposite exhibited remarkable antioxidant characteristics. Subsequently, metronidazole was encapsulated with a success rate of 55.53 % at pH 1.2, while at pH 7.4 it gained 57.83 %. The drug release of nanocomposite at pH 1.2 after 330 min was 43.41 % and at pH 7.4 after 300 min it was 52.3 %. The results indicate its potential as an excellent candidate for drug delivery. Furthermore, pH was found to be an effective catalyst in the drug loading and release processes.

In-vitro biomineralization of magnesium and copper co-doped wollastonite

Calcium silicate-based ceramics, particularly wollastonite (CaSiO3), are gaining prominence in hard tissue engineering due to their biocompatibility and bioactivity. However, pure wollastonite faces challenges such as insufficient mechanical strength and susceptibility to bacterial colonization. This study addresses these issues by systematically synthesizing magnesium and copper co-doped wollastonite (MgCuW) using the sol-gel combustion technique, aiming to enhance its mechanical stability and antibacterial properties. The average crystalline size of the synthesized materials ranged from 25 to 47 nm. In vitro biomineralization studies showed significant hydroxyapatite deposition, confirming enhanced bioactivity. Antibacterial tests against Gram-positive (S. aureus, S. epidermidis) and Gram-negative (E. coli, P. aeruginosa) bacteria demonstrated superior antibacterial activity with increased copper doping. The results indicate that MgCuW is a promising biomaterial for bone tissue engineering, combining bioactivity and antibacterial efficacy.

Hydrographic restriction conditions in the Middle and Upper Yangtze region during the Early Silurian post-glacial transgression: Constraints from major, trace elemental geochemistry and Mo-TOC relationship

Redox-sensitive trace metals have not only been widely used as the proxy for palaeoredox potential due to the strong enrichments under reducing conditions but also provide critical information into water-mass properties, such as the degree of basin restriction. In order to reveal the Early Silurian post-glacial transgression hydrographic restriction conditions throughout the Middle and Upper Yangtze region, trace metal concentrations and organic geochemical data of the lower Longmaxi Formation were analyzed by the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Leco combustion techniques. We analyzed the hydrographic restriction conditions and redox conditions of different depocenters, including the Southern, Eastern, and Northern Sichuan Basin depocenters and the Western Hubei Region depocenter. The sedimentary Mo-TOC relationship, MoEF-UEF covariation, and upwelling intensity suggest that the Southern, Eastern Sichuan Basin depocenters and the Western Hubei Region depocenter were deep water areas with moderate hydrographic restriction, whereas the restriction conditions of Northern Sichuan Basin depocenter was relatively weak. In addition, due to the combined effect of geographical location, connectivity with the open Qinling Ocean, and estuarine circulation, restriction degrees varied in the same depocenter. The redox proxy (Corg/P) indicated that the lower Longmaxi Formation was deposited in an anoxic water column. There are significant spatial differences in redox conditions in different depocenters and different locations within the same depocenter, which may be controlled by relative sea level rise, hydrographic restriction, and upwelling intensity. Anoxic conditions were more likely to occur in areas where water column was relatively deep and restricted. In addition, the anoxic conditions in the Northern Sichuan Basin depocenter may also associated with the strong upwelling intensity and the behavior of P cycling back to water column, which can promote the primary productivity and further maintain persistent anoxic conditions. The correlation between Corg/P and Mo/TOC indicates that, in relatively weak restriction basin, the trace elements enrichment in sediments was controlled by trace elemental concentrations in seawater. In moderate restriction basin, the trace elements enrichment was mainly controlled by redox conditions. Whereas under more reducing conditions, hydrographic restriction may tend to become the dominant factor. The application of sediment Mo-TOC relationship, MoEF-UEF covariation, and upwelling can provide insights into hydrographic restriction conditions, but the Mo/TOC relationship is limited to anoxic facies, as little trace metal accumulation could also be the consequence of oxic conditions.

Designing Tb-doped Mn-Ni-Cu ferrite meta-absorbers for a broad frequency range: Magnetodielectric, physical, reflection loss, and absorptivity characteristics

Developing meta-absorbers with exceptional EM wave absorption, shielding capacity, and superior dissipation performance remains worthwhile in the gigahertz (GHz) range. Electromagnetic pollution has a detrimental impact on the health of living organisms due to the emergence of high-frequency waves from communication devices. The challenges were addressed by preparing, designing, and simulating ferrite-based meta-absorbers. The nanoferrites of Tb-doped Mn-Ni-Cu (Mn0.2Ni0.3Cu0.5TbxFe2-xO4) with different levels of Tb (x = 0.00, 0.025, 0.05, 0.075) were prepared utilizing the sol-gel auto combustion technique. The phase, structural, elastic, and magnetic features of the Tb-doped Mn-Ni-Cu ferrites were examined using XRD, FESEM, FTIR, and VSM techniques, respectively. The MAUD software was utilized to obtain refinement and precise structural characteristics. The force constant, phase, and elastic properties were also assessed. The magnetization and coercivity exhibited a reduction. An assessment was conducted on the performance of field switching and high-frequency response. At high frequencies, the dielectric characteristics, such as complex permeability and permittivity, exhibit greater values, while losses diminish. At a frequency of 4.6 GHz, a reflection loss (RL) of −54.21 dB was measured for x = 0.05, whereas a reflection loss of −54.03 dB was measured for x = 0.075. The meta-absorbers of Tb-doped Mn-Ni-Cu ferrites were designed and simulated. The absorptivity of the Tb-doped Mn-Ni-Cu ferrite substrate material is illustrated. The meta-absorber exhibited three distinct absorption peaks at frequencies of 1.5, 2.5, and 4.5–6 GHz, respectively. The absorptivity of the material likewise rises with an increase in the incidence angle; the material's absorptivity also increases. The TM mode exhibited the highest values at an angle of 60 degrees, while the TE mode displayed the highest values at an angle of 0 degrees. Tb-doped Mn-Ni-Cu ferrites are effective for electromagnetic interference (EMI), multilayer ceramic integrated circuits (MLCIs), shielding, and absorbing high-frequency signals in 5 G applications.

Charge storage mechanism and pseudocapacitance performance of NiO and Ce-doped NiO synthesized via modified combustion technique

Supercapacitors, as promising energy storage devices, have gained significant attention due to their ability to deliver high power and efficient charge storage mechanisms. In this work, we report the synthesis and electrochemical characterization of pristine NiO and Ni1-xCexO (x = 0.01, 0.02, 0.03) nanoparticles using a single-step auto ignition combustion method. Preliminary investigations indicate that Ni1-xCexO (x = 0.02) nanoparticles (2 % Ce doping) exhibit superior specific capacitance compared to other compositions. Therefore, we focused on structural, morphological, and vibrational studies on pristine and 2 % Ce-doped NiO. XPS and BET techniques were explored to assess the electronic state and porosity of the samples. Subsequent electrochemical performance evaluations included Cyclic Voltammetry (CV) at various scan rates, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopic (EIS) techniques. From CV at a scan rate of 5 mVs−1, specific capacitance values of 419 Fg-1 and 604 Fg-1 were obtained for pristine and 2 % Ce-doped NiO, respectively. GCD studies revealed a specific capacitance of 381 Fg-1 for 2 % Ce-doped NiO at a current density of 1 Ag-1 and demonstrated capacitance retention of 95.1 % over 3000 GCD cycles for a current density of 4 Ag-1. The symmetric two-electrode supercapacitor cell demonstrates exceptional electrochemical performance, exhibiting a high specific capacitance of 122 Fg-1, an impressive energy density of 8.17 WhKg−1, a power density of 700 WKg-1 at 1 Ag-1, and a remarkable 88 % capacitance retention after 5000 GCD cycles. DFT calculations suggest that Ce doping significantly alters pristine NiO's electronic and structural features due to lattice strain. Our work highlights the enhanced electrochemical performance of 2 % Ce-doped NiO and its potential as a good-quality supercapacitor material.

Tweaking the structural, micro–structural, optical and dielectric properties of anatase titanium dioxide via doping of nitrogen ions

The pure nanostructured anatase titanium dioxide (TiO2) and subsequent nitrogen–doped derivatives (TiO2–xNx; where, x = 0.005, 0.01, 0.05) were synthesized by sol–gel auto–combustion technique. XRD analysis confirms the formation of pure anatase phase of TiO2 up to doping of 1 mol% (x = 0.01) of nitrogen having tetragonal structure with space group of I41/amd whereas an additional monoclinic phase of TiO2–B was observed at 5 mol% of nitrogen doping in TiO2. This sample has smallest crystallite size of ∼4.7 ± 0.2 nm corresponding to TiO2–B phase and ∼12.0 ± 0.1 nm corresponding to anatase phase. XRD also reveals that the crystallite size of all other samples having pure anatase phase ranges between ∼8.7 ± 0.1 nm & 13.9 ± 0.1 nm. The crystalline phase revealed from XRD of all samples was further supported by the Raman analysis. The direct optical band gap of pure TiO2 (∼3.4 eV) was reduced non–monotonically after nitrogen doping in the ranges from ∼2.8 eV (TiO1.95N0.05) to ∼2.0 eV (TiO1.99N0.01). FTIR spectra confirm the metal oxide bond formation, surface adsorption of water molecules and presence of residual hydroxyl group in all crystalline samples. HRTEM analysis validates the coexistence of secondary phase of TiO2–B along with anatase phase of TiO2 in studied highest doped sample (TiO1.95N0.05) including its broader particle size distribution as compared to pure TiO2. The electrical studies reveal that the highest values of dielectric constant and ac conductivity can be realized for pure TiO2 and at 1 mol% (x = 0.01) of nitrogen doping, among all the studied nitrogen doped samples.

Influence of Nd3+ on structural, electrical and magnetic properties of Ni-Cd nanoferrites

Here in we report the nanocrystalline Ni1-xCdxNdyFe2-yO4 (0 ≤ x ≤ 1.0 in steps of 0.2: y = 0.0; 0.1) ferrites were synthesized by novel solution combustion technique. The sintered powders have been characterized by X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive analysis by x-rays (EDAX) methods. DC electrical conductivity carried out by two probe method. Magnetic parameters were measured using vibrating sample magnetometer with an applied magnetic field up to 15 kOe at 300K. The XRD results confirmed the formation of single phase cubic spinel structure formation. It was found that the lattice parameter increased with increase in Cd2+ ion. The crystallite sizes have been found in the range of 44.24 nm–15.467 nm. Moreover, the formation of two prominent absorption bands confirmed the spinel structure. The SEM micrographs evidenced almost spherical shaped, agglomerated and grainy structure of nanoferrites. Moreover, the Curie temperature (TC) was decreased with increasing temperature and exhibit the semiconducting behaviour. Further, saturation magnetization (MS), remanence magnetization (Mr); coercivity (HC) were decrease with increase in the magnetic field. The magnetic parameters; MS, Mr, nB increases attain maximum thereafter decreases with increase in Cd2+ ion and Nd3+ ion content.

The Determination of Woody Biomass Resources and Their Energy Potential from Hazelnut Tree Cultivation

The aim of this study was to estimate the shoot weight of four selected hazelnut cultivars and to see if the morphological characteristics of the cultivar and the age of the shoots affect their quality when used as fuel. This study shows that the cultivar ‘Olga’ generated the highest amounts of woody biomass (6507 t·ha−1), while ‘Olbrzymi z Halle’ generated the lowest (3843 t·ha−1). ‘Olbrzymi z Halle’ had the highest calorific values (HHVs) (18.08 MJ·t·ha−1 for annual shoots and 18.03 MJ·kg−1 for perennial shoots) and ‘Olga’ had the lowest calorific values (16.64 MJ·kg−1 for annual shoots and 16.39 MJ·kg−1 for perennial shoots). The age of the shoots had a minimal effect on the chemical and energy parameters. Emissions were the highest for ‘Olbrzymi z Halle’ (CO: 57.74 MJ·kg−1 for perennial shoots, CO2: 1414.05 MJ·kg−1) and lowest for ‘Olga’ (CO: 50.57 MJ·kg−1, CO2: 1238.46 MJ·kg−1). The cultivar ‘Olbrzymi z Halle’, which generated the least amount of biomass compared to the other cultivars, stands out for its high energy value due to its low moisture and ash contents and its high carbon and hydrogen contents, making it attractive for the purposes of biofuel production and supporting sustainable agriculture. The practical implications of the research findings include the selection of suitable varieties for biofuel production, the management of biomass moisture content, and the optimisation of combustion techniques to reduce emissions. The potential for using hazelnut shoots as a biofuel highlights the importance of sustainable agriculture and renewable energy production. The results provide valuable information that can support decisions regarding the cultivation and use of hazelnut shoots for biofuel production while minimising negative environmental impacts.

Enhancing the usability range of acetylene in CI engines through split injection of high-reactive fuel under RCCI operation: Optimized operability using an MCDM approach

Reactivity Controlled Compression Ignition (RCCI) has emerged as a promising solution to address the challenges of advanced combustion techniques in diesel engines, balancing combustion control and emission reduction. This study investigates the impact of split-injection high-reactivity fuel (HRF) dosing in RCCI to enhance charge homogeneity at lower injection timing advancements. It systematically explores progressive advancements in HRF injection timing, distinguishing between main and pilot injections. The main injection varied from 20° bTDC to 70° bTDC, while the pilot injection, relative to the main injection, spans 25°-40° CA ahead with a 5° progression. As an LRF, Port-injected Acetylene supplements the process with variable premixed ratios. Further, using a multi-criteria decision-making method (AHP), the study optimizes operating conditions, proposing a main injection at 20° bTDC, a pilot injection 40° CA ahead, and 70 % LRF participation. This optimized condition yields significant benefits such as 32.99 % higher brake thermal efficiency (BTE), 160 % longer premixed duration, 18.65 % lower maximum temperature, 89.41 % lower NO emissions, 91.83 % lower hydrocarbon (HC) emissions, 91.24 % lower CO emissions and 97.20 % lower smoke opacity compared to conventional diesel combustion (CDC) operation. The results highlight the advantages of multiple fuel injections in RCCI, improving blending characteristics at lower injection angles.

Adoptability assessment of HCDI and RCCI modes in plug-in parallel hybrid electric vehicles using sustainable fuels and model-based torque structure calibration strategies

In this research, a comparative analysis of plug-in hybrid electric vehicle (PHEV) engine was conducted with two advanced low temperature combustion (LTC) techniques viz. Homogeneous charge with direct injection (HCDI) and reactivity-controlled compression ignition (RCCI), utilizing alternative fuels diethyl ether (DEE) and ethanol. This was attempted to exhibit the promising potential of LTC based PHEV to achieve the highest efficiency and low emissions. The experimental results disclosed that DEE powered HCDI can achieve superior thermal efficiency with an impressive peak torque of 14 Nm. On the other hand, ethanol powered RCCI produced a peak torque of 17.5 Nm with remarkable emission reduction characteristics, especially CO2. It was vindicated that HCDI-PHEV outperformed the RCCI-PHEV in terms of fuel economy despite both HCDI and RCCI being lower than the conventional diesel PHEV. The NOx emissions from HCDI were almost negligible. About 20 % lower nitrogen oxide (NOx) emissions were recorded for RCCI respectively as compared to diesel (36 g/s). HCDI and RCCI showcased about 2 and 1.3 times higher soot emissions than diesel (7.12 g/s). Fuel economy was improved by 15 % and 43 % respectively under HCDI and RCCI modes over the conventional diesel mode of PHEV operation. When the PHEV was operated continuously for about 3.5 h, the battery's SOC dropped from 80 % to 45 % under diesel operation, whereas it only reached 50 % and 60 % under RCCI and HCDI mode operation. Low fuel consumption characteristics, acceptable torque production capabilities and ultralow NOx reduction potential established HCDI as the preferable choice for PHEV over RCCI.

Reaction mechanism of Ca(OH)2-based carbon storage suitable for the production of building materials

The development of CaCO3 oxyfuel combustion and calcium looping techniques offers opportunities for Ca(OH)2 production with near-zero CO2 emissions. This study investigated the viability of Ca(OH)2-based CO2 storage for use in the production of building materials. To resolve the deficient strength gain of Ca(OH)2 carbonation, siliceous materials, using fly ash as a model compound, were introduced into the raw mixture, and hydrothermal curing was applied to promote the pozzolanic reaction. Two microstructural features, i.e., inner and outer CaCO3 formations, were identified during Ca(OH)2 carbonation via backscattered electron imaging. Inner CaCO3 formation is characterized by Ca(OH)2–CaCO3 conversion within the edge of Ca(OH)2 particles. Outer CaCO3 formation is characterized by the dissolution of Ca(OH)2 and the precipitation of CaCO3 in capillary pores, which generates hollow microstructures. The hollow space can be further filled by Al-tobermorite during hydrothermal curing. The prepared materials are capable of storing up to 16 % CO2 by the mass of the raw mixture. Furthermore, the pore structure influenced by inner and outer CaCO3 formation demonstrates the feasibility of adjusting the material's mechanical and CO2 storing properties by controlling the carbonation and hydrothermal curing schemes.

Silver-Palm Kernel Expeller Ash Formation by Combustion Technique and its Congo-red Removal Activity

Silver-Palm Kernel Expeller Ash Formation by Combustion Technique and its Congo-red Removal Activity

Influence of carbon dots integrated in Pr3+ doped gahnite nanophosphor for thermal sensing, data fortification and fingerprint visualization analysis through YOLOv8x deep learning embedded model

The remarkable optical properties of carbon dots (CDs) render them highly promising as a versatile group of carbon-based nanomaterials. Integrating hydrothermally synthesized CDs into zinc aluminate doped with Pr3+ ions (ZnAl2O4:Pr3+) nanophosphors (ZAO:Pr3+ NPs) fabricated via the solution combustion (SC) technique holds great potential. The aim of synthesizing these nanocrystals (NCs) is to explore their potential uses in optical thermometry and anti-counterfeiting (AC) measures. The synthesized nanoparticles (NPs) and nanocomposites (NCs) underwent characterization using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra to verify their phase, morphology, particle size, oxidation state, and chemical composition. When excited at 447 nm, the Pr3+ doped ZAO: NPs exhibited an orange-red emission band at 614 nm. A remarkable enhancement in PL intensity, by a factor of 39.02 folds, is noted upon embedding CDs into the ZAO:Pr3+ NPs (CDs@ ZAO:Pr3+). The enhanced PL intensity can be ascribed to the Förster resonance energy transfer (FRET) mechanism. Even at a temperature of 423 K, the NPs retains 95.4% of its emission intensity compared to that at room temperature, showcasing exceptional thermal stability. The 5 wt% CDs@ZAO:1Pr3+ NCs demonstrate a high colour purity (CP) of 98.3%. Moreover, these NCs hold promise for optical thermometry applications across a broad temperature range spanning from 303 to 463 K. Utilizing the exceptional ZAO:1Pr3+ NPs and 5 wt% CDs@ZAO:1Pr3+ NCs, two representative white light emitting diodes (w-LEDs) have been successfully developed, boasting satisfactory luminous efficacy and colour-rendering index (CRI). This underscores their potential for high-performance w-LED applications. Simultaneously, a highly sensitive, non-contact optical thermometer has been engineered, featuring maximum relative sensitivities of approximately 44.51×10−4K−1 and 75.48×10−4K−1 at the emission intensities corresponding to 673, 693, 712 and 735 nm, respectively. We have developed a simple brush mode technique for creating a variety of patterns using the manufactured AC security ink. The latent fingerprints (LFPs) visualized using 5 wt% CDs@ZAO:1Pr3+ NCs exhibit excellent resolution and contrast, enabling the easy identification of fingerprint characteristics from levels I-III. Employing deep learning utilizing the YOLOv8x algorithm, fluorescence images of the revealed LFPs demonstrate remarkable alignment with standard controls, suggesting a high degree of similarity. In addition, the fabricated white light emitting diode (w-LED) boasts a favorable colour rendering index (Ra=87) alongside Commission International de L′Eclairage (CIE) coordinates (0.617, 0.376). Consequently, the inclusion of 5wt% CDs@ZAO:1Pr3+NPs showcases remarkable luminescent attributes and holds promising prospects across various applications.

Investigation of NO emissions and chemical reaction kinetics of ammonia/methane flames under dual-fuel co-combustion mode at elevated air temperature conditions

Utilising ammonia, which is one of the most promising carbon-free fuels, comes with the challenge of stable combustion due to its low reactivity. Therefore, advanced strategies are needed, including blending ammonia with highly reactive fuels or implementing innovative combustion techniques. For this reason, the present study proposes an ammonia-methane dual-fuel co-firing combustion mode. The second focus is to analyse the effect of preheating the main swirl air on NO emissions and examine the chemical kinetic reactions. Experimentally, chemiluminescence imaging was conducted to analyse OH* and NH2* emissions to evaluate the flame structure and reaction zones. Numerically, simulations were performed using a chemical multi-reactor network model to examine kinetics. By comparing the fully premixed combustion to the dual-flame co-burning mode, the NO emissions decreased by 80% in the latter case at T = 473K and ϕ = 0.6. The NH3 reaction pathway analysis shows a significantly higher percentage reduction of NO and NH2 reactions in dual flame mode compared to premixed flames. Preheating the main air impacts NO reactions in the dual flame mode, allowing for lower NO emissions.

Response surface methodology based investigations of total organic carbon removal using cerium oxide nanoparticle

This study aimed to optimize the removal of total organic carbon (TOC) from drinking water using cerium oxide nanoparticle (CONP) through response surface methodology (RSM) based approach. The CONP was synthesized using an efficient microwave combustion (EMC) technique. It was further characterised by High-resolution transmission electron microscopy (HR-TEM), X-Ray diffraction (XRD), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, and zeta potential. CONP was found highly efficient in removing up to 94 % TOC at the optimum condition i.e., pH = 7, dosage = 0.5 g/L, and contact time = 30 min. Pareto analysis revealed that amongst all the selected variables, the CONP dose had the greatest cumulative impact on TOC removal. The second-order polynomial model developed using the RSM technique was found highly accurate in predicting the removal of TOC from drinking water (R2 = 0.98). The study offers a unique approach for reducing the number of experimental trials and arriving at an optimal experimental conditions to achieve higher TOC adsorption efficiency.

Exploring γ and UV irradiation responses on thermoluminescence and optical thermometry studies on Y4Al2O9:Ho3+ nanophosphor

A series of green emitting Ho3+ (1–9 mol%) doped Y4Al2O9 nanophosphors (NPs) are synthesized via solution combustion technique. Photoluminescence (PL) studies shows emission peaks recorded at ∼ 522 nm (5F3→5I8), 545 (5F4, 5S2→5I8), 659 (5F5→5I8) and 730 (5F4→5I7) upon excited at 460 nm wavelength. With a tremendous potential for application in white light-emitting diodes (w-LEDs), the phosphors show a bright green emission under 460 nm excitation. They also have a notable activation energy (0.31 eV), high color purity (98.2 %), and a remarkable quantum yield (87.1 %). Most astonishingly, even at temperatures as high as 420 K, YAO:5Ho3+nanoparticles retain 88.9 % of their initial fluorescence intensity. Using the fluorescence intensity ratio (FIR) method, the temperature sensing potential is also investigated. Thermoluminescence (TL) glow curves of γ (1 kGy) and UV (1 h) irradiated YAO:Ho3+(1–9 mol%) NPs exhibit two glow curves and highest intensity is recorded for YAO:5Ho3+NPs. TL characteristics of 5 mol% Ho3+ doped YAO NPs are subjected to γ (1 Gy-5 kGy) and UV (0.25–6 h) irradiation. Two glow curves recorded at 475 K (major peak) and 567 K (shouldered peak) for γ irradiation. However, for UV irradiation two glow curves at 478 K (major peak) and 575 K (shouldered peak) are recorded utilizing a 5 °C per minute heating rate. TL intensity varies with γ and UV exposure is recorded for optimized NPs and major glow peaks showcase linear response for both γ and UV irradiations, indicating that the prepared phosphor can be used in TL personal dosimetry. Furthermore, compared to γ-irradiated phosphor, UV-irradiated phosphor shows greater fading. The overall results clearly demonstrate that the optimized phosphor has proven to be an outstanding candidate for multifunctional applications.

Optimizing oxygen transport properties in Al-substituted La0.5Sr0.5Co0.8Fe0.2-xAlxO3-δ (x = 0–0.20) perovskites

In recent years, there has been a surge in the investigation of perovskite-type complex oxides, with a particular focus on La1-xSrxCo1-yFeyO3, renowned for their exceptional mixed ionic-electronic conducting (MIEC) properties. La0.6Sr0.4Co1-yFeyO3 compositions have prominently emerged in this research domain. The hypothesis of enhancing redox stability and mitigating oxygen variations by incorporating trivalent aluminum (Al3+) into the B-site of perovskite structures has gained attention. In this study, single-phase La0.5Sr0.5Co0.8Fe0.2-xAlxO3-δ (x = 0–0.20) perovskite oxides were synthesized using the solution combustion technique. The physicochemical properties of the synthesized materials were thoroughly characterized, including their morphology, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) analysis, oxygen nonstoichiometry, and electrical transport properties. Results revealed lattice parameter variations associated with oxygen nonstoichiometry and B-site cation size, exhibiting a decline up to x = 0.10 followed by an increase. Al-substitution significantly influenced surface morphology, oxygen nonstoichiometry, and electrical conductivity. Notably, La0.5Sr0.5Co0.8Fe0.1Al0.1O3-δ displayed lower electrical conductivity (676 S cm−1 at 300 °C) among the studied oxides. Oxygen nonstoichiometry had a significant impact on oxygen transport parameters, with these perovskites demonstrating improved chemical diffusion coefficient, Dchem (5.5 × 10-5 cm2 s−1), and the oxygen surface exchange coefficient, Kchem (2.32 × 10-5 cm s−1) at 900 °C, suggesting its potential as an oxygen transport membrane. These findings underscore the promising role of Al-substituted perovskite oxides in various advanced applications.

Substitutional effects of the anionic group systems [BO33−], [PO43− ], and [SO42−] on the down-conversion photoluminescence properties of Y2O3:Er3+ nanophosphors

A series of Y2O3, Y2O3: Er3+ (1 %) and Y2O3-AG: Er3+ (1 %) (where AG = BO33−, PO43−, and SO42−) nanophosphors were prepared via a chemical combustion technique. The primary X-ray powder diffraction results showed that the Y2O3:Er3+ phosphor materials crystallized into a cubic standard structure, while the Y2O3-AG: Er3+ phosphor materials transformed to hexagonal and tetragonal structures for the [PO43−] and [BO33−]-based phosphors, respectively. However, no changes were observed for the [SO42−]-based phosphor materials. The scanning electron microscope micrographs revealed that the particles were formed in the nanometre range with different sizes and shapes. The fourier-transformed infrared spectra showed the presence of various structural groups in the pure Y2O3 and Y2O3-AG: Er3+ phosphors. In addition to that, the optical bandgap energy values were obtained using the diffuse reflection spectra (DRS) spectra and Kubelka-Munk function theory. Under UV-379 nm excitation for the Y2O3-AG: Er3+ phosphors, the Y2O3–SO4: Er3+ emitted the most intense green light at 563 nm wavelength. The Commission Internationale de l'Elcairage colour coordinates and correlated color temperature values indicated that the Y2O3:Er3+, Y2O3-PO4:Er3+, and Y2O3–SO4:Er3+ phosphor materials are potential candidates for producing enhanced green color components in white light-emitting diode (w-LED) applications.

Fabrication and magnetic performance of rare-earth dysprosium doped Ca-Mg hexaferrite nanoparticles

In this research, dysprosium-substituted M-type Ca-Mg hexaferrites are successfully fabricated via sol–gel combustion technique, employing a nominal composition of Ca0.5Mg0.5Fe12-xDyxO19 (x = 0.0, 0.04, 0.08, 0.12, and 0.15). Analysis of XRD patterns reveals exclusive peaks corresponding to the M-type hexaferrite, with no indications of additional phases, underscoring the high purity and crystalline integrity of the synthesized material. The Rietveld refinement is used to evaluate lattice parameters ’a’ and ’c’ along with the cell volume ’V ’ using the distinct iron sites. Notably, a discernible upward trend in both lattice constants and cell volume emerged with the gradual introduction of dysprosium Dy+3 ion. Hexaferrite phase formation was also confirmed through the ‘c/a’ ratio which lies below the critical value of 3.98. Synthesized samples shows a composite surface morphology with adherent clusters of small crystals and well-formed individual crystals. VSM analysis suggests, remarkable results, particularly at the x = 0.15 doping level, which exhibits the highest magnetic parameters, including Ms = 32.13 emu g−1, Mr = 20.34 emu g−1, and Hc = 1.418 kOe. These results suggest that the synthesized samples hold promise as suitable contenders for optimizing recording media, offering the potential for improved data storage performance.