Sol Gel Auto-combustion Process Research Articles

Effects of La3+ doping on the structural, vibrational, elemental, and dielectric characteristics of Sr-Ba-Zr2 R-type hexaferrite

Hexagonal ferrites possess physicochemical and dielectric features that make them highly favorable for absorption purposes. Due to its excellent characteristics at high frequencies, R-type hexagonal ferrite is specifically designed for efficient microwave absorption. Samples of R-type hexaferrite were prepared using the sol-gel auto-combustion process. The samples had the chemical composition Sr0.7Ba0.3Zr2Fe4-xLaxO11, where x ranged from 0.00 to 0.09 in increments of 0.03. This replacement seeks to enhance the understanding of how the La3+ ions affect the physicochemical characteristics of these ferrites, such as their structure, dielectric properties, XPS, and FTIR properties. The single phase of R-type hexaferrite is confirmed by the FTIR and XRD methods. The crystallite size of the samples of R-type hexaferrite doped with La was determined using three different methods. The crystallite size, determined using Sherrer's formula, ranged from 25.865 to 41.393 nm. Meanwhile, the size calculated using Williamson's method was between 36.084 nm and 62.32 nm. The Size-strain analysis revealed a size range of 24.26 nm to 27.31 nm. The FTIR spectra exhibit two intrinsic vibrational bands, labelled as υ1 and υ2, in the wavenumber range of 400 to 600 cm-1. The XPS examination verifies the elemental composition of a representative specimen that has been swapped with La. As the La3+ content increases, additional semicircles are formed, suggesting the existence of more mechanisms for polarization relaxation and a greater capacity for polarization loss. Out of all the compositions that were created, the material with a composition of x = 0.09 exhibits the highest absorption capabilities. This is because of its minimal reflection loss. By replacing the La3+ element in R-type hexaferrites, the peak of the sample moves towards the higher frequency range, indicating excellent microwave absorption properties. R-type hexaferrites are utilized in transformers to reduce eddy current losses and in microwave absorption devices.

Green mediated sol-gel synthesis of MxCu1-xO (M = La,Ce x = 0.02–0.06) as an efficient catalyst for electrocatalytic oxygen evolution reaction

The imperative for advancing contemporary human society lies in the essential requirement to create energy generation systems that are sustainable, environmentally friendly, and exceptionally efficient. The development of efficient electrocatalysts, that are environmentally benign, economically viable and easily available, for alkaline oxygen evolution reaction is a significant research area in this regard. The present study focuses on a green mediated sol–gel auto-combustion process for the synthesis of lanthanum and cerium doped copper oxide nanoparticles with excellent electrocatalytic activity. Citric acid and polyols enriched lemon juice serves as the medium for the synthesis of various metal doped copper oxide nanoparticles. The extensive electrochemical studies using these catalysts reveals that, among the various doped samples, 5% lanthanum and 5% cerium doped catalysts exhibited the best performance in oxygen evolution reaction. Doping was found to enhance electrical conductivity and create oxygen vacancies, which enhanced the electrocatalytic activity of the catalysts. Specifically, the 5% lanthanum-doped copper oxide showed an overpotential of 340 mV, while the cerium-doped material exhibited an overpotential of 337 mV at a current density of 10 mA cm−2 in 1 M KOH. Moreover, the lanthanum-doped sample displayed a Tafel slope of 49 mV dec−1, whereas the cerium-doped sample had a Tafel slope of 60 mV dec−1 with better durability. Additionally, the chronopotentiometric studies revels the stability and long-term performance of LCO5 and CCO5, maintaining consistent potential of 1.58 V throughout 5 h at a current density of 10 mA cm−2. This study is conclusive evidence that the incorporation of rare earth elements improves the conductivity and overpotential of pristine copper oxide nanoparticles, making them highly effective in the oxygen evolution reactions.

Photocatalytic degradation of rhodamine B using Yb3+-Doped Zn-Mg ferrites synthesized via conventional sol-gel auto-combustion method

The primary goal of our research is to develop a photocatalyst capable of degrading organic molecules in water, achieved through the rare earth Yb3+ doping of Zn-Mg spinel ferrites. A key element of our approach is the use of the conventional sol-gel auto-combustion process, which has proven to be an effective method for synthesizing a high-performing, visible light-driven Zn0.9Mg0.1Fe2-xYbxO4 (x = 0.000, 0.015, 0.030, 0.045, 0.060 and 0.075) nano-ferrites. Many analytical techniques were employed to evaluate the material's physicochemical characteristics, including P-XRD, EDX, FE-SEM, HR-TEM, FTIR, UV–vis, BET, VSM, EIS, and photocatalysis was carried out against the RhB. The impact of Yb3+ ion doping on the material's crystallite size and lattice parameter has been evaluated. It was found that all the samples' crystallite sizes increased between 33 and 41 nm. These magnetite nanoparticles have spherical forms and nanometric particle sizes, as revealed through field scanning electron microscopy (FE-SEM). The FTIR spectra bands at ʋ1 (518–535) and (401–411) ʋ2 subsequently revealed the spinel structure of the synthesized nano-ferrites. The band gap in zinc manganese ferrite increases from 2.51 eV to 2.92 eV after adding ytterbium. The surface area of the Yb3+-doped Zn-Mg ferries ranges from 23.6 m2/g to 27.8 m2/g, making them an excellent choice for data storage. The investigation of magnetic behavior shows the superparamagnetic behavior of all the samples. The produced sample's determined squareness value indicates the magnetostatic interaction between the particles. Because of the low produced coercive field value, these materials can be used in ferrofluids and hyperthermia therapy applications. Furthermore, with a higher RhB removal of 93.80 %, the Yb3+-doped sample photocatalyst successfully separated carriers generated by sunlight. The Yb3+-doped sample (ZMY-5) photocatalyst showed outstanding stability after one cycle of the stability test, obtaining an outstanding RhB elimination of 93.80 %. Zn0.9Mg0.1Yb0.075Fe1.925O4 photocatalyst has substantial promise for large-scale pollutant treatment due to its simple synthesis method, superior magnetic characteristics, exceptional photocatalytic activity for RhB, and excellent stability.

Exploring the multifaceted properties of zinc-doped nanocrystalline calcium chromite: A comprehensive investigation into structural, morphological, optical, and magnetic behavior

The production of CaCr1−xZnxO3 a calcium chromite doped with zinc (0 ≤ x ≤ 0.4). The samples were prepared using the sol-gel auto-combustion process, and then we analysed their optical and dielectric characteristics, microstructure, and morphology to determine how doping with Zn affected them. The microstructural investigation verified that the samples were composed of a single phase through the use of X-ray diffraction and Fourier transform infrared spectroscopy. The crystallite size was determined using the Scherrer equation and Williamson-Hall analysis, while the lattice parameters, density, unit cell volume, bond lengths, and bond angles were all clarified from Xrd data. Both the size of crystallites and the volume of unit cells increased as the Zn level grew. The creation of uniform and regular samples was confirmed by surface morphology examination using SEM-EDX. Furthermore, optical properties revealed a decrease in the optical energy bandgap (Eg) and an increase in Urbach energy with rising Zn doping. Magnetic saturation exhibited an initial increase from x = 0.1 to 0.4 (35.4–55.7 emu/g) followed by a decrease from x = 0.3 to 0.4 (41.6–40.7 emu/g) as Zn progressively occupied A and B sites. VSM results also indicated a decrease in remanence (Mr) and coercivity (Hc) with increasing Zn concentration.

Multi-metal ferrite as a promising catalyst for oxygen reduction reaction in microbial fuel cell.

Improving catalytic activity of cathode with noble metal-free catalysts can significantly establish microbial fuel cells (MFCs) as a sustainable and economically affordable technology. This investigation aimed to assess the viability of utilizing tri-metal ferrite (Co0.5Cu0.5 Bi0.1Fe1.9O4) as an oxygen reduction reaction (ORR) catalyst to enhance the performance of cathode in MFCs. Trimetallic ferrite was synthesized using a sol-gel auto-combustion process. Electrochemical evaluations were conducted to assess the efficacy of as-synthesized composite as an ORR catalyst, employing electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). This evaluation revealed that the impregnation of bismuth in the Co-Cu-ferrite structure improves the reduction current response and reduces the charge transfer resistance. Further experiments were conducted to test the performance of this catalyst in an MFC. The MFC with tri-metal ferrite catalyst generated a power density of 11.44 W/m3 with 21.4% coulombic efficiency (CE), which was found to be comparable with commercially available 10% Pt/C used as cathode catalyst in MFC (power density of 12.14 W/m3 and CE of 23.1%) and substantially greater than MFC having bare carbon felt cathode without any catalyst (power density of 2.49 W/m3 and CE of 7.39%). This exceptionally inexpensive ORR catalyst has adequate merit to replace commercial costlier platinum-based cathode catalysts for upscaling MFCs.

Er3+ ion-doped Mg-Zn nanoferrite: Properties and applications in dielectric, magnetic, structural, and optical domains affected by calcination temperature

A series of Mg-Zn ferrites with Er3+ion doping in the shape of cubic spinel were produced using the citrate sol–gel auto-combustion process known as Mg0.5Zn0.5Er0.1Fe1.9O4 (MZE) (calculated at 400, 550, 700, 850, and 1000 °C), and the same was confirmed with the XRD diffractograms. It was possible to understand the presence of hydrated water, which degrades behavior. Hence, the powders created were sintered at various temperatures for four hours. After that, it was observed that the cubic spinel phase was free of impurities. The as-prepared spinel Mg-Zn ferrite nanoparticles also showed a specified behaviour, according to the results. The SEM, UV–Vis spectroscopy, FT-IR (Fourier transform infrared) spectroscopy, TG-DTA (thermogravimetric and differential thermal analysis), XRD (X-ray diffractometer), LCR metre, and VSM (vibrating sample magnetometer) were the characterization techniques used to examine the samples' structural, optical, dielectric, and magnetic properties. A microstructure investigation was done using FESEM analysis. Based on these FESEM measurements, the nanoparticles' sphere-shaped structure was confirmed. FT-IR spectroscopy has been employed to examine the chemical bonds in the spinel ferrite. There is evidence of a shift in bands ν1 and ν2. The produced materials' semiconducting qualities are demonstrated by the optical band gap energy, which is in the range of 1.648–1.798 eV. Variation of dielectric parameters with Er doping was measured in the frequency range from 100 Hz to 1 MHz at room temperature (RT) and at temperatures of 100–400 °C. These results were very well supported by Maxwell-Wagner interfacial polarization. The dielectric properties were observed to decrease with an increase in frequency due to calcinated MZE samples. The magnetic properties of ferrite nanoparticles were investigated in detail at 300 K and 5 K. Early signs of superparamagnetic behaviour have been observed in the prepared sample. It is used in industries like nanoelectronic devices, detectors, imaging devices, super-paramagnetic coils, and magnets.

Synthesis and Characterization of (Ni,Co)xMn0.25-xMg0.75Fe2O4 Nanoparticles

Ni-Co-Mn-Mg ferrite nanoparticles with the formula (Ni,Co)xMn0.25-xMg0.75Fe2O4 were synthesized in this work by employing the sol-gel auto-combustion process, with nitrates used as the cations source and citric acid (C6H8O7) as the combustion agent. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and a vibrating sample magnetometer (VSM) were used to characterize the structural, morphological, and magnetic properties of ferrite powders. The XRD measurements showed crystallite sizes ranging between 24 - 28 nm. The FE-SEM images show the presence of agglomeration as well as a non-homogeneous distribution of the samples. On the other hand, the stoichiometry of the reactant solutions that were used is in close agreement with the elemental analysis that was obtained from EDX showing that the composition was as expected. Manganese ferrite showed a decrease in magnetic parameters on magnesium doping, which was further enhanced in (Ni,Co)xMn0.25-xMg0.75Fe2O4 nanoparticles upon replacement of nonmagnetic manganese ions for nickel and cobalt ions. Results indicated that Ni-Co-Mn-Mg ferrite nanoparticles’ crystal morphology, structural, and magnetic properties were significantly influenced by the amounts of nickel and cobalt content.

Nano MgCuAl2O5: Synthesis by Sol-Gel Auto-Combustion Process, Characterization and Reusable Heterogeneous Catalyst for the Hantzsch 1,4-Dihydropyridine Reaction

For the first time, MgCuAl2O5 heterogeneous nanocatalysts were prepared by sol-gel auto-combustion method, which displayed great yield and suitable activity for the preparation of 1,4-DHP derivatives with high efficiency in green solvent ethanol/water (1:1) at 80 °C under one pot condition. The synthesis materials were separated in short reaction times with excellent yield (80–95) %. Moreover, the synthesized nanocatalyst was easily retrieved and continuously reused for six reactions without a noticeable significant loss of proficiency. The solid catalyst was confirmed by XRD, BET, FTIR, FESEM and EDX, and the substituted 1,4-dihydropyridines were characterized by melting point, 1H and 13C NMR.

Physical characterization, magnetic interactions and DC electrical resistivity properties of La3+ substituted NiZnCd nano ferrites

In this article, we substituted La3+ ions to explore the structural, magnetic, and DC electrical resistivity properties of Ni0.5Zn0.4Cd0.1Fe2-xLaxO4 (x = 0.0, 0.02, 0.04, 0.06, and 0.08) nano-structured spinel ferrites. We employed X-ray diffraction (XRD), Field-emission scanning electron microscopy (FESEM) with Energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), Vibrating sample magnetometry (VSM), and electrical measurements to characterize the studied samples, which were synthesized using the sol–gel auto-combustion process. XRD analysis confirmed that the prepared materials formed a single-phase nanostructure. Using Debye-Scherer's formula, we calculated the average crystallite size, which ranged from 29.01 to 21.52 nm. FESEM images demonstrated that each sample exhibited spherical nanocrystalline behavior. The variations of the prepared samples were confirmed constitutionally by EDX. The FTIR data revealed two absorption bands for all synthesized materials at υ1 = 562.18 to 590.51 cm−1 and υ2 = 410.18 to 430.51 cm−1, corresponding to the tetrahedral and octahedral sites of the spinel structure, respectively. Vibrant sample magnetometry spectra were utilized to investigate how La3+-doping affects the magnetic characteristics of NiZnCd ferrite. Due to enhanced La3+-doping, saturation magnetization, and coercivity values decreased. The La3+ doping of NiZnCd nano ferrites resulted in changes in saturation magnetization (from 83.66 to 69.57 emu/g), coercivity (from 33.75 to 60.51 Oe), and remanence magnetization (from 29.62 to 33.12 emu/g). These variations suggest the potential utility of the samples for magnetic recording and memory applications. The semiconducting behavior has been confirmed by the DC electrical resistivity measured values using a two-probe method. Data on DC electrical resistivity were also utilized to determine carrier concentration and activation energy, establishing a connection with La3+ replacement.

Effect of Calcination Temperature and Substitution of Erbium on Structural and Optical Properties of Nickel Zinc Ferrite Nanoparticles

A single composition of erbium-doped nickel zinc ferrite Ni0.5Zn0.5Fe1.95Er0.05O4 is synthesized by the sol-gel autocombustion process. The prepared composition was divided into five equal parts. One of the parts was an as-prepared sample, and remaining four other parts were calcinated at 600, 700, 800, and 900 ∘C to investigate the variation in structural and optical properties with the calcination temperature. The structural characterization was performed using XRD and SEM. Optical properties were analyzed using FTIR and UV-Visible spectral data. XRD patterns confirm the spinel cubic crystal structure and the Fd3m space group. The crystallite size was minimum for the as-prepared sample (17.9452 nm), and the crystallite size was maximum for the sample calcinated at 900 ∘C (29.8481 nm). SEM images revealed the grain size in the interval from 55.38 nm to 177.73 nm, and certain nanotubes were formed in the sample calcinated at 800 ∘C. Optical energy band gap was observed in the interval from 5.556 eV to 3.969 eV. All these testifies to the variations in structural and optical properties of Ni0.5Zn0.5Fe1.95Er0.05O4 with the calcination temperature.

Structural and magnetic properties of SmCo/Co nanocomposites elaborated using sol–gel auto-combustion strategy

Sm–Co nanomagnetic material has received much attention recently since it is thought to be the next generation of permanent magnets with potential uses in energy technologies. Here, ethylenediaminetetraacetic acid (EDTA) is utilized for the first time as a fuel source in a sol–gel auto-combustion process to synthesize Sm–Co nanoparticles. Then, reduction–diffusion process strategy followed the auto-combustion pathway. Typically, Sm2O3 and Co3O4 nanoparticles were prepared by combining Sm and Co nitrates with the chelating agent EDTA. The Sm–Co nanocomposites were subsequently created by reductively annealing precursor oxides using calcium powder. To display the temperature-dependent breakdown of the original precursor and determine the correct annealing temperature, TGA was employed to identify the annealing temperature and the precursor products. Additionally, other physical characterization techniques such as XRD, FE-SEM, EDX, and VSM were used for further investigations. Three distinct Sm1Cox compositions with different cobalt ratios (x = 4.0, 3.5, and 2.0) were prepared and studied. The findings demonstrate that the composition Sm1Cox (x = 2.0) led to the formation of hard phases of SmCo5, Sm2Co7, and Sm2Co17. These particles’ morphology reveals that they are made up of nanowires with an average thickness of 25 nm. As well, according to the VSM findings, this composite had the highest coercivity Hc and a maximum squareness ratio Mr/Ms, which were 2161 Oe and 0.57, respectively.

High-temperature variable range hopping conduction and dielectric relaxation in CoFe2O4 ceramic

CoFe2O4 ceramic was fabricated using a sol-gel auto-combustion process. The cubic spinel structure with F d −3 m space group symmetry was confirmed through the Rietveld refinement of the XRD pattern of CoFe2O4 sintered at 800 °C for 4 h. The cobalt vacancies at the tetrahedral site were verified by electron density distribution calculated through the maximum entropy method. The impedance spectroscopy study revealed that the grain boundary was dominant compared to the grain in the electrical properties of CoFe2O4. The total dc resistivity was fitted by the variable range hopping (VRH) model, demonstrating that the charge carriers for conduction mechanism confirm to the VRH model. The density of localized states (N(EF)) near the Fermi level was found to be 1.07 × 1019 eV−1-cm−3. The hopping energy (EH) and hopping length (R) of the charge carriers were estimated to be 0.29 eV and 2.28 nm, respectively, at 473 K.

Electrically and magneto-dielectrically modified La3+ doped Co0.3Li0.1Ca0.5Fe2.1-xLaxO4 spinel ferrites and their potential applications

Low temperature and more efficient sol-gel auto combustion process was utilized to synthesize Co0.3Li0.1Ca0.5Fe2.1-xLaxO4 [La-CLCF] spinel ferrites (where x = 0.00, 0.01, 0.02, 0.03, 0.04, and,0.05). The La-CLCF sample's structural, optoelectrical, dielectric, and magnetic properties were examined as a result of La3+ doping. All synthesized La-CLCF samples have single-phased spinel matrix, according to X-ray diffraction (XRD) analysis. It was found that the crystallite size was 11 nm, and the bandgap energy of 3.45 eV for La3+ doping x = 0.03. The resistivity and activation energy both were increased with the substitution of La3+ in the CLCF spinel matrix, while the peak position of temperature coefficient of resistance (TCR) percentage was − 3.92%/K at 372 K for sample x = 0.03. The alternating current conductivity improves with frequency, whereas the dielectric constant and tangent loss decrease as frequency increases. Further, the saturation magnetization and the microwave operating frequency for all the samples were reduced with the doping of La3+. The minimum coercivity was 242 Oe at x = 0.03. Our study suggested that the Co0.3Li0.1Ca0.5Fe2.07La0.03O4 sample is tested as an active material for potential use in high-frequency applications, electromagnetic wave absorbing material, and evaluating the sensitivity of infrared (IR) detectors used in night vision bolometers.

Optical, magnetic, and electrochemical properties of a fluorite-perovskite Ce0.9Gd0.1O2-∂ - La0.6Sr0.4FeO3-∂ nanocomposite synthesized by one pot sol-gel auto-combustion route

Gadolinium-doped cerium oxide (Ce0.9Gd0.1O2-∂; CGO) and strontium-doped lanthanum ferrite (La0.6Sr0.4FeO3; LSF) are well-known compounds for their application in solid oxide fuel cells, dense oxygen permeable membrane, and high-temperature ceramic reactor. The superior electro-catalytic performance of these two individual oxides or their composites is well established as it originates from multivalent cations (Ce3+/4+ and Fe2+/3+/4+) and doping-induced defects like electrons, holes, and oxygen vacancies. This work focuses on synthesizing and characterizing composite taking CGO and LSF in different weight ratios, i.e., 10:90, 30:70, 50:50, 70:30, and 90:10 by sol-gel auto-combustion process. End members CGO and LSF were also synthesized for comparison purposes. All synthesized nanopowders (single phases and their composites) were characterized with X-ray diffraction (XRD) for phase identification and Scanning electron microscopy (SEM) for elemental composition analysis. XRD and SEM results established the formation of the required phase and targeted composition. The optical properties of the materials were evaluated with the help of ultraviolet–visible Diffuse Reflectance Spectroscopy (UV–Vis DRS). Tauc's approximation measured band gap energies, and all the composites showed a very high band gap in the 4.85–5 eV range. Magnetic properties such as saturation magnetization (Ms), remanence (Mr), and coercive force (Hc) were calculated from a magnetic hysteresis loop obtained from the Vibrating-sample magnetometer (VSM) experiment at room temperature. Furthermore, the law of approach to saturation (LAS) model was applied to more precisely calculate Ms and other essential parameters. In magnetic characterization, the LSF phase fraction controls the overall magnetic property of the composites. Electrochemical behavior, such as the composites' charge storage ability and stability were tested by cyclic voltammetry and chronopotentiometry method. All the samples exhibited good stability, and the highest specific capacitance of 26 F/gm was obtained for the composite sample (CL91) when only 10 % LSF phase was incorporated in the nanocomposite.

Structural, optical, electrical and magnetic properties of aluminum substituted Co–Cu–Zn nano-crystalline ferrites

Strong electrical resistivity, low eddy current and dielectric losses, high saturation magnetization, high permeability, and other significant electrical and magnetic properties of nano-ferrites are only a few. In this investigation a sincere effort has been tried to manufacture Co0.7Cu0.2Zn0.1Fe2-xAlxO4 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) nano-ferrites utilizing sol-gel auto-combustion process and systematically characterize the structural, optical, electrical and magnetic features. All the peaks belonging to XRD confirmed a structure of the spinel class and single phase with zero impurities. The intensity ratios are generated for a number of cation combinations occupying tetrahedral and octahedral B site. The higher band (ν1) is identified in between wave numbers 550-600 cm−1 as a result of the vibrations of stretching pertaining to the metal-oxygen tetrahedral band. The grain sizes are measured by the use of image J software associated with the SEM, which are indicated on the images in the range of 3.14 μm–1.215 μm. With a frequency-independent characteristic, the dielectric loss dwindles quickly at low frequencies and slows down at high frequencies. Because of spin non-collinearity at the crystal's surface, the saturation magnetization values climb as particle sizes increase. The coercivity values gradually decline as aluminum concentration rises.

Gd2ZnMnO6/ZnO Ceramic Nanocomposites for the Cycloaddition of Carbon Dioxide, Amines, and Alkenes under Mild Conditions

For the first time, Gd2ZnMnO6/ZnO ceramic nanocomposites (Gd2ZnMnO6/ZnO CNCs) were fabricated by a sol-gel auto-combustion process on the basis of a reaction between Gd, Zn and Mn nitrates and saffron as a green fuel. Gd2ZnMnO6/ZnO ceramic nanocomposites were greenly formed using saffron as a novel fuel and stabilizing agent. The morphology, phase, and anatomical purity of Gd2ZnMnO6/ZnO ceramic nanocomposites could be arranged by quantity and type of fuel, temperature, and reaction period. The specimens were explored by various microscopic and spectroscopic approaches. The uncontrolled release of carbon dioxide (CO2) by industrial processes that acidify the oceans and warm the planet has prompted scientists to try different methods to capture CO2 directly from waste water sources. The fabrication of green nanocatalysts with chemical modifications to create value-added products has many benefits. Considering the morphology of Gd2ZnMnO6/ZnO, an appropriate exteriorlayer for CO2 imbibition was created in all catalystsites. Findings disclosed that Gd2ZnMnO6/ZnO positively affected the fabrication yield of 3-aryl-2-oxazolidinones by carbon dioxide, olefins, and anilines. The product was obtained with an excellent yield of 98%. This high yield was obtained in very mild conditions, such as a pressure of 2.5 atm of carbon dioxide at 80 °C for 3 h. The technique enjoyed profitable performance and forbearance of functional groups. The retrievable catalyst was recycled up to ten times for synthesis of 3-aryl-2-oxazolidinones without significant loss in its activity.

Superior energy storage performance and excellent multiferroic properties of BaTi1-xGdxO3 (0 ≤ x ≤ 0.06) ceramics

Ceramic based capacitors with superior energy storage performance and high storage energy density play an important role in modern electronic devices. Several ferroelectric materials with high dielectric constant and relaxor behavior become the most promising systems for realizing higher energy storage performance. In the present work, environmentally lead-free BaTi1-xGdxO3 (0 ≤ x ≤ 0.06) nanostructures were synthesized using the sol-gel auto-combustion process. The doping of Gd at the Ti site causes the transformation of the ferroelectric behavior to the relaxor ceramics, which is important for finding the large energy storage efficiency of the material. The surface morphology of undoped and doped samples was examined through the SEM studies. Ferroelectric study evidence that the system is going to a more symmetric phase due to a reduction in the polarization parameters and enhancement in the leakage current density. Moreover, the energy discharge density and energy storage efficiency were boosted in x = 0.02 and x = 0.04 samples with energy storage efficiencies reaching ∼81% and 83%, respectively. The linear enhancement in the magnetic moment and the dielectric constant in the doped sample make the system favorable for multifunctional applications. The samples' piezoelectric constant (d33) remains preserved under Gd doping. Hence, the present study opens a propagable and feasible route to synthesize novel lead-free ferroelectric material for energy storage applications.

Phosphorus-modified copper ferrite (P–CuFe2O4) nanoparticles for photocatalytic ozonation of lomefloxacin

Phosphorus-modified copper ferrite (P–CuFe2O4) nanoparticles were prepared by a simple sol-gel auto-combustion process and used for the photocatalytic ozonation of lomefloxacin (LOM). The morphology, crystallinity, and structure of the synthesized CuFe2O4 and P–CuFe2O4 nanoparticles were investigated using various techniques. The high-performance liquid chromatography (HPLC) analysis revealed that the degradation of LOM achieved a 99% reduction after a duration of 90 min in the photocatalytic ozonation system. In accordance with the charge-to-mass ratio, four intermediates were proposed with the help of their fragments obtained in LC–MS/MS. The degradation kinetics of lomefloxacin followed a pseudo-first order reaction, and the degradation mechanism was proposed based on the results. P0.035Cu0.965Fe2O4 showed the highest total organic carbon (TOC) removal with 20.15% in 90 min, highest specific surface area and the highest fluoride and ammonium production using the ion chromatography (IC). The experimental results obtained from the electron paramagnetic resonance (EPR) analysis indicated that the modified P–CuFe2O4 samples exhibited significantly elevated levels of superoxide (.O2−) production compared to the CuFe2O4 samples. The findings of this study demonstrate that the introduction of phosphorus modification into the copper ferrite photocatalyst led to an augmentation of both the specific surface area and the total pore volume. Furthermore, the incorporation of phosphorus served to promote the efficient separation of electron-hole pairs by effectively trapping electrons in the conduction band, hence enhancing the degradation efficiency.

Optimization of dielectric phenomenon in 0.8[(1-x)SrCoO2.29 + xCr2FeO4] + 0.2PZT tri-phase composites

Composite materials are emerging and have potential to revolutionize the modern technology. In this work, a series of tri-phase composite materials having the chemical formula; 0.8[(1-x) SrCoO2.29+xCr2FeO4] + 0.2PZT, is synthesized to explore their energy storage capability. In this series, SrCoO2.29 and Cr2FeO4 ceramics are synthesized by using a sol-gel auto-combustion process while PZT is prepared by the solid-state method. The XRD analysis confirmed the formation of cubic crystal structure of the SrCoO2.29 and Cr2FeO4 and the rhombohedral phase of PZT. The SEM images exhibited an increase in average grain size with the incorporation and increasing contents of Cr2FeO4. The presence of all constituting elements with the exact stoichiometric ratio is validated through EDX analysis. Wide-range frequency-dependent dielectric behavior showed a dramatic fall in dielectric constant with increasing frequency. A same frequency dependent behaviour of ε'' and tanδ is witnessed as that of ε'. The investigation of electric modulus reveals that in the low-frequency region it possesses a trivial value which became significantly large with the increase of frequency. The presence of a relaxation peak in the plot of the imaginary part of the electric modulus plays a decisive role to distinguish the small and large range hopping mechanism. The complex impedance analysis revealed different electroactivity of composite material in the different frequency domains which made them viable for advanced energy storage devices working in the vast frequency range.

Analysis and characterization of opto-electronic properties of iron oxide (Fe2O3) with transition metals (Co, Ni) for the use in the photodetector application

There are several uses for ultraviolet photodetectors, including in the scientific, military, and industrial sectors. In this sense, UV photodetectors must have high responsiveness, be insensitive to visible light, and be inexpensive to produce. For this purpose, we report the development of Co and Ni based iron oxide nanoparticles via the cost effective low temperature sol–gel auto-combustion process. XRD study approves the cubic crystal structure of iron oxide (Fe2O3) with predominant orientation along (311) direction. A sharp and strong peak is obtained at 583 cm−1 and 594 cm−1 for both samples in FT-IR spectra assigned to metal oxide Fe–O network system which approves the formation of iron oxide. Raman spectroscopy analysis reveals the presence of two A1g and five Eg phonon modes in the case of both samples. Absorption study exhibits the strong absorption peaks for the iron oxide sample doped with cobalt and nickel, while poor absorption was noticed from the pure iron oxide nanoparticles. The large and low energy band gap values are found to be 2.77 eV and 1.68 eV for pure Fe2O3 and cobalt and nickel doped Fe2O3 nanoparticles, respectively. Stone and cloud-like shape morphology was observed from SEM analysis. The EDX spectra reveal the presence of essential elements, like Fe and O in the case of pure iron oxide while Fe, O, Co and Ni in the case of transition metals doped iron oxide nanoparticles. The photoluminescence (PL) spectroscopy technique was recorded the luminescent properties which reveals the decrease in PL intensity that confirms the decline in electron–hole recombination. Therefore, I–V characterization analysis reveals that electrical conductivity increases with the addition of metals due to decrease in electron–hole recombination with the co-doping of metals. These modified opto-electronic properties of the developed Fe2O3 by metals co-doping make it suitable candidate for the use in photodetector application.