Auto-combustion Method Research Articles

Investigation of structural, magnetic, and dielectric properties of BaFe12O19/Pr1−xSrxCoyMn1−yO3 composites; an emerging aspirant for high frequency applications

Abstract In this work, barium hexaferrite/perovskite BaFe12O19/Pr1-xSrxCoyMn1-yO3 composite ferrites were synthesized using single step sol–gel auto-combustion method. The lattice parameters and stabilized structural phases were studied using x-ray diffraction (XRD). The average crystallite size was found in the range of 51.6 nm–71.7 nm. Field Emission Scanning Electron Microscopy (FE-SEM) micrographs showed agglomerated particles having hexagonal as well as platelets like spherical shapes. Magnetic measurements done using vibrating sample magnetometer revealed that composite S3 (BaFe12O19/Pr0.75Sr0.25Co0.25Mn0.75O3) exhibits low saturation magnetization (35.3 emu g−1), and coercivity (775 Oe). Dielectric analysis revealed that, at 1 MHz frequency, the tangent loss (1.3) and dielectric loss (22.5) are highest for the composite S3 (BaFe12O19/Pr0.75Sr0.25Co0.25Mn0.75O3), whereas largest dielectric constant (20.7) was exhibited by S4 (BaFe12O19/Pr0.5Sr0.5Co0.5Mn0.5O3). Similarly, composite S2 (BaFe12O19/PrMnO3) (having the highest quality factor of 4.05) exhibited the largest resistivity (18885.8 Ω-cm), while composite S3 (BaFe12O19/Pr0.75Sr0.25Co0.25Mn0.75O3) showed highest AC conductivity (0.00125 (Ω-cm)−1). The investigated composites are found excellent choice for designing devices for applications involving high-frequency interference and electromagnetic shielding due to their unique magnetic and dielectric properties.

Mentioned Magnesium Oxide Nanomaterials for Effective Adsorption of Congo Red Dye and Fluoride Ions From Aqueous Solutions

This study investigates the synthesis of nanostructured magnesium oxide (MgO) using the auto-combustion method with urea (MgO-U), glycine (MgO-G), and citric acid (MgO-C) as fuels, followed by subsequent calcination. The selection of fuel plays a crucial role in determining the morphology of the nanostructures.X-ray diffraction (XRD) analysis confirms that the samples exhibit a well-crystallized structure with the desired phase and are free of impurities. Field emission scanning electron microscopy (FESEM) shows that MgO-U nanoparticles have diameters ranging from 10 to 20nm, MgO-C nanoparticles from 60 to 80nm, and MgO-G nanoparticles from 80 to 100nm. These MgO nanomaterials are specifically engineered for adsorption applications, aimed at removing toxic organic dyes and fluoride ions from aqueous solutions. Results demonstrate that MgO-G nanoparticles exhibit superior adsorption activity compared to MgO-U and MgO-C nanoparticles, with maximum uptake capacities of 1429 and 14mg/g, respectively. The adsorption processes adhere to second-order kinetic model. These findings highlight the potential application of the synthesized MgO nanoparticles for mitigating water pollution by adsorbing pollutants from aqueous media.

Structural, Dielectric, and Impedance Spectroscopic studies of (Zn0.4Mn0.4Ni0.2Ce0.2Fe1.8O4)1-x/(MWCNTs)x Nanocomposites for Future Energy Storage Applications

The novel Zn0.4Mn0.4Ni0.2Ce0.2Fe1.8O4 (ZMNCF) nanoparticles were first produced using the sol-gel auto-combustion method and then dispersed onto the surface of multi-walled carbon nanotubes (MWCNTs) with the aid of ultra-sonication and a series of different concentration of (ZMNCF)1-x/(MWCNTs)x; x = 0 – 20 wt. % nanocomposites were created. X-ray diffraction (XRD) analysis confirmed the Fd-3m space group and spinel structure of synthesized nanoparticles and revealed that the increasing concentration of MWCNTs has a great influence on the structural properties of the spinel ferrites. Transmission electron microscopy (TEM) was used to study the distribution, size and symmetry of nanoparticles and the accumulation of ZMNCF nanoparticles on the outer surfaces of MWCNTs. The estimation of different vibrational bands was examined using Fourier transform infrared (FTIR) spectroscopy. The dielectric and impedance measurements were studied in the frequency spectrum of 25 Hz to 2 MHz at room temperature. A detailed study of polarization mechanisms, Maxwell-Wagner model, and Koop’s theory and the effect of increasing concentration of MWCNTs on grain and grain boundaries have been discussed. The AC conductivity measurements conducted on the synthesized nanoparticles demonstrated an enhancement in conductivity upon the addition of MWCNTs. The percolation threshold for the nanocomposite was found to be between 10 and 15 wt. %, corresponding to a significant increase in conductivity due to the formation of a continuous conductive network. The valuable responses in dielectric properties showed that the synthesized nanocomposites could be used in future energy storage devices.

Synthesis and Characterization of Ni2+- Zr4+ Doped Ba-Ca M-Type Hexaferrites using Sol-Gel Auto-Combustion Method

This work aims to study the effect of Zr-Ni dopant on the structure and traits of M-type barium calcium hexaferrites (BaCaM). For the first time, Ba0.8Ca0.2ZrxNixFe12-2xO19 (0.0≤ x ≤1.0) samples are synthesized employing the SGACM (sol-gel auto-combustion method). The pure phase formation of BaCaM was established by XRD data Rietveld refinement. An augmentation in both the lattice parameters (‘a’ as well as ‘c’) owing to the higher ionic radii of dopant ions as compared to Fe3+ shows that Ni2+ and Zr4+ions were successfully swapped with Fe3⁺. The "c/a" ratio lies between 3.93-3.96 disclosing that the synthesized materials possess an M-type hexagonal ferrite structure. The reduction in crystallite with an increase in doping level might be due to lattice strain generated by the larger size of Ni2+ and Zr4+ dopant ions. The presence of two bands in the wavenumber range of 400 to 880 cm-1 in FTIR spectra corresponds to the Fe–O stretching in octahedral and tetrahedral locations. The Raman peaks widen without any shifting of the peak with an increment in Ni2+-Zr4+ ions contents revealing that Ni2+-Zr4+ are incorporated into BaCaM without changing its crystal structure. According to the M-H plots Ms value enhance from 24.94 (x= 0.00) to 36.84 emu/g (x= 0.60) and beyond x=0.60, Ms values drop with an increment in Ni2+-Zr4+substitution level. A broad coercivity range lies between 4858 Oe (x = 0.0) to 653 Oe (x = 1.0), decreasing monotonically with substitution in Ni2+-Zr4+. All the synthesized material exhibits a reduction in dielectric constant value as frequency increases. Ni-Zr-doped BaCaM materials could be a suitable candidate for magnetic recording media and microwave absorber applications.

AC Conductivity, Dielectric and Structural Properties of Co0.6Zn0.4-xMgxFe2O4 Co-Zn Spinel Nano Ferrites Prepared using Sol-gel Autocombustion Method

This study examined the structural, morphological, dielectric and AC conductivity properties of CoZnMg ferrite samples (Co0.6Zn0.4-xMgxFe2O4) with x = 0.00, 0.08, 0.16, 0.24, 0.32, 0.40. The sol-gel autocombustion method was used to synthesize the CoZnMg ferrite samples. The produced samples crystallize in the cubic spinel structure, according to an XRD analysis of the structural characteristics. The highly crystalline single-phase cubic spinel structure with a distinct peak in the (311) plane has been confirmed by XRD studies. The diameters of the crystallites have fluctuated between 24.92 and 9.80 nm. SEM, EDX and FTIR used to examine the morphological and elemental characteristics of the samples. According to FE-SEM, adding magnesium to the current ferrite system resulted in the loss of the porous gel structure. According to the relative stoichiometry of the Mg-substituted CoZn ferrite, the EDAX analysis verified the presence of Co, Zn, Mg and O. The investigated samples may be appropriate for a variety of uses, as indicated by the consistent conductivity at low frequencies. Within the frequency range of 100 to 5 MHz, the room temperature, electrical and dielectric properties were examined. The quantity of magnesium dopants and the microstructural features were related to the obtained results. The dielectric characteristics (ε′ and ε″) of the ferrites gradually decreased with frequency, even at higher frequencies. The samples exhibited interfacial polarization, which led to normal dielectric characteristics in line with the Maxwell-Wagner model.

Low-temperature reduction of NOx with NH3 using a hybrid system of non-thermal plasma-LaMn0.9CO0.1O3 perovskite nanocatalyst

The catalytic reduction of NOx at low temperatures presents a significant challenge, which can potentially be overcome by integrating plasma into the process. Porous perovskites emerge as promising catalysts for plasma-assisted NOx removal. In this study, perovskite catalysts LaMnO3 and LaMn0.9Co0.1O3 were synthesized using the auto-combustion sol-gel method with different fuels and subsequently evaluated for their efficiency in plasma-catalytic NOx removal in the presence of NH3. Analyses including XRD, BET, FESEM, TEM, FTIR, DRS, and TGA indicated that while the samples exhibited similar crystal sizes, they displayed varying levels of defects. Notably, the LaMn0.9Co0.1O3 catalyst synthesized with citric acid as the fuel (designated as LMC-Ci) demonstrated a highly porous and homogenous network structure, characterized by cubic-spherical particles measuring 20–30 nm, as corroborated by the XRD data. The co-substitution of cobalt in LaMnO3 enhanced light absorption, enabling the catalyst to effectively utilize ultraviolet photons produced by the plasma. Among the evaluated catalysts, LMC-Ci achieved the highest activity, resulting in a 98 % removal rate of NOx. The study further examined the influence of operational parameters, including discharge time, temperature, space velocity, and specific input energy, on the performance of the selected catalyst, revealing that plasma presence significantly reduced the operating temperature to 80 °C.

Structural and magnetic studies of Cobalt-Substituted copper ferrites for efficient photocatalytic dye degradation

In this work, cobalt-substituted copper ferrites with the composition CoxCu1-xFe2O4 (0.0 ≤ x ≤ 1.0) were synthesized using the sol–gel autocombustion method with citric acid as fuel. The influence of cobalt ion substitution (Co2+) on the structural, magnetic, optical, and photocatalytic properties was systematically studied. A range of characterization techniques, including X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), UV–visible spectroscopy, and vibrating sample magnetometry (VSM), were used to analyze the properties of the synthesized materials.XRD analysis revealed that the crystallite sizes of the samples ranged between 20–25 nm, with interplanar distances, bond lengths between cations, and crystallite size varying according to the degree of cobalt substitution. The formation of the spinel structure and the successful incorporation of cobalt ions into the lattice were confirmed by FTIR spectroscopy. Magnetic measurements showed that increasing the cobalt content enhanced the saturation magnetization while also influencing the Curie temperature and coercivity.The photocatalytic efficiency of the CoxCu1-xFe2O4 samples was evaluated for the degradation of Methylene Blue, Congo Red, and Malachite Green dyes under visible light irradiation. The photocatalytic degradation rates were strongly influenced by the copper-to-cobalt ion ratio, with cobalt-rich compositions demonstrating superior activity. The best photocatalytic performance was observed for intermediate cobalt concentrations (x = 0.4 and x = 0.6), where particle size and dielectric constant behavior led to efficient electron-hole separation and improved degradation rates. Methylene Blue decomposition was significantly enhanced in an alkaline medium (pH10) due to better adsorption and charge interaction between the dye and the photocatalyst surface. Fitting the experimental data to the Langmuir-Hinshelwood and Weibull models further highlighted the increased degradation rates with increasing pH and cobalt content, supporting the conclusion that cobalt-substituted copper ferrites are highly effective photocatalysts.

Characterization of Co1-xZnxFe2O4 nanoparticles synthesized by the autocombustion method

Nanosized particles of Co1-xZnxFe2O4, with x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1,0, were synthesized by the autocombustion method and characterized by X-ray diffraction (XRD) and ferromagnetic resonance (FMR). The results showed that the method can be used to produce particles with a crystallite size of less than 20 nm and that the anisotropy field of the particles decreases with increasing zinc concentration, ranging from 316 mT for Co0.6Zn0.4Fe2O4 to 31 mT for ZnFe2O4 (the anisotropy field could not be measured for CoFe2O4 and Co0.8Zn0.2Fe2O4). The present results may be useful for applications such as microwave absorption, hyperthermy, drug delivery and catalysis.

Tailoring structural, morphological, and magnetic properties of Sr0.54Ca0.46Fe6.5-xNixAl5.5O19 hexaferrites via Ni substitution

Sr0.54Ca0,46Fe6.5-xNixAl5.5O19 (0 ≤ x ≤ 0.3) hexaferrite powders were prepared by the sol-gel auto combustion method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Magnetic measurements were performed with physical properties measurement system (PPMS). The lattice parameters, volume, and lattice strain were calculated. XRD analyses revealed a reduction in crystallite size with increasing Ni content. Interestingly, the magnetic analysis indicated that nickel, with its low magnetic moment, significantly enhanced the magnetization of Sr0.54Ca0.46Fe6.5-xNixAl5.5O19 (0.0 ≤ x ≤ 0.3) and reduced the coercive field. Furthermore, the Law of Approach to Saturation (LAS) theory was employed to extract the first anisotropy constant, the anisotropy field, and several essential magnetic parameters, providing valuable insights into the magnetic behavior of samples.

Temperature-driven evolution of hematite (α-Fe2O3) nanoparticles: A study on structural, morphological and magnetic properties

This report explores the impact of annealing temperature on the structural and magnetic properties of hematite (α-Fe2O3) nanoparticles synthesized via the sol-gel auto-combustion method. The samples were annealed at 500 °C, 700 °C, and 900 °C, and characterized using XRD, FE-SEM, FT-IR, and VSM techniques. XRD analysis revealed an increase in crystallite size from 28.35 nm to 47.65 nm with temperature, accompanied by changes in lattice parameters, cell volume, and a reduction in dislocation density. Grain size distribution, observed via FE-SEM, showed a growth trend corresponding to the annealing temperatures, with sizes ranging from 114.8 nm to 167.8 nm. Energy dispersive X-ray spectroscopy (EDAX) verifies the elemental composition. FT-IR analysis revealed characteristic Fe-O vibrational bands between 430 and 525 cm⁻1, corresponding to Fe-O deformation in octahedral and tetrahedral sites. Subtle shifts in these bands with increasing temperature reflect structural changes in the nanoparticles. Magnetic characterization exhibited a decrease in saturation magnetization (MS) from 2.96 emu/g at 500 °C to 0.74 emu/g at 900 °C, while coercivity (HC) increased from 643.2 Oe to 1161.1 Oe, reflecting the influence of temperature on the magnetic domain structure. The observed relationship between the structural evolution and magnetic behavior underscores the potential of annealing to optimize α-Fe₂O₃ nanoparticles for use in magnetic storage, environmental remediation and multifunctional biomedical applications.

Improved structural and dielectric traits of Cd-Zn spinel ferrites by co-substitution of La3+ and Er3+ cations

In the present work, the effect of co-doping of rare earth (Re3+), La and Er cations on the physical and dielectric performance of Cd-Zn spinel ferrites fabricated by sol-gel auto combustion method is reported. The prepared ferrites were doubly calcinated at 550 ℃ and 750 ℃ for 2 hours and 8 hours, respectively. The obtained samples were investigated using XRD, FTIR and dielectric measurements. XRD powder patterns verified the single-phase growth of spinel structure of all the as-synthesized ferrites with Fd-3m space group. The obtained results revealed that the Lattice constant reduces with increasing Er3+ concentrations, while crystallite size showed increasing behavior with increasing Er3+ concentration. FTIR results revealed the existence of two major absorptionbands i.e. low frequency bands in range 405-428 cm-1 and high frequency bands in range 523- 550 cm-1 which are evidence of spinel structure formation. LCR measurements are used to investigate the impact of co-doping of La3+ and Er3+ on the various dielectric parameters of prepared samples in response to frequency. Dielectric constant and loss decreased with the incorporation of Er3+, while an increase in ac conductivity was observed. The observed properties reveal that the prepared materials are suitable candidates for application in the high-speed microwave and radio frequency devices.

Effect of La concentration on phase formation, local structure and optical properties of Sr1-xLaxTiO3 nanoparticles

The objective of this paper is to give information about phase formation, local structure and optical characteristics measured of the Sr1-xLaxTiO3 (x = 0–0.10; SLTO) nanoparticles. These nanoparticles have been synthesized by microwave-assisted sol-gel auto combustion method. Experimentally, the structural information was gathered by using the X-ray diffractometer and showed a pure phase with cubic perovskite structure of all samples. As well, the crystallite size and particle size of the SLTO samples decreased as the La doping content increased. The micro-strain (varying between 0.63×10−3 and 1.48×10−3) produced in the samples through Williamson-hall plot. The optical properties were determined using UV–Vis spectrophotometer. The band gap (Eg) was determined for all samples to be 4.10 eV. The study of local structure was performed by utilizing the synchrotron radiation X-ray absorption near edge structure (XANES) technique. The analyses XANES spectra clearly showed that the oxidation state of Sr, La and Ti ions are +2, +3 and + 4, respectively. The clear agreement between measured and calculated XANES spectra was the strongest evidence of La atoms occupies A-site (Sr) in SrTiO3 structure.

Controllability of optical, electrical, and magnetic properties of synthesized Cd-doped MgFe2O4 nanostructure

This study explores the synthesis of cadmium-magnesium co-doped magnesium ferrite (Mg1+xCdxFe2–2xO4, 0.00 ≤ x ≤ 0.30, Δx = 0.05) via a citric acid-assisted sol-gel auto-combustion method. X-ray diffraction (XRD) analysis revealed crystal structure changes due to Cd and Mg co-doping, with the 0.25 Cd sample showing the smallest crystallite size and highest lattice strain. High-resolution transmission electron microscopy (HRTEM) confirmed the nanostructure and largest surface area for this sample. Diffuse reflectance spectra, analyzed using the Kubelka-Munk relation, indicated that the 0.25 Cd sample had the lowest energy gap (2.08 eV), supported by band position calculations. Electrical conductivity and charge transport mechanisms were examined at various temperatures. Magnetization studies showed reduced saturation magnetization at x = 0.25, ascribed to cation distribution changes and spin canting, with coercivity and anisotropy decreasing with higher Cd content. Overall, the 0.25 Cd sample exhibited optimized optical, electrical, and magnetic properties due to its distinct microstructure.

Improved ionic conductivity of La and Mg co-doped ceria nanocrystals synthesized by auto-combustion method

Ionic conductivity of La3+ and Mg2+ co-doped ceria, synthesized by auto-combustion method, is investigated here as electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFCs, operating below 800 °C). The prepared nanocrystalline electrolytes, LMDC10 (Ce0.9La0.05Mg0.05O2-δ) and LMDC20 (Ce0.8La0.1Mg0.1O2-δ) have exhibited improved ionic conductivities of 1.31 × 10−2 and 1.39 × 10−1 S cm−1 at 1073 K with reduced activation energies of 0.93 and 0.97 eV, respectively, when compared to conventional electrolytes like yttria-stabilized zirconia. The prepared samples are characterized by XRD, Raman spectra, XPS and FESEM which confirmed the formation of single-phasic cubic fluorite structure. Thus, the potential for La3+ and Mg2+ co-doped ceria electrolytes to offer cost-effective alternatives with low sintering temperatures and high performance for IT-SOFCs.

Transport and magnetic properties of [formula omitted]/Graphene nanoplatelets nanocomposites

A series of Zn0.5Co0.25Cu0.25Ho0.037Fe1.963O4 (ZCCHF)/Graphene nanoplatelets (GNPs) nanocomposites (where GNPs = 0 wt%, 1.25 wt%, 2.5 wt%, 3.75 wt%, 5 wt%) were prepared via sol-gel auto-combustion (SGAC) method followed by bath sonication and studied their structural, morphological, optical, dielectric, and magnetic properties. The structural analysis confirmed a single-phase crystal matrix of all the as-prepared nanocomposites. The optical analysis revealed that the energy bandgap (Eg) lies within the range of 1.57 eV–1.62 eV. The dielectric analysis showed that the improvement in the dielectric constant (ε′) and reduction in dielectric tangent loss (tan δd) with increasing GNPs concentration from 0 wt% to 5 wt%. The real part of permeability (μ′) was improved and magnetic tangent loss (tan δM) was reduced with the addition of GNPs. Magnetic properties were studied at different temperatures (5 K, 300 K, and 400 K), and observed high saturation magnetization (MS), and coercivity (HC) at a low temperature (at 5 K). The low MS, and HC values were observed at high temperatures (300 K and 400 K). The combination of improved dielectric and tunable magnetic properties makes ZCCHF/GNPs nanocomposites promising candidates for applications in spintronics, high-frequency magnetic devices, and advanced electronic systems.

Cerium doped superparamagnetic Mn-Zn ferrite as a promising material for self-regulated magnetic hyperthermia

Recently, cubic ferrites (CF) have been widely explored in biomedical applications, especially those that display superparamagnetism behavior due to the desirable absence of remanent field. In this study, we report the self-stabilization of the magnetic fluid hyperthermia (MFH) temperature in the cancer therapy range (42 - 48 ºC) by Ce3+ substitution in superparamagnetic Mn0.8Zn0.2Fe2-xCexO4 ferrite with x = 0.0; 0.015; 0.030; 0.050 and 0.100. A comprehensive characterization was performed in order to investigate the influence of this replacement on the magnetic and structural properties of the ferrite. The samples were synthesized by the sol-gel auto-combustion method and the properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), Raman spectroscopy (RS), Mössbauer spectroscopy (MS), vibrational sample magnetometry (VSM), and ferromagnetic resonance (FMR). Magnetic hyperthermia essays were used to obtain the heat induction curves and calculate energy dissipation. We refined the XRD data by the Rietveld method to determine the cation distribution and calculate interionic parameters. Magnetic characterization confirms the superparamagnetic behavior at 300 K, which is expected from the TEM results that show a narrow distribution of particle sizes, with a mean size of about 6.5 nm for all samples. The VSM results show a consistent decrease in magnetization saturation with cerium content that result in a weaker self-heating induction capacity for the cerium-doped samples. FMR results also show a smaller relaxation time T2 for these samples, suggesting a slower energy dissipation rate. These conclusions are confirmed by the heat induction curves and the values of the specific absorption rate (SAR), which are smaller for cerium-doped samples. For the a field with an amplitude of 35.33 kA/m and a frequency of 222 kHz, the temperature of the cerium-doped samples saturates in the optimum interval for cancer treatment, between 42 and 48 ºC. These results suggest that Ce3+ is a promising doping ion to optimize the heating rate behavior of Mn-Zn ferrite for cancer treatment by hyperthermia.

Effect of Li1+ ion on the physico-chemical properties cation distribution of sol-gel synthesized Ni-Zn spinel ferrite nanoparticles

This study presents the synthesis and comprehensive analysis of polycrystalline LixNi0.6Zn0.4-2xFe2+xO4 (with x values of 0.00, 0.01, 0.03, 0.05, 0.07, 0.09) ferrites, with lithium (Li) concentrations ranging from x = 0.00 to 0.09, utilizing the sol-gel auto-combustion method followed by sintering at 800 °C for 8 h. A nuanced examination of the lattice constants obtained from the X-ray diffraction patterns revealed a slight decrement from 8.386 to 8.357 Å, exhibiting a linear pattern across the Li concentration spectrum. The crystallite sizes, as determined by the Scherrer formula, fluctuated between 31 and 40 nm, while Field Emission Scanning Electron Microscopy indicated an increase in average grain size from 146 to 186 nm due to nanoparticle agglomeration. High-Resolution Transmission Electron Microscopy analysis of nanoparticles yielded an average grain size of ∼69 nm and an interplanar spacing of approximately 0.1521 nm. Magnetic characterization revealed a decrease in saturation magnetization from 87 to 70 emu/g with increasing Li content, with the lowest Ms observed for the x = 0.09 sample, indicating the material's soft magnetic nature. Raman and Fourier-transform infrared spectroscopy confirmed the retention of the conventional spinel structure, characterized by both tetrahedral and octahedral iron coordination, and illuminated the impact of co-existing iron phases on the structural anomalies observed. These findings contribute valuable insights into the effects of lithium substitution on the structural, morphological, and magnetic properties of Ni-Zn ferrites, underscoring their potential for various technological applications.

Synthesis, characterization, magnetic and morphological properties of poly(m-phenylenediamine)/ZnCoFe2O4 nanocomposites

In this work, poly(m-phenylenediamine) (PmPD)/ZnCoFe2O4 nanocomposites (NCs) were synthesised by in-situ chemical oxidative polymerisation method. The ZnCoFe2O4 nanoparticles (NPs) were prepared by auto-combustion method. The crystalline size of PmPD/ZnCoFe2O4 NCs and ZnCoFe2O4 NPs were calculated using the Powder X-ray diffraction (XRD) analysis. The functional group of the samples was analysed by Fourier transform infrared spectral (FTIR) analysis. The XRD and FTIR results were clearly indicated that the formation of PmPD/ZnCoFe2O4 NCs. The spherical morphology of the PmPD/ZnCoFe2O4 NCs was confirmed through Field emission electron microscopy (FESEM). The magnetic hysteresis (M-H) loops of ZnCoFe2O4 NPs and PmPD/ZnCoFe2O4 NCs were revealed their ferromagnetic behaviour. Thermogravimetric analysis (TGA) was indicated that thermal stability of PmPD/ZnCoFe2O4 NCs increases with increase in concentration of ZnCoFe2O4 NPs. The dielectric properties of PmPD/ZnCoFe2O4 NCs were also examined with different frequency.

Efficient photodegradation of acid orange 7 in water using a facile ultrasound-assisted microwave-combustion synthesized Ag-ZnAl2-xFexO4 solid-solution photocatalyst

This study explores the development of Ag-ZnAl2-xFexO4 solid-solution photocatalysts for Acid Orange 7 (AO7) degradation under visible light irradiation. The microwave auto-combustion method was employed to synthesize these photocatalysts, allowing for the investigation of the influence of Fe substitution (x) on their properties and performance. Characterization techniques revealed a trade-off between Fe content, surface area, pore size, and light absorption capacity. The Ag-ZnAlFeO4 variant achieved an optimal balance, demonstrating exceptional photocatalytic activity for AO7 degradation. This optimized photocatalyst achieved a removal efficiency of 99.3 % under neutral pH conditions, highlighting its effectiveness and potential for practical applications. Interestingly, the mineralization efficiency of AO7 reached 85.2 % after 160 minutes of reaction time. Kinetic studies supported the superior performance of Ag-ZnAlFeO4, attributing its success to its favorable morphology, high surface area, strong light absorption, and minimal electron-hole pair recombination. The proposed degradation mechanism involves light absorption, generation of electron-hole pairs, and their subsequent reactions with water and oxygen molecules to degrade AO7. This work establishes Ag-ZnAl2-xFexO4, particularly Ag-ZnAlFeO4, as a promising visible-light photocatalyst for the efficient degradation of organic pollutants.

Synthesis, characterisation and functionalization of Hercynite nanoparticles for improved antibacterial activity

Hercynite i.e.,FeAl2O4 is an earth-abundant spinel mineral with a cubic crystal structure and belongs to the normal spinel ferrites possessing optical absorption in the visible range as well as superior magnetic and thermal properties. Herein, we synthesized nanosized FeAl2O4 where the citric acid-mediated sol–gel auto-combustion method was employed to achieve its pure phase and studied its physicochemical properties. Furthermore, the superior colloidal dispersion stability of the FeAl2O4 nanoparticles was achieved required for antibacterial activity and standardised via post-synthesis surface functionalisation using amino-propyl-triethoxysilane (APTES). We further characterised the material using states of art characterisation techniques for their structural, morphological, optical and thermal properties. Finally, the antibacterial activity of pure and surface functionalised FeAl2O4 nanoparticles was investigated against the Escherichia coli (E. coli) strain. We observed good penetration of surface functionalised FeAl2O4 nanoparticles into the bacterial membranes due to the high degree of dispersion achieved via cationic surface charge. Conclusively, a key finding of this study is the enhanced antibacterial properties of surface functionalised FeAl2O4 nanoparticles for the concentration of 31 µg/mL compared to pure FeAl2O4 nanoparticles at 62 µg/mL. This study has great relevance in the area of wound healing and tissue regeneration in the future.