Spinel Ferrite Nanoparticles Research Articles

Low-temperature sol–gel synthesis of magnetite superparamagnetic nanoparticles: Influence of heat treatment and citrate–nitrate equivalence ratio

Spinel ferrite nanoparticles are a remarkably versatile group of metal oxides with unique magnetic and electronic properties, making them promising candidates for certain electronic, biomedical, and environmental applications. Magnetite nanoparticles are obtained using complex synthesis methodologies that require inert atmospheres, additives to induce pH changes, expensive or toxic reagents, or complex equipment. In this work, a new approach to obtain superparamagnetic magnetite nanoparticles using citrate–nitrate sol–gel synthesis followed by heat treatment is presented. Iron nitrate and citric acid were added in different equivalence ratios (χ) (citrate/nitrate = 0.30, 0.85, and 1.40). The thermal behaviour of the xerogels was evaluated using thermal analysis techniques, and the results indicated that decreasing the equivalence ratio decreased the temperature required for magnetite formation, and the different release rates of reducing gases influenced the properties of the final material formed. The heat-treatment temperatures for the synthesis with the optimal χ were 130, 150, and 170 °C for 2, 4, and 8 h. Each condition was characterised in terms of the structure and magnetic properties of the product. The results showed that the prepared iron oxide nanoparticles were in the magnetite phase (Fe3O4) and possessed a crystallite size of 4.5–6.0 nm and average particle size of <10 nm. The magnetite nanoparticles displayed superparamagnetic behaviour, with a saturation magnetisation of up to 26.24 emu/g and remanent magnetisation of almost zero. Therefore, these superparamagnetic magnetite nanoparticles have excellent potential for biomedical and environmental applications.

Study of lanthanum ions (La3+) doped Manganese-Cobalt (Mn-Co) based spinel ferrite nanoparticles for technological applications

Study of lanthanum ions (La3+) doped Manganese-Cobalt (Mn-Co) based spinel ferrite nanoparticles for technological applications

Effect of embedding aluminium and yttrium on the magneto-optic properties of lanthanum spinel ferrite nanoparticles synthesised for photocatalytic degradation of methyl red

Effect of embedding aluminium and yttrium on the magneto-optic properties of lanthanum spinel ferrite nanoparticles synthesised for photocatalytic degradation of methyl red

Tuning the Structural and Magnetic Properties of the Stuffed Framework Structures MeFe2O4 (Me = Ni, Ca, and Sr)

Spinel ferrite nanoparticles (NPs), have received a lot of attention in medical applications. Therefore, facile synthesis of ferrite NPs of numerous shapes and sizes using the citrate autocombustion technique was utilized in this article. A series of ferrite with the general formula MeFe2O4 [Me = nickle (Ni), calcium (Ca), and strontium (Sr)] are synthesized with varying average ionic radii and cation disorder on the A-site. The structural and morphological characterization of the prepared samples was performed using XRD, HRTEM, FESEM, EDAX, XPS, and Raman analyses. The phase transformation from cubic (Ni) to orthorhombic (Ca) to monoclinic (Sr) was also revealed by XRD. Accordingly, HRTEM images demonstrated nanoparticles in orthorhombic and monoclinic shapes, which are inconsistent with XRD analyses. The coercive field HC for monoclinic SrFe2O4 is ≈ 42 times larger than the Hc for NiFe2O4 with a cubic structure. This deviation in HC compared to the cubic shape particles can be coupled to the shape anisotropy present in SrFe2O4 and refers to the presence of a preferred magnetization direction within the material. The use of monoclinic SrFe2O4 NPs as antifungal activity agents is noteworthy due to their advantages in terms of surface area, efficacy, and biodegradability.

Structural parameters, energy states and magnetic properties of the novel Se-doped NiFe2O4 ferrites as highly efficient electrocatalysts for HER

This study is devoted to NiFe 2 O 4 with different masses of Se (NFO + x%Se) (x = 0.0–4.0%) spinel ferrite nanoparticles production and investigation. The results of the crystal structure, microstructure and magnetic properties are presented as a function of the chemical content of the NFO + x%Se. Superparamagnetic (at 300 K) and ferrimagnetic (at 10 K) states are observed for all samples in the wide magnetic field range. The field dependencies of the magnetization show that Se-substitution does not change the main magnetic characteristics when x<2.0%. We observe a non-linear dependence of magnetic parameters for sample with x ≥ 2.0% (for NFO+2%Se, we determine the increase of the main magnetic parameters for 20% of the average values and the minimum values belong to the NFO+3%Se). The undoped sample and NiFe 2 O 4 +x%Se are soft magnets and characterized by the low coercivity (varying in the range 560–647 Oe). At T = 10 K squareness ratio (Sq. = Mr/Ms) is in a range of (0.216–0.318). This indicates a preferable single-domain state of crystallites, which differs from the magnetic structure at T = 300 K. Furthermore, the NFO + x%Se (x = 2.0) have a low overpotential of about −327 mV, and a small Tafel slope of 91 mV/dec, which makes it a better for HER (hydrogen evolution reaction) catalyst than the undoped NiFe 2 O 4 .

Structural and Electrical Properties of Pure and Samarium Doped MgFe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Nanoparticles for Resistive RAM Applications

Spinel ferrites nanoparticles have attracted the attention of researcher for memory storage devices. We have synthesized MgFeO4 pure sample and MgFe1.8Sm0.2O4 doped sample via solgel technique. The study of structural, electrical, dielectric, and I-V properties were studied of synthesized spinel magnesium ferrites nanoparticles. X-ray diffraction (XRD) confirmed the spinel structure of both compositions. The frequency dependent AC conductivity, dielectric constant, dielectric tangent loss, was studied in the range of 20Hz to 3MHz. I-V measurements has been done for the resistive switching properties. I-V curves of both compositions in the current study exhibits the formation of hysteresis loop. The hysteresis loop behavior shows that with the addition of samarium the trend of loop increases which plays crucial role as a Resistive Random-Access Memory (ReRAM) application in switching memory storage devices.

Effect of Ni substitution and annealing temperature on structural and magnetic properties of MnZn-Ferrites: Cytotoxicity study of ZnO and SiO2 coated core shell structures

Magnetic spinel ferrite nanoparticles (NPs) have a broad scope of applications based on their structural properties, including in lithium-ion batteries, catalysts, electrochemical energy storage, drug delivery, magnetic hyperthermia, and photothermia. In this study, we investigated the structure, crystallographic phase formations, and magnetic properties of Ni-substituted MnZn ferrites (MZFs), Mn(0.6-x)Zn(0.4-y)Ni(x+y)Fe2O4 (x = 0–0.6, y = 0; y = 0–0.4, x = 0) compositions of as-prepared (AP) and air annealed (350–1200 °C) samples. All AP NPs exhibited a pure spinel structure. Ni-MZF compositions annealed at 600 °C had high α-Fe2O3 secondary phase content in Ni-MZFs (Ni substituted for Zn), whereas Ni-MZFs with x = 0.4 (Ni substituted for Mn) had no impurities, and its magnetization (50 emu/g) was enhanced compared with that of the other samples. X-ray photoelectron spectroscopy revealed that Fe3+ cations were present in tetrahedral and octahedral sites. The single spinel phase reappeared with improved crystallinity in all Ni-MZFs by annealing at 1200 °C and exhibited superior magnetization (60–73 emu/g) compared with that of MZF (35 emu/g). Additionally, the spinel phase was stabilized in the ZnO- and SiO2-coated Ni-MZF core shell structures annealed at 700 °C with higher magnetization than MZF. Moreover, Ni-MZF core shell structures exhibited biocompatibility and may have biomedical applications.

Theranostic Applications of an Ultra-Sensitive T1 and T2 Magnetic Resonance Contrast Agent Based on Cobalt Ferrite Spinel Nanoparticles.

Simple SummaryMagnetic nanoparticles (MNPs) represent an important class of nanomaterials that has been actively employed in multiple technological applications. The MNPs and their based composites have been intensively developed for magnetic resonance imaging, targeted drug delivery, magnetic hyperthermia, and other applications. Magnetic Resonance Imaging (MRI) has a prominent position among clinical imaging modalities as it allows for high spatial resolution and tissue specificity without harmful ionizing radiation. The aim of the study was the demonstration of the potential use of magnetic nanoparticles based on cobalt ferrite spinel as advanced MRI contrast agents that are capable of both T1-weighted positive and T2-weighted negative contrast enhancements in vitro and in vivo. Furthermore, in the present study, we combined novel physical, chemical, and biomedical approaches to develop a multifunctional MRI-detectable drug delivery system that was an efficient T1- and T2-weighted MRI contrast agent and a nanocarrier for targeted drug delivery in vivo.Nano-dimensional materials have become a focus of multiple clinical applications due to their unique physicochemical properties. Magnetic nanoparticles represent an important class of nanomaterials that are widely studied for use as magnetic resonance (MR) contrast and drug delivery agents, especially as they can be detected and manipulated remotely. Using magnetic cobalt ferrite spinel (MCFS) nanoparticles, this study was aimed at developing a multifunctional drug delivery platform with MRI capability for use in cancer treatment. We found that MCFS nanoparticles demonstrated outstanding properties for contrast MRI (r1 = 22.1 s–1mM–1 and r2 = 499 s–1mM–1) that enabled high-resolution T1- and T2-weighted MRI-based signal detection. Furthermore, MCFS nanoparticles were used for the development of a multifunctional targeted drug delivery platform for cancer treatment that is concurrently empowered with the MR contrast properties. Their therapeutic effect in systemic chemotherapy and unique MRI double-contrast properties were confirmed in vivo using a breast cancer mouse tumor model. Our study thus provides an empirical basis for the development of a novel multimodal composite drug delivery system for anticancer therapy combined with noninvasive MRI capability.

A Review: Nanoparticles NiFe2O4 Synthesis and Its Application as Hyperthermia Agents in Biomedicine

&#x0D; Nickel ferrite (NiFe2O4) is one of the spinel ferrite nanoparticles that is useful for scientific and technological, like biomedicine. This paper discusses the synthesis of NiFe2O4 nanoparticles by various methods. This paper aims to find out the most efficient method for the synthesis of NiFe2O4 nanoparticles which are used as hyperthermia agents in biomedicine. The method used is a literature study of an article with publications from 1956-2018 by discussing several methods of NiFe2O4 syntheses, such as sol-gel, hydrothermal, co-precipitation, and combustion. From these methods, it was found that co-precipitation is the most efficient method among the other methods because it produces a relatively small NiFe2O4 nanoparticle size, which is 28 nm, causing these small particles to tend to be superparamagnetic and is good to be used as hyperthermia agent in biomedicine. This study is expected to be used as a reference to determine the method for synthesizing NiFe2O4 nanoparticles.

Structural, morphological and photocatalytic properties of Ni-Mn ferrites: Influence of the Ni:Mn ratio

Mixed Ni-Mn ferrite spinel nanoparticles embedded in SiO 2 matrix were prepared by sol-gel method, followed by annealing at 300 and 1000 °C. The thermal analysis and Fourier transform infrared spectroscopy confirmed the formation of Ni-, Mn- and Co- malonate precursors and their decomposition to ferrites. The X-ray diffraction data showed the presence of poorly crystallized Ni-Mn ferrite at 300 °C and of Ni-Mn ferrite accompanied by α-Fe 2 O 3 , cristobalite, quartz and Fe 2 SiO 4 . at 1000 °C. The transmission electron microscopy revealed spherical shape ferrite particles of 19–46 nm diameter, that increase with the increase of Ni content and annealing temperature. For the samples with low Ni content, the pores are larger, their size reaching 100 Å, while for the samples with high Ni content the pores are smaller, their size being lower than 50 Å. The specific surface area increases with the increase of Ni content up to 0.7/0.3 Ni/Mn ratio and after remains constant. The isotherms were used to calculate the rate constants for the decomposition of malonate precursors to ferrites and the activation energy for each ferrite. The samples show a broad response in both UV and visible range, with the maximum in visible domain. Ni 0.5 Mn 0.5 Fe 2 O 4 sample shows the best sonophotocatalytic activity against Rhodamine B solution under visible light irradiation. The prepared Ni-Mn ferrites may have potential application for water and wastewater decontamination. • Ni 0.5 Mn 0.5 Fe 2 O 4 shows the best sonophotocatalytic activity against RhB solution. • In samples with low Ni content, the pore size reaches 100 Å. • In samples with high Ni content, the pore size is lower than 50 Å. • The specific surface area of the samples increases with the increase of Ni content.

Bi3+ and V3+ co-substituted Ni-Co spinel ferrites: Synthesis, optical, magnetic characterization and hyperfine interaction

Ni0.5Co0.5VxBixFe2-2xO4 spinel ferrite nanoparticles with composition (x = 0.00, 0.02, 0.04, 0.06 and 0.08) (CoNiVBiFeO (x = 0.00–0.08) SFNPs) were well fabricated hydrothermally. The consequence of co-substitution of both Bi3+ and V3+ ions on structure, morphology, and magnetic features of Ni0.5Co0.5Fe2O4 SFNPs were studied using XRD (X-ray diffractometry), scanning (SEM) and transmission (TEM) electron microscopies along with EDX, XPS (X-ray photoelectron spectroscopy), VSM (vibrating sample magnetometry) and Mossbauer spectroscopic techniques. The pure spinel ferrite (SFs) phase was approved via XRD. The morphology of SFNPs were revealed by SEM and TEM. Hyperfine parameters are determined from fitting room temperature Mössbauer spectra. The V3+ and Bi3+ ions occupy mainly at B site. The isomer shift values are coupled with the characteristics of the high spin Fe3+ ion. The influence of V3+ and Bi3+ ions co-doping on the magnetic features of Ni-Co SFNPs has been also investigated at 300 and 10 K. The saturation magnetization (Ms), remanence (Mr), coercive field (Hc), and Bohr magneton number (nB) are extracted from the recorded M-H hysteresis loops. Nanomagnetic materials with x content of 0.02, 0.08, and 0.10 exhibited superparamagnetic (SPM) behavior, whereas other products with x content of 0.00, 0.04, and 0.06 displayed soft ferrimagnetic behavior at ambient temperature. The different prepared nanoferrites displayed hard ferrimagnetic characteristic at 10 K. The Ms and Mr values are decreased as result of V3+ and Bi3+ ions co-doping. However, Hc does not show a monotonic trend. The fluctuations in magnetic moments of ions, super-exchange coupling, and distribution of cations are correlated with the changes in magnetic parameters to explain their variations.

Palladium decorated nickel and zinc ferrite spinel nanoparticles applied in aniline synthesis – development of magnetic catalysts

Aniline is one of the most important chemical in the polyurethane industry and it is produced by the catalytic hydrogenation of nitrobenzene. The development of novel, multifunctional catalysts, which are easily recoverable from the reaction mixture is therefore of paramount importance. Transition metal-containing ferrites decorated with palladium were prepared by using a combination of sonochemical and combustion steps. First of all, magnetic ferrites were produced to be used in catalyst preparation as supports for palladium nanoparticles. On the surface of the ferrite particles palladium nanoparticles were deposited by applying ultrahigh sonication in an alcoholic phase. All in all, three magnetic catalysts, Pd/NiFe2O4, Pd/ZnFe2O4, and Pd/NiZnFeO4 have been created. The catalysts have been tested and their activity have been compared in nitrobenzene hydrogenation to synthesize aniline at four different temperatures, and 20 bar pressure. The most active catalysts were the Pd/ZnFe2O4 and Pd/NiZnFeO4 systems with which aniline yields of 99.2 and 92.8 n/n% were achieved after 3 h of hydrogenation, respectively. In contrast, by applying the Pd/NiFe2O4 catalyst, a significantly lower aniline yield was achieved. It was proved that, due to their magnetic properties, the prepared catalysts are easily removable from the reaction medium by using a magnetic field. Thus, catalysts with excellent properties have been successfully developed and tested in nitrobenzene hydrogenation.

Monte Carlo study on size-dependent radiation enhancement effects of spinel ferrite nanoparticles

This study investigates the effect of adding spinel ferrite nanoparticles to tissues irradiated with low energy photons and simulated effect of particle size on dosimetry quantities. The simulations have been carried out with MCNP 6.2 code which enables event-by-event electron transport. Firstly, dose enhancement factors have been determined with water/ferrite mixture and for MnFe2O4, CoFe2O4, Fe3O4, NiFe2O4, ZnFe2O4, at 5,10, and 20 mgg−1 concentrations and individual nanoparticles of Fe3O4 in a 1 cm3 volume. Source photons used were iodine-125 spectrum and X-rays spectra with tube voltages 50 kVp, 100 kVp. The dose enhancement with 50 kVp source go as high as 1.73 with 20 mgg−1 NP concentration, whereas with 100 kVp source, it drops to 1.13 with 5 mgg−1. In a different simulation, an endothelial cell of tumor vasculature with nanoparticles attached to its surface has been modeled to handle the cellular level effects. The amount of self-absorption versus absorption in the cell has been compared for different particles size. Also, we presented the electron spectrum leaving the nanoparticle surfaces entering the cell volume. To achieve realistic dose enhancement for the macro scale, either high concentrations or very low photon energies are required. In the cellular scale simulations, results indicate an extraordinary difference in low energy electron spectrum, which contribute much to energy deposition within the vicinity of nanoparticles, showing the importance of targeting.

Improved magnetic and electrical properties of transition metal doped nickel spinel ferrite nanoparticles for prospective applications

Mn2+ and Cr3+ co-doped nickel ferrite nanoparticles are synthesized via cost effective and eco-friendly chemical co-precipitation method. The work reports sequentially the influence of dopants on the structural, electrical and magnetic properties of nickel ferrite for potential applications. The inverse spinel structure with face centered cubic structure is confirmed using X-ray diffraction analysis. The lattice constants increased because of larger size of metal ions as compared to that of iron ions. The crystallite size calculated using Sherer formula from XRD pattern are in the range of 17–31 nm. The morphology of doped samples changed slightly as confirmed from scanning electron microscopy (SEM). The parameters like dielectric constant, dielectric loss, alternating current conduction and impedance show normal behavior of ferrite in the range of 1 MHz–3 GHz. The dielectric constant (3.01), dielectric loss (0.09) and alternating current conduction (0.80 × 10−2 Ω−1 cm−1) of co-doped nickel ferrite exhibited lower values at dopant content of x,y = 0.2 and then starts to increase while the impedance showed reverse trend. The magnetic measurements showed enhanced saturation magnetization (24.5 emu/g) and decrease in coercivity up to 30.3 Oe with changing dopants concentration. The x, y = 0.1, and 0.2 composition exhibited optimum values of dielectric constant, dielectric loss, alternating current conduction and coercivity while high values of electrical impedance and saturation magnetization. Therefore, the synthesized material with nominal composition Ni0.9Mn0.1Fe1.9Cr0.1O4 and Ni0.8Mn0.2Fe1.8Cr0.2O4 can be successfully used for applications in magnetic devices, microwave frequency devices and transformer cores.

Remarkable catalysis of spinel ferrite XFe2O4 (X = Ni, Co, Mn, Cu, Zn) nanoparticles on the dehydrogenation properties of LiAlH4: An experimental and theoretical study

Safe, compact, lightweight and cost-effective hydrogen storage is one of the main challenges that need to be addressed to effectively deploy the hydrogen economy. LiAlH4, as a solid-state hydrogen storage material, presents several advantages such as high hydrogen storage capacity, low price and abundant sources. Unfortunately, neither thermodynamic nor kinetic properties of dehydrogenation for LiAlH4 can fulfill the requirements of practical application. Thus, a series of spinel ferrite nanoparticles such as XFe2O4 (X = Ni, Co, Mn, Cu, Zn, Fe) were prepared by using the modified thermal decomposition method, and then doped into LiAlH4 by using ball milling. Our results show that LiAlH4 doped with 7 wt% NiFe2O4 starts to release hydrogen at 69.1 °C, and the total amount of hydrogen released is 7.29 wt% before 300 °C. The activation energies of the two-step hydrogen release reactions of LiAlH4 doped with 7 wt% NiFe2O4 are 42.32 kJ mol−1 and 71.42 kJ mol−1, which are 59.0% and 63.6% lower than those of as-received LiAlH4, respectively. Combining the density functional theory (DFT) calculations, we reveal that both the presence of NiFe2O4 and in-situ formed Al4Ni3 in ball-milling decrease the desorption energy barrier of Al-H bonding in LiAlH4 and accelerate the breakdown of Al-H bonding through the interfacial charge transfer and the dehybridization of the Al-H cluster. Thus, the experimental and theoretical results open a new avenue toward designing high effective catalysts applied to LiAlH4 as a candidate for hydrogen storage.

Plant‐Mediated Green Synthesis of Magnetic Spinel Ferrite Nanoparticles: A Sustainable Trend in Nanotechnology

AbstractNanotechnology is very important in developing sustainable technologies for the future. Increased demand for metal and metal oxide nanoparticles has led to their large‐scale production using conventional chemical methods with various toxic solvents. These techniques produce poisonous and harsh products that present a biological risk to the environment and have terrible effects on the life of microbes, plants, vertebrates, and invertebrates at different trophic levels. Thus eco‐friendly “green” synthesis methods have become necessary to synthesize nanoparticles using biological entities, such as plants and microorganisms. When compared to other methods, “green” synthesis is safer for human health and the environment. Plants, the main factory for the green synthesis of nanoparticles, have been used extensively for this purpose. This review, focuses on eco‐friendly synthesis to design spinel ferrite nanoparticles, particularly, using extracts from plant products that act not only as precursors but also as reductants and stabilizers during the synthesis process. The outstanding features of these nanoparticles allows for their promising applications in catalysis, lithium‐ion batteries, information storage, magnetic cores, ferrofluids, microwave, and medicine. This important review also highlights noteworthy recent developments related to the green synthesis of plant‐mediated magnetic spinel nanoparticles and their fundamental applications.

Effect of nickel substitution on structural and dielectric properties of Mg-Zn based spinel ferrite nanoparticles

Herein, we used sol-gel auto combustion technique for fabrication of the series of nickel substituted magnesium-zinc spinel ferrite (Mg0.3NixZn0.7−xFe2O4) nanoparticles by varying nickel concentrations as 0.00 ≤ x ≤ 0.20. X-ray diffraction (XRD) investigation evidenced that the synthesized nanomaterials are of spinel ferrite nature with secondary phase. Moreover, the crystallite size was observed to be in the range from 13 to 17 nm as estimated by Scherrer’s formula. It has been found that the structural parameters (e.g., bulk density, lattice constant, micro strain, crystallite size, surface area etc) of the as-synthesized magnesium-zinc spinel ferrite nanoparticles have been strongly influenced by doping content of nickel. Moving further, we have investigated the dielectric properties of the prepared nanoparticles in the frequency range from 20 Hz to 20 MHz. The remarkable electric modulus, impedance and dielectric properties of the prepared spinel ferrites made these materials a potential candidate for low- and high-frequency applications.

Effect of praseodymium in cation distribution, and temperature-dependent magnetic response of cobalt spinel ferrite nanoparticles

This work reports cation distribution, magnetic, structural, and morphological studies of rare-earth Pr doped cobalt ferrite nanoparticles CoFe2−x Pr x O4 (x = 0, 0.02, 0.04, 0.06 at%) fabricated by sol-gel auto-combustion method. X-ray diffraction analysis, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and Fourier-transform infrared (FTIR) microscopy were utilized to study the structural and morphological characteristics of the prepared samples. Rietveld refinement by the Material Analyses Using Diffraction (MAUD) software showed the formation of mono-phase cubic spinel structure with Fd-3m space group; however, there was a trace of impure PrFeO3 phase for the sample CoFe1.96Pr0.04O4 (x = 0.06). Cation distribution was inferred from the XRD patterns using MAUD program. FESEM analysis revealed the spherical-shaped particles with dimensions close to the data extracted from XRD analysis and HRTEM images confirmed it. FTIR measurements revealed the presence of two prominent stretching vibrational modes confirming the successful formation of ferrite spinel structure. Magnetic properties of the nanoparticles were measured at two different temperatures 300 K and 10 K. For the low temperature of 10 K a high sensitive measurement method as Superconducting Quantum Interference Device (SQUID) magnetometry was used and Vibrating Sample Magnetometer (VSM) recorded the magnetic data at 300 K. Comparison of the magnetic results exhibited a significant enhancement with temperature drop due to the reduction in thermal fluctuations. Paramagnetic nature of rare-earth ions may be the main reason for M S decrement from 76 emu g−1 (x = 0.0) to 60 emu g−1 (x = 0.02) at 300 K. At 10 K, the estimated cation distribution played a vital role in justification of obtained magnetic results. All the obtained data showed that the synthesized magnetic nanoparticles can be implemented in permanent magnet industry and information storage fields, especially when it comes to lower temperatures.

Structural, dielectric, impedance and electric modulus analysis of Ni substituted copper spinel ferrites nanoparticles for microwave device applications

A series containing five samples of nickel substituted copper spinel ferrite (NixCu1-xFe2O4) nanoparticles with five different nickel concentrations varying as x = 0.00, 0.03, 0.06, 0.09, 0.12, fabricated with the aid of sol-gel auto-combustion technique. Through X-ray diffraction analysis, the structural properties of the compound were determined, which revealed that the prepared nanomaterials possess a spinel nature which was confirmed due to the existence of a secondary phase. The crystallite size was ascertained by applying the Scherrer formula, which was brought up in the range of 8–11 nm. The experimental parameters such as magnetic stirring speed, the molarity of reactants, synthesis temperature, the quantity of citric acid, and annealing were kept controlled. The substitution of nickel in copper spinel ferrite made a significant effect on the structural variables such as crystallite size stacking fault, lattice strain, micro-strain, dislocation density, bulk density, Impedance Analyzer (LCR meter) was used to get the dielectric properties in the frequency extended from 1 Hz to 20 MHz. From the obtained results it was depicted that the synthesized nanomaterials might be able to give response to the electromagnetic radiations, hence these can be usefully applied in microwave devices. Tangent loss and dielectric constant are varied due to Ni2+ content. Impedance loss shows the grain boundaries are dominant as a function of Ni2+ content. Inverse relation of AC frequency with the dielectric constant exposed the existence of Maxwell–Wagner type interfacial polarization. The various dielectric plots give awareness about the conducting grains and resistive grain boundaries that play a vital role in understanding the dielectric relaxation in the material. The ac conductivity is also determined due to Ni2+ content. From the observed electrical parameters, it can be propounded that the prepared nanocrystalline particles hold semiconducting nature and can be employed as a dielectric in low-frequency devices, and might be utilized as a conductor in high-frequency devices.

A mini-review on AFe2O4 (A = Zn, Mg, Mn, Co, Cu, and Ni) nanoparticles: Photocatalytic, magnetic hyperthermia and cytotoxicity study

Spinel ferrite nanoparticles particle size play a vital role in determining the properties of the material and behavior in biomedical applications. Investigators have taken an extraordinary consideration and synthesis of spinel ferrite nanoparticles due to their extensive applications across different fields such as biomedical and industrial fields as compared to bulk counterparts. The present review focuses on the role of nanoparticle size (<100 nm) in different biomedical applications, the reason for such size effect, and the best size necessity for the greatest performance in various biomedical applications, mainly on the spinel ferrite nanoparticle's induction heating (magnetic hyperthermia), photocatalysis, and cytotoxicity properties. In this magnetic hyperthermia, photocatalytic and cytotoxicity study, new chances will be elevated to address the tasks capably and efficiently using modified spinel ferrites. Spinel ferrite nanoparticles are less price magnetic materials and are stable under various circumstances. This review purposes to contribute to the applications of various spinel ferrite nanoparticles in medicine and the environment and their broader research chances across various disciplines. Moreover, the possible retrieval and recycling of ferrite nanoparticles' existence as a catalyst in wastewater treatment are addressed. Overall, this review huts light on the present position of spinel ferrite nanoparticles concerning their biocompatibility properties. In the survey of the literature, fewer articles are existing on the cytotoxicity study of the spinel ferrite nanoparticles.