Spinel Ferrites Research Articles

Optical and magnetic studies of Co0.7Zn0.3Fe2O4 spinel ferrites with Dy3+ substituted for the application of sensors prepared through sol–gel process

Optical and magnetic studies of Co0.7Zn0.3Fe2O4 spinel ferrites with Dy3+ substituted for the application of sensors prepared through sol–gel process

Enhanced magneto-dielectric characteristics of Ni–Cd ferrites/GNPs composites synthesized via sol-gel auto-combustion method

Graphene nanoplatelets (GNPs) and spinel ferrites (SFs) composites enhance their properties and enable multifunctional applications, ranging from electronics to environmental and biomedical fields. This study investigates the Ni0.4Cd0.6Fe2O4/x-GNPs (x = 0 %, 2.5 %, and 5 %) [NCF/0%GNPs, NCF/2.5%GNPs, and NCF/5%GNPs] composites prepared via sol-gel auto combustion (SGAC) synthesis and their enhanced magneto-dielectric characteristics. XRD analysis confirmed the formation of a single-phase spinel matrix of NCF/GNPs composites and observed that the crystallite size (D) was enhanced from 22.8 nm to 33.6 nm with the increasing concentration of GNPs. Moreover, the bandgap energy (Eg) was reduced with the incorporation of GNPs in the NCF sample. The dielectric constant and tangent loss were enhanced with the addition of GNPs in the NCF spinel lattice. The saturation magnetization and microwave operating frequency were reduced from 97.42 emu/g to 55.13 emu/g and 21.49 GHz–11.97 GHz, respectively, while the coercivity was observed to increase from 92.66 Oe to 263 Oe with the incorporation of GNPs in the NCF lattice. The study highlights the potential of NCF/GNPs composites for applications in electronics, energy storage, sensors, and biomedical devices.

Metronidazole adsorption by bio-synthesized silver-zinc ferrite nanoadsorbent in presence of chitosan from aqueous media: response surface methodology

A novel magnetic biocomposite adsorbent, denoted as AgZnFe2O4@Ch, was utilized for the degradation of Metronidazole (MNZ) from water. Various analytical techniques, including vibrating sample magnetometer (VSM), X-ray diffraction (XRD), Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy (FESEM), were applied to investigate the characteristics of the magnetic biocomposite adsorbent. XRD examination confirmed the formation of spinel ferrites phases. FESEM assessment indicated a notable reduction in sample aggregation. The ferromagnetic character of the adsorbent was well demonstrated by VSM analysis. The saturation magnetization value for straightforward separating by the outside magnetic fields was 14.64 emu/g. An analytical modeling approach was used to evaluate and analyze the impacts of factors including MNZ initial concentration, temperature, contact time, adsorbent dosage, and pH. Optimized conditions involved an adsorbent dosage of 0.9 g/L, pH of 7, MNZ initial concentration of 10 mg/L, and a contact time of 50 min, resulting in a peak adsorption efficiency of 65.53% under favorable circumstances. A good degree of fit was achieved with the linear model. The experimental equilibrium data fitting to the Langmuir, Freundlich, and Temkin isotherm models demonstrates that the Langmuir model was an effective and appropriate model for evaluating adsorption. Intraparticle kinetic modeling was also shown to be better suitable for characterizing the MNZ adsorption onto the adsorbent. The thermodynamic analysis indicated that the process of MNZ adsorption by AgZnFe2O4@Ch was characterized by exothermicity and lacked spontaneity.

Influence of synthesis route on structural properties of SnFe2O4 spinel phase via methods of co-precipitation, sol–gel and solvothermal: morphology, phase analysis, crystallite size and lattice strain

In this study, regarding to the wide applications of spinel ferrites in various fields such as Li ion-batteries, photocatalysts, and optoelectronics, the structural and morphological properties of tin ferrite oxide (SnFe2O4) nanoparticles are investigated using X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM). The sol–gel, solvothermal, and co-precipitation methods were used to synthesize the SnFe2O4 nanoparticles, and the effect of annealing temperatures at T = 350 °C, 450 °C, and 550 °C was investigated. The XRD results confirmed the formation of tin ferrite spinel phase at an annealing temperature of 350 °C with a preferred peak (311). Crystallite size (D) and strain (ε) of SnFe2O4 nanoparticles was determined in region 20–45 nm and 2–4 × 10–4, respectively, using the Scherer, Williamson–Hall, and Rietveld computational methods. The results showed that the crystallite size in the samples increased with increasing annealing temperature. This increase is attributed to the reduction of defects, imperfections and lattice strain, which leading to an increase in the lattice constants and unit cell volume in the nanocrystalline structure. The Rietveld method determine smaller crystal sizes compared to the Williamson–Hall and Scherer methods because it can correct for peak broadening by taking into account all instrumental factors. The FESEM images of the synthesized nanostructures of SnFe2O4 showed cubic and polyhedral grains with cluster growth and an average grain size of 50–80 nm. According to the crystal structure of tin ferrite spinel, the cubic morphology confirmed the formation of this structure. The average crystallite size and grains in the synthesized samples was determined using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis, respectively. The formation conditions of the SnFe2O4 spinel phase and other phases in the synthesis process at different temperatures and dependence of structural parameters was studied by various structural models for the samples.

Efficient activation of periodate using MnFe2O4/BC composite for removal of organic contaminants: Performance and mechanism

The periodate (PI)-based advanced oxidation process (AOP) is an economical and energy-saving method for remediating water by degrading pollutants. An efficient system for PI activation was developed by loading manganese ferrite spinel (MnFe2O4) on biochar (BC) through a facile method, affording a metal-oxide MnFe2O4/BC composite catalyst. The developed system demonstrated significant effectiveness in eliminating various organic pollutants, particularly achieving high removal (5.26 and 2.83 times that of biochar and MnFe2O4, respectively) and mineralization (49.7 %) of the model pollutant tetracycline hydrochloride (TC) within 30 min. The system exhibited outstanding catalytic performance under various environmental conditions (pH, inorganic salts, humic acid, and real water bodies), as evidenced by quenching experiments and electron paramagnetic resonance (EPR) studies, proving that superoxide radicals (O2•-) are the main reactive species for TC degradation in the reaction system, in addition to singlet oxygen (1O2), iodyl radicals (IO3•) and hydroxyl radicals (•OH). Potential pathways for TC degradation in this system were revealed based on density functional theory (DFT) and the ecological toxicity of the intermediates was analyzed through quantitative structure–activity relationship (QSAR) assessment. Analysis of the magnetic hysteresis and cycling stability demonstrated that the composites were stable and could be recycled by applying a magnetic field. This work opens a new pathway for designing efficient PI activators for the selective oxidation of organic pollutants and highlights the potential application of this system in practical wastewater treatment.

Ball milling coupled cascade magnetic separation to recover valuable metals from alkali disaggregation copper smelting slags

Due to the lack of effective reduction and recycling methods, copper smelting slags (CSS) containing a large number of valuable metals are stockpiled. This work proposed a novel strategy of ball milling coupled cascade magnetic separation to achieve recovery of magnetite and ferrite and enrichment of Cu and Zn in alkali disaggregation CSS. The Fe grade of recovered magnetite reached as high as 72.43%, and 15.51% of Cu and 16.63% of Zn were recovered efficiently as spinel ferrites. Simultaneously, 70.54% of Cu and 58.18% of Zn were enriched in non-magnetic fraction. Compared with primary magnetic fraction, the grade of Fe in the secondary magnetic fraction increased by 19.19%. Additionally, compared with the control, the recovery efficiency and the grade of Fe in the magnetic products after ball milling increased by 52.11% and 49.20%. The main mechanisms were as follows: (1) The significant dissociation of Fe3O4 from non-magnetic impurities and the transformation of Cu and Zn to ferrite were promoted by ball milling. (2) The separation efficiency of weak magnetic ferrite and Fe3O4 was improved by cascade magnetic separation. Therefore, the proposed strategy could provide a green and sustainable solution for CSS processing.

Study of iron ion distribution in rare earth (La, Pr, Sm, Dy) doped nickel-zinc spinel ferrites through Mössbauer spectroscopy

Ni0.5Zn0.5Fe1.95RE0.05O4 (RE=La, Pr, Sm, Dy) spinel ferrites were prepared using the sol-gel method. X-ray diffraction analyses revealed that doping with rare earth ions increases the lattice parameters of the ferrites, accompanied by a decreasing trend due to lanthanide contraction. Mössbauer spectrum showed that rare earth ion doping facilitates the migration of iron ions from B sites to A sites, with the extent of migration increasing alongside the atomic number of the rare earth elements. Vibrating sample magnetometer tests indicated a general decrease in saturation magnetization following rare earth ion doping. A comprehensive investigation into the effects of different rare earth ion dopings on the properties of Ni-Zn ferrites was conducted by calculating theoretical magnetic moments and comparing them with the experimentally measured values. This comparison elucidated the mechanism behind the magnetic alterations in rare earth-doped spinel ferrites, providing theoretical support for future magnetic modulation in these materials.

The transformation behaviour of ZnFe2O4 spinel particles in the CaO-FexO-SiO2-ZnO slag system

Treating zinc hydrometallurgical residues and other Zn-bearing solid waste in direct lead smelting processes has been recognized as the preferred solution for the sustainable development of the lead and zinc industry. However, new technical problems occurred when changing the starting material of lead-making processes, the pyrometallurgical process for treating zinc hydrometallurgical residues and zinc bearing solid waste usually had the CaO-FexO-SiO2-ZnO slag. Along with the increasing of Zn content in the raw material, high ZnO slag formed, and the ZnFe2O4 spinel particles intended to precipitate from the molten slag. The understanding of the particle behaviour of ZnFe2O4 spinel was the core part of monitoring the slag properties. This study investigated the transformation behaviour of zinc ferrite spinel particles and the changes in glassy slag phase through the high-temperature phase equilibrium experimental technique, and the temperature was 1100 °C-1300 °C and the oxygen potential was 10−8 atm – 10−4 atm. It is found that the particle size of ZnFe2O4 spinel in the molten slag increased along with the increasing of the oxygen potential. The Zn/Fe mass ratio in spinel particles decreased when increasing of temperature and it increased when increasing of oxygen potential. The Fe/SiO2 mass ratio and the Zn content in glassy slag phase gradually increased along with increasing temperature and they decreased along with increasing oxygen potential. The growing and decomposition of ZnFe2O4 spinel was essentially a process of material exchange with the glassy slag phase.

Production of Green energy via Water Splitting mechanism by Mn- doped Cobalt Ferrites [Co1-xMnxFe2O4] based Hydroelectric Cells

In our current study, we have investigated the impact of manganese (Mn) doping on the structural, magnetic properties, and hydroelectric cell properties of cobalt ferrite with chemical formula [Co1-xMnxFe2O4, x=0.00, 0.125]. The solid-state approach has been utilized to synthesize the material. XRDmeasurements revealed the formation of an inverse spinel cubic structure with the space group Fd-3m. FTIR spectra hold a shift in the octahedral and tetrahedral bands with the increase in Mn content in cobalt ferrites. The subsequent rise in ferroelectric behavior has been observed with the net maximum saturation polarization of 1.08μC/cm2. The variation in the permittivity values has been also studied with the increase in Mn content for dry as well as wet hydroelectric cells. The impedance measurements helped us understand the contribution of grains/grain boundaries in the prepared ferrites. The enhanced value of magnetization has been noticed from 48.258 emu/g to 73.089 emu/g upon doping of Mn ions in cobalt ferrite spinel structure lattice.The Mndoped CFO exhibited enhanced performance in hydroelectric cells which demonstrates the great ionic diffusion mechanism with the incorporation of Mn ions. The obtained output makes Mn doped CFO a suitable material for studying microelectronic and hydroelectric cell applications. The purpose of this study is to enhance both ferroelectric as well as ferromagnetic behavior along with the improved value of current in hydroelectric cells.

A novel high-entropy spinel ferrites (CoNiCuZnMg)Fe2O4 catalyst for H2 production via steam reforming of derived volatiles from polypropylene and waste cooking oil

Municipal organic waste conversion to high-value products is a vital carbon–neutral way to simultaneously tackle the energy crisis and environmental contamination. This study aims to develop and evaluate a novel high-entropy spinel ferrites (Co0.2Ni0.2Cu0.2Zn0.2Mg0.2)Fe2O4 catalyst (HEO) toward H2 production from co-pyrolysis volatiles of polypropylene (PP) and waste cooking oil (WCO) in an integrated two-stage reactor system. In the 1st stage of medium temperature reforming, the optimal 3:7 PP/WCO blend mass ratio facilitated H2 production. Under a catalytic reforming at high temperature of 750 °C in the 2nd stage, the HEO catalyst demonstrated remarkable efficiency, yielding 58.43 mmol·g−1 of H2 with a composition of 65.17 %, a notable 22.3 times higher than that without HEO. The catalyst exhibited a prolonged service life of 540 min without compromising H2 selectivity, maintaining a high yield of 510.2 mmol·gcat.−1·s−1. The exceptional performance of HEO arises from the synergistic effects of multiple elements, augments oxygen vacancy, enhances reducibility, and promotes structural stability in the high-entropy system, which causes the strong C–C breaking ability and the excellent C–H breaking abilities of Fe, Ni, Co, Cu, and Zn species. The analysis of tar, gaseous products, and deactivated HEO catalyst characterization results provides a comprehensive understanding of the co-pyrolysis route and volatiles catalytic reforming process. This study developed a high-entropy ferrite catalyst that not only achieves efficient and stable H2 production but also lays the foundation for a new high-entropy catalyst design concept, fostering the development of efficient reforming catalysts for H2 production.

Synthesis of as-prepared and sintered spinel ferrites containing cadmium, copper, and chromium expecting magnetism and photoluminescence

Expecting the dual properties of light emission and magnetism, we synthesized spinel ferrites containing cadmium, copper, and chromium, i.e., Cd0.5Cu0.5CrxFe2-xO4, where x = 0.0, 0.05, 0.1, 0.2, 0.4, and 0.8. The as-prepared materials were synthesized using a coprecipitation method and then sintered to modify their physical and magnetic properties. All the developed materials exhibited stable photoluminescence (PL) emission in the visible range. Vibrating sample magnetometry (VSM) showed negligible coercivity for both the as-prepared and sintered samples, indicating their superparamagnetic properties. Saturation magnetization (Ms) is an index used to realize a strong magnetic force on a material. Ms can be tuned by changing Cr in the spinel ferrites. For the as-prepared material, as Cr increased from x = 0.2 to 0.4, the Ms changed from a higher value to zero/smaller values, while for the sintering material, as Cr increased from x = 0.4 to 0.8, Ms changed from a higher value to nearly zero / smaller values.

The Chemistry of Spinel Ferrite Nanoparticle Nucleation, Crystallization, and Growth.

The nucleation, crystallization, and growth mechanisms of MnFe2O4, CoFe2O4, NiFe2O4, and ZnFe2O4 nanocrystallites prepared from coprecipitated transition metal (TM) hydroxide precursors treated at sub-, near-, and supercritical hydrothermal conditions have been studied by in situ X-ray total scattering (TS) with pair distribution function (PDF) analysis, and in situ synchrotron powder X-ray diffraction (PXRD) with Rietveld analysis. The in situ TS experiments were carried out on 0.6 M TM hydroxide precursors prepared from aqueous metal chloride solutions using 24.5% NH4OH as the precipitating base. The PDF analysis reveals equivalent nucleation processes for the four spinel ferrite compounds under the studied hydrothermal conditions, where the TMs form edge-sharing octahedrally coordinated hydroxide units (monomers/dimers and in some cases trimers) in the aqueous precursor, which upon hydrothermal treatment nucleate through linking by tetrahedrally coordinated TMs. The in situ PXRD experiments were carried out on 1.2 M TM hydroxide precursors prepared from aqueous metal nitrate solutions using 16 M NaOH as the precipitating base. The crystallization and growth of the nanocrystallites were found to progress via different processes depending on the specific TMs and synthesis temperatures. The PXRD data show that MnFe2O4 and CoFe2O4 nanocrystallites rapidly grow (typically <1 min) to equilibrium sizes of 20-25 nm and 10-12 nm, respectively, regardless of applied temperature in the 170-420 °C range, indicating limited possibility of targeted size control. However, varying the reaction time (0-30 min) and temperature (150-400 °C) allows different sizes to be obtained for NiFe2O4 (3-30 nm) and ZnFe2O4 (3-12 nm) nanocrystallites. The mechanisms controlling the crystallization and growth (nucleation, growth by diffusion, Ostwald ripening, etc.) were examined by qualitative analysis of the evolution in refined scale factor (proportional to extent of crystallization) and mean crystallite volume (proportional to extent of growth). Interestingly, lower kinetic barriers are observed for the formation of the mixed spinels (MnFe2O4 and CoFe2O4) compared to the inverse (NiFe2O4) and normal (ZnFe2O4) spinel structured compounds, suggesting that the energy barrier for formation may be lowered when the TMs have no site preference.

Cr dopant regulating d-orbital electronic configuration of NiFe spinel oxide to improve oxygen evolution reaction in Zn-air battery

Significant advancements towards enhancing the catalytic activity of spinel ferrites in oxygen evolution reaction (OER) have been achieved, however, further studies are required on this regard. In this study, Cr-doped spinel ferrite (NiFe2O4) embedded in N-doped C (Cr-NiFe2O4@NC) was synthesized via a high-temperature treatment using an NiFe Prussian blue analog as a precursor and K2Cr2O7 as a Cr source. Owing to the strong octahedral site preference energy, Cr3+ ions were successfully doped into octahedral sites and tailored the electronic configuration of NiFe2O4, as confirmed by XPS. The Cr-substituted Cr-NiFe2O4@NC exhibited the overpotential of 241 mV at 10 mA cm−2, which was smaller than that of NiFe2O4@NC (266 mV) at the same current density. Meanwhile, the Tafel slope of Cr-NiFe2O4@NC (65.32 mV dec−1) was also lower than that of NiFe2O4@NC (86.96 mV dec−1). Therefore, the Cr substitution can improve the electrocatalytic OER performance of NiFe2O4@NC. In particular, an assembled rechargeable Zn-air battery using Cr-NiFe2O4@NC as the cathode catalyst afforded a high power density (61.1 mA cm−2) together with a high specific capacity (740 mA g−1). Amazingly, it could power light-emitting diodes, demonstrating its real-world application. Density functional theory calculations revealed that Cr ion doping led to electron transfer in NiFe2O4, resulting in a density of electronic states close to the Fermi level, which probably regulated the adsorption/desorption behaviors of oxygenate intermediates (*O and *OOH), thus promoting the reaction kinetics of the OER. This study provides a helpful basis for the development of spinel oxides with high electrocatalytic OER activity and durability via cation doping.

Sm3+ doping-adjusted mechanical, dielectric, and radiation shielding properties of cobalt copper nanoferrites

The scarcity of research on the shielding properties of spinel ferrites underscores the necessity for more rigorous investigations. Consequently, this study introduces a facile synthesis method for Co, Cu, and Sm spinel nanoferrites (referred to as CCS nanoferrites) using the citrate combustion technique. The investigation focuses on their mechanical, dielectric, and gamma-ray shielding parameters. Gamma-ray shielding features are obtained theoretically via the Phy-X database. The particle size, nature, and distribution of the present CCS nanoferrites were analyzed using HR-TEM microscopy. HR-TEM results reveal both the spherical shapes and the aggregation of nanoparticles. These observations can be attributed to the interplay of high surface energy and magnetic interactions among the components of the CCS nanoferrites. The Co0.5Cu0.5Sm0.15Fe1.85O4 nanoferrite exhibits an optimal dielectric constant value of 4587, with an enhanced ratio of 1618% compared to the pristine CCS0 sample. Additionally, it demonstrates an optimal conductivity of 38.59 μ (Ω·m)−1, with an enhanced ratio of 1105%. Furthermore, the loss is reduced to 2.65, showing an improvement ratio of 54% compared to the pristine nanoferrite at room temperature and 50 Hz. Moreover, the longitudinal modulus, shear modulus, Young's modulus, and bulk modulus of the nanoferrite Co0.5Cu0.5Sm0.15Fe1.85O4 were increased from 1.79 to 4.96 GPa, 0.32–0.93 GPa, 0.88–2.56 GPa, and 1.37–3.73 GPa, respectively, when compared to the pristine sample. The comparative study of half-value layers at 0.662 MeV revealed that CCS nanoferrites exhibit smaller half-value layers than common radiation shielding materials. Additionally, the study highlighted the enhanced radiation shielding performance of the nanoferrites. Concerning the dielectric, mechanical, and ionizing radiation shielding properties of the CCS spinel nanoferrites, the CCS5 (with the highest Sm content) has the optimum ionizing radiation shielding ability with the highest dielectric and mechanical parameters compared to the other samples. The implications of these findings extend to potential applications in biomedicine, radiation protection, and the optimization of electronic devices operating in radiation fields.

ZnxFe3-xO4–ZnO heterojunction interfaced with poly(L-DOPA) electron transfer mediator layer for enhanced visible light photocatalytic activity

Z-scheme heterojunctions comprising ZnxFe3-xO4@poly(L-DOPA)@ZnO (ZF@PD@ZnO) were synthesized using solvothermal and precipitation techniques. The study aimed to investigate the impact of the poly(L-DOPA) electron transfer mediator on the photocatalytic performance of ZnxFe3-xO4@ZnO (ZF@ZnO) nanocomposites under visible light irradiation. X-ray diffraction (XRD) and HRTEM analysis confirmed the formation of heterostructures, identifying the crystalline phases of both ZnO and zinc ferrite. BFTEM images revealed a polyhedral shape for all samples, with a tendency toward mild agglomeration. The partial inversion of the zinc ferrite cubic spinel structure was evidenced by FT-IR, XPS, and VSM analyses. Zinc ferrite was found to be ferromagnetic, with cation distributions between tetrahedral (A) and octahedral (B) positions as [Zn0.62+Fe0.43+]A[Fe0.42+Fe1.63+]BO4. The samples exhibited notable photocatalytic activity against Rhodamine B, serving as a model contaminant. Furthermore, the stability and reusability of the samples were examined. Additionally, the study elucidated the photocatalytic mechanism produced by the ternary Z-scheme ZF@PD@ZnO, involving spin-polarized charge carriers. Energy band alignment was evaluated by combining ultraviolet photoelectron spectroscopy (UPS) with UV-Vis spectroscopy. The interplay between band alignment and reactive oxygen species (ROS) generation was discussed in correlation with EPR results. Enhanced ROS generation under visible light illumination, observed in the ZF@PD@ZnO nanocomposite, is mainly due to the addition of the conductive poly(L-DOPA) layer, acting as an electron transfer mediator in the Z-scheme heterojunction, ensuring enhanced charge separation.

Crystal structure and peculiarities of microwave parameters of Mg1-xZnxFe2O4 nanospinel ferrites

Employing an advanced citrate precursor methodology, we successfully synthesized nanoscale spinel ferrites, denoted as Mg1-xZnxFe2O4 (where x ranges between 0.0 and 1.0) or MZFO. Comprehensive analysis, utilizing state-of-the-art X-ray diffraction (XRD) techniques, demonstrated the defining attributes of the crystal structure. All examined specimens consistently exhibited a singular phase, adopting a cubic crystalline architecture. XRD pattern analysis allowed us to deduce the average particle dimensions of these ferrite specimens, which span between 17.2 nm and 31.5 nm. This observed size distribution corroborates well with transmission electron microscopy (TEM) imagery estimations. Delving into the Fourier-transform infrared (FTIR) spectra, two distinctive absorption bands of ferrites emerged: the first between 540 and 570 cm−1 and the subsequent between 339 and 435 cm−1. To glean insight into the electromagnetic attributes of MZFO, we meticulously assessed the experimentally ascertained S-parameters. This scrutiny spanned a frequency spectrum of 8–18 GHz. It was inferred that electromagnetic wave energy dissipation arises chiefly from a combination of electrical and magnetic phenomena. The underlying mechanisms of electrical dissipation can be attributed to polarization processes. Concurrently, the magnetic energy losses predominantly stem from magnetization reversal dynamics. Notably, a substantial attenuation observed in the reflected wave energy, ranging between −10 and −18.5 dB, augments the potential for this material's integration into practical applications.

Sm Doped Cu–Ni Spinel Ferrite Nanoparticles for Hyperthermia and Photocatalytic Applications

Sm Doped Cu–Ni Spinel Ferrite Nanoparticles for Hyperthermia and Photocatalytic Applications

Mechanical and thermal response of XFe2O4 (X = Zn, Ag and Co) spinel ferrites via IR-spectroscopy and first-principles calculations

The lack of comprehensive literature on the all-important aspect of the elasticity of spinel ferrites led to the hydrothermal synthesis of different (Co, Zn, Ag) spinel ferrites. IR spectroscopy revealed the characteristic absorption bands of metal-oxygen in all three compositions. The shifting of tetrahedral and octahedral bending vibrations towards higher frequencies owes to changes in inter-atomic and inter-ionic distances. Elastic parameters, wave velocities, and Debye temperature have been calculated using IR spectroscopy data. Elastic parameters have been higher for Co ferrites than Zn and Ag ferrites. The Poisson ratio seems to be consistent for different spinel ferrites. Shear wave velocity has been found to be higher than longitudinal wave velocity because perpendicular particle vibrations take higher energy than parallel vibrations. Wave velocities have been found to be higher in Ag ferrites than in the other two compositions. Debye temperature follows the same trend as elastic parameters. Additionally, we have confirmed the mechanical stability of the Co, Zn, and Ag ferrites using the first-principles calculations in the density functional theory (DFT) approach framework. Interestingly, the Co/Zn/Ag ferrites exhibit semiconducting nature with a band gap of 3.96/3.66/0.71 ev. Our study could pave the way for next-generation spintronic devices.

Nitric oxide nano-reactor DNMF/PLGA enables tumor vascular microenvironment and chemo-hyperthermia synergetic therapy

BackgroundBreast cancer ranks first among malignant tumors, of which triple-negative breast cancer (TNBC) is characterized by its highly invasive behavior and the worst prognosis. Timely diagnosis and precise treatment of TNBC are substantially challenging. Abnormal tumor vessels play a crucial role in TNBC progression and treatment. Nitric oxide (NO) regulates angiogenesis and maintains vascular homeostasis, while effective NO delivery can normalize the tumor vasculature. Accordingly, we have proposed here a tumor vascular microenvironment remodeling strategy based on NO-induced vessel normalization and extracellular matrix collagen degradation with multimodality imaging-guided nanoparticles against TNBC called DNMF/PLGA.ResultsNanoparticles were synthesized using a chemotherapeutic agent doxorubicin (DOX), a NO donor L-arginine (L-Arg), ultrasmall spinel ferrites (MnFe2O4), and a poly (lactic-co-glycolic acid) (PLGA) shell. Nanoparticle distribution in the tumor was accurately monitored in real-time through highly enhanced magnetic resonance imaging and photoacoustic imaging. Near-infrared irradiation of tumor cells revealed that MnFe2O4 catalyzes the production of a large amount of reactive oxygen species (ROS) from H2O2, resulting in a cascade catalysis of L-Arg to trigger NO production in the presence of ROS. In addition, DOX activates niacinamide adenine dinucleotide phosphate oxidase to generate and supply H2O2. The generated NO improves the vascular endothelial cell integrity and pericellular contractility to promote vessel normalization and induces the activation of endogenous matrix metalloproteinases (mainly MMP-1 and MMP-2) so as to promote extravascular collagen degradation, thereby providing an auxiliary mechanism for efficient nanoparticle delivery and DOX penetration. Moreover, the chemotherapeutic effect of DOX and the photothermal effect of MnFe2O4 served as a chemo-hyperthermia synergistic therapy against TNBC.ConclusionThe two therapeutic mechanisms, along with an auxiliary mechanism, were perfectly combined to enhance the therapeutic effects. Briefly, multimodality image-guided nanoparticles provide a reliable strategy for the potential application in the fight against TNBC.Graphical

Effects of thermal, stress, and electric fields on microstructure and ion distribution of (Mg0.1Mn0.1Co0.1Ni0.2Ti0.1Cu0.1Zn0.2)Fe2.1O4 spinel ferrites

In this work, conventional sintering, hot-pressing sintering, and spark plasma sintering techniques were utilized to simulate the thermal field, thermal-stress field, and thermal-stress-electric field, respectively. The effects of these fields on the microstructure and cation distribution of the (Mg0.1Mn0.1Co0.1Ni0.2Ti0.1Cu0.1Zn0.2)Fe2.1O4 ferrite (HEF) material were comprehensively analyzed. The results indicate that in the temperature range of 1000–1100 °C, the thermal field provides the driving force for sintering, promotes grain growth (average particle size: 2→7 μm), and increases crystallinity degree. The stress field brings the particles into close contact with each other, facilitates diffusion, and delays grain growth (0.5→5 μm). The electric field reduces grain boundary energy, causes mass transfer, and makes the grains finer (0.5→0.7 μm) and more uniform. Mathematical model analysis reveals that the thermal field is beneficial to the random distribution of cations, which yields an inversion degree (γ) of about 2/3 and increases the configuration entropy of HEF. The stress field leads to lattice distortion, permits ions with larger radius to occupy tetrahedral positions, and changes the cell parameters and oxygen position parameter of HEF. Finally, the interaction between electric field and crystal charges increases the electrostatic field energy, which promotes the formation of positive spinel structure and maximizes the crystal field stability energy. X-ray photoelectron spectra, Raman spectra, and change in lattice constant confirm the rationality of the mathematical model, and can be used to establish the model of the crystal structure under field effects.