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Using the example of the mineral magnetite, which is the main component of magnetic volcanic sand, a quantum-chemical analysis of the nature of paramagnetic properties was carried out using the molecular orbital method. Magnetic properties are among the most important characteristics of substances, and magnetic interaction is one of the fundamental forces in the universe. Understanding the chemical nature of magnetic properties allows not only to effectively use materials with magnetic properties, but also to create new materials with the desired characteristics. The magnetic properties of substances depend on their structure and elemental composition, since each charged particle inside the substance has its own magnetic moment-spin. [ABSTRACT FROM AUTHOR]

The core and surface structure, and magnetism of mechano-synthesized LaFeO3 nanoparticles (30–40 nm), Eu3+-doped (La0.70Eu0.30FeO3), and Eu3+/Cr3+ co-doped (La0.70Eu0.30Fe0.95Cr0.05O3) are reported. Doping results in a transition from the O′-type to the O-type distorted structure. Traces of reactants, intermediate phases, and a small amount of Eu2+ ions were detected on the surfaces of the nanoparticles. The nanoparticles consist of antiferromagnetic cores flanked by ferromagnetic shells. The Eu3+ dopant ions enhance the magnetization values relative to those of the pristine nanoparticles and result in magnetic susceptibilities compatible with the presence of Eu3+ van Vleck paramagnetism of spin–orbit coupling constant (λ = 363 cm−1) and a low temperature Curie–Weiss like behavior associated with the minority Eu2+ ions. Anomalous temperature-dependent magnetic hardening due to competing magnetic anisotropy and magnetoelectric coupling effects together with a temperature-dependent dopant-sensitive exchange bias, caused by thermally activated spin reversals at the core of the nanoparticles, were observed. [ABSTRACT FROM AUTHOR]

This study aimed to develop multifunctional nanoplatforms for both cancer imaging and therapy using superparamagnetic iron oxide nanoparticles (SPIONs). Two distinct synthetic methods, reduction–precipitation (MR/P) and co-precipitation at controlled pH (MpH), were explored, including the assessment of the coating's influence, namely dextran and gold, on their magnetic properties. These SPIONs were further functionalized with gadolinium to act as dual T1/T2 contrast agents for magnetic resonance imaging (MRI). Parameters such as size, stability, morphology, and magnetic behavior were evaluated by a detailed characterization analysis. To assess their efficacy in imaging and therapy, relaxivity and hyperthermia experiments were performed, respectively. The results revealed that both synthetic methods lead to SPIONs with similar average size, 9 nm. Mössbauer spectroscopy indicated that samples obtained from MR/P consist of approximately 11–13% of Fe present in magnetite, while samples obtained from MpH have higher contents of 33–45%. Despite coating and functionalization, all samples exhibited superparamagnetic behavior at room temperature. Hyperthermia experiments showed increased SAR values with higher magnetic field intensity and frequency. Moreover, the relaxivity studies suggested potential dual T1/T2 contrast agent capabilities for the coated SPpH-Dx-Au-Gd sample, thus demonstrating its potential in cancer diagnosis. [ABSTRACT FROM AUTHOR]

Herein, the synthesis of Co2Si5N8 nitridosilicate from α‐Ca2Si5N8 by ion exchange is described. The monoclinic Co2Si5N8$\left(\text{Co}\right)_{2} \left(\text{Si}\right)_{5} \left(\text{N}\right)_{8}$ structure (space group Cc) is compared with those of the related nitridosilicates Ca2Si5N8 and Fe2Si5N8 its magnetic properties are profoundly investigated. Most interestingly, polycrystalline Co2Si5N8 exhibits a quasi‐temperature‐independent paramagnetic susceptibility of about 6×10−3 cm3 mol−1$>$$ 6\times {10}^{-3} {\text{cm}}^{3} {\text{mol}}^{-1}$$ over a wide temperature range from 100 to 600 K. Two different magnetic models based on a phenomenological Hamiltonian that takes into account magnetic exchange coupling, crystal‐field interactions, and Zeeman effects within the framework of an angular momentum basis set are refined to the experimental susceptibility datasets. The results of the refinements point to the realization of a pseudo temperature independent paramagnetism for Co2Si5N8 that results from a near‐perfect cancellation of temperature‐dependent contributions to the susceptibility depending delicately on the mixing of ion levels in the electronic states, their relative energies, and the magnetic coupling between them. Additionally, performed direct current field scan, alternating current susceptibility, and heat capacity measurements complete the magnetic characterization and facilitate the identification of impurity phase contributions. [ABSTRACT FROM AUTHOR]

This work presents a comprehensive analysis of the magnetic properties of pristine and citric acid-coated cobalt ferrite (${\rm{CoF}}{{\rm{e}}_{\rm{2}}}{{\rm{O}}_{\rm{4}}}$ CoF e 2 O 4 ) nanoparticles (NPs) dispersed in the host nematic $4{^{\prime}}$ 4 ′ -heptyl-4-biphenylcarbonnitrile (7CB) system. Our results shed light on the promising potential of combining liquid crystals (LC) with magnetic nanoparticles for cancer treatment. This opens up exciting avenues for further exploration and possible applications in the field of oncology. The study focuses on examining the magnetic behaviour of LC dispersed systems with two concentrations of magnetic nanoparticles (0.03 and 0.04 wt%). Notably, intriguing temperature-dependent magnetisation plots reveal a distinctive cusp, which can be attributed to the freezing phenomenon of the liquid crystal. This observation offers valuable insights into the system's magnetic properties and interactions, deepening our understanding of its behavior. [ABSTRACT FROM AUTHOR]

Present work focuses to investigate the impact of rare earth ions (Ce and Gd) on the structural and magnetic properties of nanocrystalline nickel-zinc ferrite. The nanoparticles of Ni0.5Zn0.5Fe2O4, Ni0.5Zn0.5Ce0.02Fe1.98O4, and Ni0.5Zn0.5Gd0.02Fe1.98O4 were synthesized by citric acid–assisted sol–gel method. The formation of cubic spinel structure without additional impurity peaks was confirmed by X-ray diffraction (XRD) pattern. The crystallite size of Ni0.5Zn0.5Fe2O4 (R = 0) and Ni0.5Zn0.5R0.02Fe1.98O4 (R = Ce and Gd) nanoparticles was observed less than ~ 35 nm at sintering temperatures of ~ 300 to ~ 500 ℃. From magnetic measurements, the value of room temperature saturation magnetization of superparamagnetic Ni0.5Zn0.5Fe2O4 (R = 0) was found to be reduced with the doping of Ce and Gd ions from 44.19 ± 0.02 to 39.33 ± 0.03 emu/g and 35.18 ± 0.02 emu/g, respectively, at 300 ℃ and from 60.69 ± 0.04 to 54.11 ± 0.03 emu/g and 55.72 ± 0.04 emu/g, respectively, at 500 ℃. The detailed study of superparamagnetic relaxation in pure and rare earth-doped samples was performed by the thermal magnetization measurements under zero field cool (ZFC) and field cool (FC) processes. Mossbauer spectra revealed the absence of the quadrupole splitting for Ni0.5Zn0.5Ce0.02Fe1.98O4 at tetrahedral (A-site) and octahedral (B-site) sites which indicated cubic symmetry in the crystal structure. Although, the presence of negative asymmetry was observed in Ni0.5Zn0.5Gd0.02Fe1.98O4-doped ferrite sample. Magnetic materials with superparamagnetic properties are desirable in various biomedical applications. [ABSTRACT FROM AUTHOR]

A series of La3+ ion doped magnesium nickel ferrites, Mg 0.5 Ni 0.5 Fe 2-x La x O 4 (0 ≤ x ≤ 0.1) having a cubic spinel structure were prepared by the co-precipitation method. Various characterization techniques, including X-ray diffractometer (XRD), high resolution transmission electron microscopy (HR-TEM), electron spin resonance (ESR) and vibrating sample magnetometer (VSM) were used to investigate structural and magnetic properties. The average crystallite size decreases and lattice parameter increases with La3+ ion doping and lie in the range of 12–7 nm and 8.347–8.361 Å respectively. Analysis of ESR spectra reveals that, g-value with La3+ ion addition decreases from 2.57 to 2.12. The saturation magnetization and the coercivity decrease with increasing rare-earth content. Magnetic-hysteresis (M − H) loop shifts from a ferromagnetic to a superparamagnetic nature with La3+ ion addition. The dielectric study was carried out in the frequency range of 1 KHz to 4000 KHz and temperature ranging 30 °C–350 °C using the impedance analyzer. The dielectric constant decreases with increasing frequency and the La3+ ion concentration. The dielectric loss of the sample increases with increasing temperature. The magnetic properties of the synthesized nanoparticles make them a potential material for stable ferrofluid application and the low tangent loss value makes these material a potential candidate for frequency-based applications. [ABSTRACT FROM AUTHOR]

Artificial glasses containing nanoscale inclusions of iron oxides, including magnetite and hematite, were obtained via the method of the high-temperature melting of rocks. The main factors influencing the magnetic properties of glasses are the composition of the initial charge and the conditions of cooling of the melt. The data of magnetic granulometry and frequency-field dependencies of magnetic susceptibility showed the presence of a sufficiently large superparamagnetic fraction in the samples. Coordinated theoretical modeling using two independent models that take into consideration possible the chemical inhomogeneity of particles and magnetostatic interaction between them made it possible to calculate hysteresis characteristics corresponding to the experiment and to estimate ferrimagnetic concentrations in the samples, including the superparamagnetic fraction. [ABSTRACT FROM AUTHOR]