Magnetic Glass Research Articles

Synthesis of Ferrocene‐Containing Schiff Bases Based on 3‐Aminopropyltriethoxysilane Oligomers for Covalent Modification of Glass Surfaces and Creation of Soft Magnetic Materials

ABSTRACTA ferrocene‐containing oligoorganosiloxane with a number‐average degree of polymerization of 8.8 and a number‐average molecular weight of 3200 is synthesized by hydrolytic condensation of 3‐aminopropyltriethoxysilane followed by chemical modification of the resulting oligomer with acetylferrocene. Its structure is characterized by MALDI‐TOF, NMR and IR spectroscopy. 1H NMR spectroscopy shows the predominance of more thermodynamically stable units containing anti‐configuration Schiff bases. Using IR spectroscopy as well as experimental determination of surface energy and its polar (acid–base) and dispersion components, the covalent immobilization of ferrocene‐containing oligoorganosiloxane on a glass surface after heating at 110°C is shown. The formed coating provides hydrophobization, acid–base indifference of the glass surface and serves as a precursor for the formation of magnetically soft materials after pyrolysis in argon already at 350°C. The main stages of ferrocene‐containing oligoorganosiloxane thermal destruction in an inert atmosphere and the formation of a mixture of iron and silicon oxides during its thermal oxidative destruction are established by combination of TGA/DTA, IR spectroscopy and elemental analysis. The proposed approach opens up new possibilities for functionalizing silicates surfaces, creating magnetic glasses, as well as regulating surface energy and its components.

Stepwise Assembly of DNA Nanostructures in a Surface-Based Method.

Hierarchical assembly of DNA nanostructures has already led to superstructures of ever-increasing level of complexity. Processing control in building nanostructures hierarchically is desirable but remains underexplored. Here, we present the stepwise assembly of DNA origami nanostructures by a surface-based method. With solid support of magnetic beads or glass slides, we demonstrate hierarchical assembly of preformed DNA origami units to a number of superstructures. The anchoring of DNA constructs on the surface results in better programmability and controllability for DNA self-assembly, suggesting a potential for our surface-based strategy to become a general and standardized assembly methodology of DNA nanostructures and beyond.

Cluster spin glass behaviour of Co2+−Al3+ layered double hydroxides

Frequency-dependent magnetic behaviour of cobalt-aluminium layered double hydroxides (LDH) with the Co/Al ratio of 2 and 3, was studied between 2 and 300 K. It was found from analysis of the temperature-dependent ac magnetic susceptibility that these LDH exhibit a magnetic cluster spin glass behaviour regardless of their basal spacing value and the Co/Al ratio as evidenced by EA/kBT0 > 1 relation obtained using Vogel-Fulcher law. The obtained values of Mydosh parameters in the range of 0.017–0.052 suggest that some of these materials are not far from the canonical spin glasses, implying a rather small size of the magnetic clusters.

Determination of the Optimum Architecture of Additively Manufactured Magnetic Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug-Delivery Applications.

For better bone regeneration, precise control over the architecture of the scaffolds is necessary. Because the shape of the pore may affect the bone regeneration, therefore, additive manufacturing has been used in this study to fabricate magnetic bioactive glass (MBG) scaffolds with three different architectures, namely, grid, gyroid, and Schwarz D surface with 15 × 15 × 15 mm3 dimensions and 70% porosity. These scaffolds have been fabricated using an in-house-developed material-extrusion-based additive manufacturing system. The composition of bioactive glass was selected as 45% SiO2, 20% Na2O, 23% CaO, 6% P2O5, 2.5% B2O3, 1% ZnO, 2% MgO, and 0.5% CaF2 (wt %), and additionally 0.4 wt % of iron carbide nanoparticles were incorporated. Afterward, MBG powder was mixed with a 25% (w/v) Pluronic F-127 solution to prepare a slurry for fabricating scaffolds at 23% relative humidity. The morphological characterization using microcomputed tomography revealed the appropriate pore size distribution and interconnectivity of the scaffolds. The compressive strengths of the fabricated grid, gyroid, and Schwarz D scaffolds were found to be 14.01 ± 1.01, 10.78 ± 1.5, and 12.57 ± 1.2 MPa, respectively. The in vitro study was done by immersing the MBG scaffolds in simulated body fluid for 1, 3, 7, and 14 days. Darcy's law, which describes the flow through porous media, was used to evaluate the permeability of the scaffolds. Furthermore, an anticancer drug (Mitomycin C) was loaded onto these scaffolds, wherein these scaffolds depicted good release behavior. Overall, gyroid-structured scaffolds were found to be the most suitable among the three scaffolds considered in this study for bone tissue engineering and drug-delivery applications.

High magnetic susceptibility-based vanadate tellurite glasses for magneto-optical device applications

Tellurite glasses modified with V2O5, Fe2O3, and Na2O (TVFN), along with Sm3+-doped Gd2O3 and Sb2O3 based tellurite (TVGSNSm) glasses evaluated for various properties. The thermal stability of these glasses, with a critical value of 105 °C advantageous to luminescence. Fourier transform infrared and micro-Raman bands were identified at 669, 745, 859, 943, and 1003 cm−1 in the deconvolution. Electron spin resonance revealed a signal at a magnetic field of 340.75 mT (g = 1.77). The magnetic hysteresis of TVFN glasses from a vibrating sample magnetometer which possess coercivity 62 mT and remanence 1.5х10−2 Am2/kg with a saturation magnetization 0.1975 A m2/kg and magnetic susceptibility as high as 0.1328. The magnetic nature confirmed by superconducting quantum interference device. Photoluminescence of Sm3+-doped TVGSNSm glasses excited by 408 nm showed 646 nm (red-orange) dominated emission band over the 603 nm band. These findings underscore the potential of TVFN glasses for applications in magneto-optical devices.

Planar XY magnetic glass state in the Gd2ScNbO7 pyrochlore

Here a spin glass system with emergent planar ordered spin clusters is investigated. The mixed B-site pyrochlore Gd2ScNbO7has been synthesized and characterized through a variety of techniques, including x-ray diffraction, magnetic susceptibility, muon spin relaxation, heat capacity and neutron scattering. Despite a Curie-Weiss temperature of -3.93(3) K, indicating net antiferromagnetic interactions, no signs of long ranged magnetic ordering are found down toT= 0.3 K. Instead, a disordered magnetic state emerges with a small correlation length of 2.1(1) Å of single tetrahedra. A Reverse Monte Carlo analysis of the polarized neutron scattering data reveals short-range antiferromagnetic order with emergent XY spin ordering similar to the parent pyrochlore compounds. Muon spin relaxation, and AC susceptibility measurements confirm that the magnetization condenses into a glass, with 10 % of the potential entropy missing in the specific heat. This magnetic ground state is similar to what is observed in Gd2Sn2O7just above the ordering temperature, without the eventual long-range ordering at low temperature.

Increasing Light-Induced Forces with Magnetic Photonic Glasses

In this work, we theoretically and experimentally study the induction of electromagnetic forces in an opal-based magnetic photonic glass, where light normally impinges onto a disordered arrangement of SiO2 spheres by the aggregation of Fe3O4 nanoparticles. The working wavelength is 633 nm. Experimental evidence is presented for the force that results from forced oscillations of the photonic structure. Finite-element method simulations and a theoretical model estimate the magnetic force volumetric density value, peak displacement, and velocity of oscillations. The magnetic force is of the order of 56 microN, which is approximately 500-times higher than forces induced in dielectric optomechanical photonic crystal cavities.

Microstructure and properties of YIG/YIG magnetic homogenization joint fabricated by a novel Bi2O3–B2O3–NiO–Fe2O3 magnetic glass

Aiming at mechanical and electromagnetic demands for yttrium iron garnet ferrite (YIG) integrated structure, a novel Bi2O3–B2O3–NiO–Fe2O3 (BBNF) low-melting magnetic glass braze was designed. Nearly magnetic homogenization YIG/YIG joints were fabricated successfully. In-situ magnetic microcrystalline phases NiFe2O4 and Ni2FeO4 with good mechanical property precipitated in the brazing seam. The magnetization performance of YIG/YIG joints was significantly promoted. Merely 10 % difference of the magnetization strength per unit mass of the joints to YIG base materials was achieved. The joint shear strength reached its maximum of 79 MPa due to the enhancement of the microcrystalline phases. It is significant for improving both structural stability and functional reliability of the microwave devices for long-term service.

The scandium effect in Gd-rich BMGs: How and why does this ingredient work better than others?

Scandium is commonly known as a superior modifier for most alloys and compounds, substantially improving their phase stability and physical properties, as well as glass-forming ability. A special case is rare-earth based magnetic metallic glasses, which are an unique platform for intra-elemental substitution due to the chemical affinity of the lanthanides, yttrium and scandium. The latter, used as an alloying additive and being the smallest atom among the entire family, can drastically affect structure formation and magnetism in these metallic glasses. The main issue is that its modifying role is not well understood due to scarce information on the scandium effects in such rare-earth systems. This study is focused on thermal and magnetic analysis of some popular Gd-based BMGs redesigned with minor Sc additives. Here, we consider temperature behavior of specific heat capacity and entropy functions for both amorphous and crystalline phases to estimate the scandium effect on GFA and thermal stability of the glasses. As well, we inspect magnetic and magnetocaloric properties of these BMGs to understand whether this very expensive metal can radically improve the alloy magnetism and make these materials suitable for potential applications.

The role of Cr in optimizing properties of Fe–B–C–P–Si–Mo–Cr metallic glasses for applications

With the rapid development of third-generation semiconductors, there is an urgent need to develop high-performance soft magnetic Fe-based metallic glasses tailored particularly for their high-frequency applications. In this work, new Fe76−yB7C7P7Si3Moy−xCrx (y = 0, 1, 2, 3 at.%, x ≤ y) alloys with relatively high glass-forming ability (GFA) were developed. The effects of replacing Mo with Cr on GFA, thermodynamic properties, soft magnetic properties, electrical resistivity (ρ), and corrosion resistance at different Fe contents were systematically studied. The possible causes of GFA variation were discussed. The results show that the addition of a small amount of Cr replacing Mo under different Fe contents would not lead to a decrease in GFA. The critical sizes of Cr-containing glassy alloys are 1–2.5 mm. These alloys possess relatively high saturation magnetization (Ms) of 1.29–1.41 T and lower coercivity (Hc) of 0.7–1.8 A/m, contributing to the reduction of hysteresis loss. In addition, Cr increases ρ of the alloys, reaching up to 162 μΩ cm, which is beneficial to reducing eddy current loss at high frequency. Furthermore, Cr effectively enhances corrosion resistance, thereby increasing the service life of the alloys in harsh environments. The role of Cr in these aspects makes it a beneficial element in soft magnetic metallic glasses for high-frequency applications.

Relating laser powder bed fusion process parameters to (micro)structure and to soft magnetic behaviour in a Fe-based bulk metallic glass

This work aims to establish fundamental processing-(micro)structure-property links in a commercial Fe-based Kuamet6B2 bulk metallic glass (BMG) processed by laser powder bed fusion (LPBF). With that purpose, amorphous powders were processed using a pulsed-wave system and a simple meander strategy. The laser power, the scan speed, and the hatch distance were varied over wide intervals within the conduction regime. The processability window leading to samples with good dimensional accuracy and mechanical stability was determined. Within this window, the manufactured samples were crystalline/amorphous composites and the crystalline regions were formed by equiaxed ultrafine and nanograins with random orientations. Processing parameters yielding the densest prints caused severe crystallization while, conversely, parameter sets allowing the material to retain a high amorphous fraction led to significant lack-of-fusion defects and residual cracking along directions perpendicular to crystalline/amorphous interfaces. Comparatively, for a fixed hatch distance, the scanning speed had a stronger effect than the laser power in the resulting amorphous fraction due to its stronger influence on the melt pool size and, in turn, on the corresponding HAZ volume. The saturation magnetization and the coercive field were inversely related to the amorphous fraction. This work allows to derive fundamental guidelines for the successful additive manufacturing of soft magnetic Fe-based bulk metallic glasses (BMGs) by laser powder bed fusion (LPBF).

Folic acid-enhanced magnetic mesoporous bioactive glass against infections in targeted tumor therapy with tetracycline precision loading

Cancer remains one of the most serious diseases worldwide, capable of affecting any organ or tissue, including bones. Current treatment for bone cancer typically involves surgical removal of the cancerous tissue from the bones, with the resulting cavity filled using bone substitute materials. However, surgery can only remove most of the cancerous tissue, necessitating continued treatment and post-operative follow-up. Additionally, there is a risk of bacterial infection during the surgical procedure. Even if the surgery is successful, bacterial infection during or after the operation can still occur, making infection prevention a crucial aspect of the procedure.This research is primarily divided into four parts. Firstly, iron nanoparticles are coated onto mesoporous bioactive glass (MBG) to impart the material with characteristics suitable for magnetothermal therapy, chemodynamic therapy, and magnetic resonance imaging (MRI). The second part involves the modification of thiol groups (-SH) and the anticancer drug camptothecin (CPT) to enable controlled drug release for cancer cell eradication. In the third part, folic acid (FA) is introduced to the material's surface for cancer cell targeting. Finally, tetracycline (TC) is loaded into the material's cavities, providing continuous release in the affected area after surgery to prevent bacterial infections.

Magnetic field-induced narrow first-order and metamagnetic phase transitions of Nd5Ge3

We report on the magnetic behaviour of Nd5Ge3 by investigating through magnetization, neutron diffraction and muon spin relaxation measurements. Temperature dependent-magnetization, muon depolarization rate (λ), initial asymmetry (A0) and the stretched exponent (β) show a clear anomaly at the Néel temperature TN ∼ 54 K. However, the short-range correlated ferromagnetic interactions below TN are inferred from the diffuse scattering mechanism as revealed by zero-field neutron diffraction data. Narrow first order phase transition is due to the competing interaction of a high temperature weak-antiferromagnetic and low temperature glassy states. Magnetic field-induced reentrant spin glass state from a magnetic glass state is observed, before it transforms to a ferromagnetic state.

Additive Manufacturing of Iron Carbide Incorporated Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug Delivery Applications.

In this study, we have synthesized a bioactive glass with composition 45SiO2-20Na2O-23CaO-6P2O5-2.5B2O3-1ZnO-2MgO-0.5CaF2 (wt %). Further, it has been incorporated with 0.4 wt % iron carbide nanoparticles to prepare magnetic bioactive glass (MBG) with good heat generation capability for potential applications in magnetic field-assisted hyperthermia. The MBG scaffolds have been fabricated using extrusion-based additive manufacturing by mixing MBG powder with 25% Pluronic F-127 solution as the binder. The saturation magnetization of iron carbide nanoparticles in the bioactive glass matrix has been found to be 80 emu/g. The morphological analysis (pore size distribution, porosity, open pore network modeling, tortuosity, and pore interconnectivity) was done using an in-house developed methodology that revealed the suitability of the scaffolds for bone tissue engineering. The compressive strength (14.3 ± 1.6 MPa) of the MBG scaffold was within the range of trabecular bone. The in vitro test using simulated body fluid (SBF) showed the formation of apatite indicating the bioactive nature of scaffolds. Further, the drug delivery behaviors of uncoated and polycaprolactone (PCL) coated MBG scaffolds have been evaluated by loading an anticancer drug (Mitomycin C) onto the scaffolds. While the uncoated scaffold demonstrated the drug's burst release for the initial 80 h, the PCL-coated scaffold showed the gradual release of the drug. These results demonstrate the potential of the proposed MBG for bone tissue engineering and drug delivery applications.

An intrinsic connection between the liquid-liquid transition and fragile-to-strong transition in soft magnetic Fe-based metallic glasses: Comparisons with other metallic glasses

There are two significant abnormal transitions observed in metallic glass forming liquids (MGFLs), i.e., liquid-liquid transition (LLT) above liquidus temperature and fragile-to-strong (F-S) transition in supercooled region. In this study, we focus on the correlation between LLT and F-S transition in Fe-based soft magnetic metallic glasses (MGs) for the first time. We find that the more distinct the LLT is, the weaker is the F-S transition, and the smaller is the glass forming ability (GFA). By employing molecular dynamics simulation, we identify that this relationship is due to the inherent correlated evolution trends of crystal-like clusters between the LLT and the F-S transition regions. Moreover, we analyze a general rule regarding the LLT and F-S transition in MGs, along with their composition-dependent peculiarities. This work sheds light on the process of liquid-solid inheritance of different MGs, and deepens the understanding of the liquid dynamics of MGs and their following GFA.

Chitosan/MWCNTs nanocomposite coating on 3D printed scaffold of poly 3-hydroxybutyrate/magnetic mesoporous bioactive glass: A new approach for bone regeneration

The utilization of 3D printing has become increasingly common in the construction of composite scaffolds. In this study, magnetic mesoporous bioactive glass (MMBG) was incorporated into polyhydroxybutyrate (PHB) to construct extrusion-based 3D printed scaffold. After fabrication of the PHB/MMBG composite scaffolds, they were coated with chitosan (Cs) and chitosan/multi-walled carbon nanotubes (Cs/MWCNTs) solutions utilizing deep coating method. FTIR was conducted to confirm the presence of Cs and MWCNTs on the scaffolds' surface. The findings of mechanical analysis illustrated that presence of Cs/MWCNTs on the composite scaffolds increases compressive young modulus significantly, from 16.5 to 42.2 MPa. According to hydrophilicity evaluation, not only MMBG led to decrease the contact angle of pure PHB but also scaffolds surface modification utilization of Cs and MWCNTs, the contact angle decreased significantly from 82.34° to 54.15°. Furthermore, investigation of cell viability, cell metabolism and inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β) proved that the scaffolds not only do not stimulate the immune system, but also polarize macrophage cells from M1 phase to M2 phase. The present study highlights the suitability of 3D printed scaffold PHB/MMBG with Cs/MWCNTs coating for bone tissue engineering.

The Kondo Effect in CexLaLuScY (x = 0.05-1.0) High-Entropy Alloys.

In the search for electronic phenomena in high-entropy alloys (HEAs) that go beyond the independent-electron description, we have synthesized a series of hexagonal rare earth (RE)-based HEAs: CexLaLuScY (x = 0.05-1.0). The measurements of electrical resistivity, magnetic susceptibility and specific heat have shown that the CexLaLuScY HEAs exhibit the Kondo effect, which is of a single impurity type in the entire range of employed Ce concentrations despite the alloys being classified as dense (concentrated) Kondo systems. A comparison to other known dense Kondo systems has revealed that the Kondo effect in the CexLaLuScY HEAs behaves quite differently from the chemically ordered Kondo lattices but quite similar to the RE-containing magnetic metallic glasses and randomly chemically disordered Kondo lattices of the chemical formula RE1xRE21-xM (with RE1 being magnetic and RE2 being nonmagnetic). The main reason for the similarity between HEAs and the metallic glasses and chemically disordered Kondo lattices appears to be the absence of a periodic 4f sublattice in these systems, which prevents the formation of a coherent state between the 4f-scattering sites in the T→ 0 limit. The crystal-glass duality of HEAs does not bring conceptually new features to the Kondo effect that would not be already present in other disordered dense Kondo systems. This study broadens the classification of HEAs to correlated electron systems.

Nonlinear refraction in high terbium content borogermanate glass bulk and fiber

High terbium content glasses have stood out in technological areas due to their simultaneous ability of magnetization and transparency in the visible spectrum. Such magneto-optical glasses are relevant for several optical devices, including optical modulators, sensors, and isolators. While terbium ions are responsible for magnetic response, glass formers, and modifiers provide a branch of desirable mechanical, chemical, and optical properties, which can further be tailored by compositional manipulation. Determination of Verdet constant is usual in magneto-optical glass, however, little attention has been devoted to the determination of the optical properties, moreover the nonlinear ones. Herein, we investigate the nonlinear index of refraction (n2) of a novel magneto-optical glass shaped in bulk and optical fibers. Although the fabrication of fibers with high terbium content is challenging, the usage of optical fibers is important to improve signal that arises from magneto-optical and Kerr effects, since both depend on light propagation path. Bulk and optical fiber of 96(60GeO2-25B2O3–4Al2O3–10Na2O–1PbO) – 4Tb4O7 (mol%) glass were characterized by Z-scan and D-scan techniques, respectively, using femtosecond laser pulses. It was obtained the n2 spectrum in the range of 550–1200 nm for the former, which was modeled based on BGO model, revealing the role of oxygen ions for the optical nonlinearity. The optical fiber fabrication process does not compromise the n2 value, remaining n2=(5±2)×10−20m2/W at 790 nm according to D-scan measurements, which is equivalent to values determined by Z-scan, i.e. (6±2)×10−20m2/W. Additionally, the chemical states of the various elemental components of GBANP-4Tb glasses were investigated by X-ray photoelectron spectroscopy (XPS). The analysis of the Ge 3d and Tb 4f photoelectron spectra of the GBANP-4Tb glasses revealed the presence of Ge4+, Tb3+ and Tb4+ oxidation states. These results are relevant to expand the knowledge on magneto-optical materials, moreover regarding their optical response in the femtosecond regime, broadening its application in ultrafast magneto-optical devices.

A Technique for Magnetic Glass Particle-Mediated Nucleic Acid Extraction from Blood

A Technique for Magnetic Glass Particle-Mediated Nucleic Acid Extraction from Blood

A Technique for Magnetic Glass Particle-Mediated Nucleic Acid Extraction from Blood

A Technique for Magnetic Glass Particle-Mediated Nucleic Acid Extraction from Blood