Magnetic Glass-ceramics Research Articles

Experimental Study on Preparation of Coal Gangue Magnetic Glass-Ceramics by Direct Sintering Method

Experimental Study on Preparation of Coal Gangue Magnetic Glass-Ceramics by Direct Sintering Method

Structure, EPR, and Mössbauer spectra of La0.8Sr0.2FeO3 nanocrystals modified magnetic glass-ceramics

Structure, EPR, and Mössbauer spectra of La0.8Sr0.2FeO3 nanocrystals modified magnetic glass-ceramics

Influence of iron oxide substitution on the magnetic interactions in sol–gel‐derived 45S5 bioactive glass–ceramics

AbstractMagnetic interactions in sol–gel‐derived bioactive magnetic glass–ceramics (MGCs) with compositions of (45 − x)SiO2·24.5CaO·24.5Na2O·6P2O5 xFe2O3 (2 ≤ x ≥ 15 wt.%) have been investigated using electron paramagnetic resonance (EPR), and temperature‐dependent magnetic susceptibility and magnetization (M–T) techniques. EPR spectra of the MGC samples revealed strong composition dependence in the intensity and linewidth of resonance absorptions at g ≈ 2.0 and g ≈ 4.3. EPR linewidth analysis showed the dominance of dipole–dipole interaction in MGC samples with iron oxide content ≤4 wt.% and a crossover to super‐exchange type interaction in samples with higher iron oxide content. Composition‐dependent magnetic interaction in these MGC could be related to Fe2+ and Fe3+ ion concentrations using high‐temperature magnetic susceptibility studies. Zero‐field cooled and field cooled M–T curves indicate different magnetic behavior for MGC samples with x ≤ 6 and x ≥ 8 wt.% iron oxide. Although the former show weak magnetic behavior, the latter exhibit superparamagnetic behavior which could be correlated with the percentage of magnetic phases present in each sample. These studies reveal composition‐dependent variation in dipolar and super‐exchange type interaction in the samples which could help in assessing these MGC for biomedical applications.

Preparation and Crystallization of Magnetic Glass-Ceramics from the Residues after Sulfur Release and Iron Recovery from Copper Ore Tailings with Varied CaO Content.

To comprehensively reuse copper ore tailings (COT), the fabrication of glass‐ceramics by the direct sintering method was investigated, where the residues after sulfur release and iron recovery from copper ore tailings were used as raw materials. The effect of the CaO added on the fabrication of glass‐ceramics was emphasized. After analysis of chemical composition and thermodynamics, crystallization kinetics were analyzed by Differential Scanning Calorimetry (DSC) and fitted to the Kissinger equation. The crystal phase and microstructure of sintered glass‐ceramics heated between 1080 °C and 1100 °C were estimated by X‐Ray diffraction analysis (XRD) and Scanning Electron Microscopy (SEM), respectively. Furthermore, the effects of the addition of CaO on the properties of the sintered glass‐ceramics have been discussed. The results showed that the magnetic glass‐ceramics were sintered by the residues successfully, the color of which was lighter than that of glass‐ceramics sintered by raw materials before iron recovery. According to the XRD analysis, hedenbergite, wollastonite and sekaninaite were formed with traces of maghemite and quartz. In terms of crystallization kinetics and sintering results, a decrease in the activation energies of crystallization and in sintering temperature were observed for an increase in the addition of CaO of up to 10 wt.%. Moreover, the properties of the sintered glass‐ceramics, including bulk density, linear shrinkage and flexural strength, were enhanced, while water absorption and true density were reduced with the increase of the amount of CaO added.

Effect of Cr2O3 on structural and magnetic properties of SiO2–B2O3–Fe2O3–Al2O3–Na2O glass–ceramics

SiO2–B2O3–Fe2O3 magnetic glass–ceramics were prepared by conventional melt quench using a heat treatment method. The effects of Cr2O3 on the phase structure and magnetic properties of the ferrimagnetic glass–ceramics were examined by differential scanning calorimetry, photothermal measurement system, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The magnetic phase of the obtained glass–ceramics was Fe3O4, and the magnetic crystal size and amount of second phase (hematite, Fe2O3) increased with increasing amount of Cr2O3 added. More importantly, the coercivity and saturation magnetization of the sample without Cr2O3 were higher than the samples containing 1–4 wt.% Cr2O3, indicating the spontaneous crystallization capacity of magnetite.

Bioactive glasses and glass-ceramics for hyperthermia treatment of cancer: state-of-art, challenges, and future perspectives.

Bioactive glasses and glass-ceramics are well-proven potential biomaterials for bone-tissue engineering applications because of their compositional flexibility. Many research groups have been focused to explore the utility of bioactive glass–ceramics beyond bone engineering to hyperthermia treatment of cancer. Hyperthermia refers to raising the temperature of tumor close to 44°C at which malignant cells perish with negligible harm to normal cells. Hyperthermia can be employed by many means such as by ultrasonic waves, electromagnetic waves, infrared radiations, alternating magnetic fields, etc. Magnetic bioactive glass–ceramics are advantageous over other potential candidates for thermoseeds such as nanofluids, superparamagnetic nanoparticles because they can bond not only to the natural bone but also with soft tissues in few cases, which helps regenerating the affected part due to its bioactive nature. Strict restrictions on clinical settings (< ) force the research activities to be more focused on material characteristics to raise the implant temperature to required ranges. Lots of efforts have been made in past years to tackle these challenges and design best-suited glass–ceramics for hyperthermia treatment. This review aims to provide essential information on the concept of hyperthermia treatment of cancer and recent developments in the field of bioactive glass–ceramics for cancer treatment. The advantages and disadvantages of magnetic glass–ceramics over other potential thermoseed materials are highlighted. In this field, the major challenges are to develop magnetic glasses, which have fast and bulk crystallization with optimized magnetic phases with lower Curie and Neel temperatures.

Synthesis and characterization of barium hexaferrite (BaFe12O19) nanoparticles from iron ore waste and their possible application in water treatment

In this work hard magnetic glass ceramics has been fabricated using Egyptian Bahariya oasis ore; which contains not less than 51% of its weight as pure iron. High energy planetary ball mill was used to convert the prepared magnetic sample into nanoparticles. Different mechanical milling times were applied to study its effect on the properties of the produced magnetic glass ceramic. Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray florescence analysis (XRF), differential thermal analysis (DTA), X-ray diffraction analysis (XRD), Raman spectroscopy and Vibrating sample magnetometer (VSM) analysis techniques were performed to characterize the prepared glass ceramic samples before and after exposing to mechanical milling process. XRD revealed crystallization of barium hexaferrite as major phase with average crystallite size ∼26 nm. Saturation magnetization Ms depicted 21.2 emu/g after 5 hours milling. The produces nanoparticles after 5 hours milling showed a good performance in removal of pollutants like methylene blue and Congo red from water by adsorption.

Study on the interface between bioactive glass and magnetite

ABSTRACT In this study, in order to reveal the effect of different bioactive glass matrix on magnetic bioactive glass-ceramics (MBGCs), the interfaces between magnetite and three most often used bioactive glass systems, 80SiO2-15CaO-5P2O5 (80S), 58SiO2-36CaO-6P2O5 (58S), and 35SiO2-50CaO-7P2O5-7MgO-1CaF2 (35SM), were prepared and analyzed. Moreover, the phase composition, magnetic structure, and in vitro reactivity of the corresponding glass/ferrite composites with 29 wt% ferrite were investigated. The results showed that Fe migrated into the glass matrix much faster than Si moved into the ferrite phase. Moreover, 58S and 80S glass displayed much stronger interfacial reactions with the ferrite than 35SM glass. Furthermore, the Mössbauer spectra revealed that the 35SM/ferrite composite, showing a saturation magnetization of 3.88 A·m2/kg, had about 29% Fe ions remained the magnetic structure and MgFe2O4 was detected, while all Fe ions were found to be in the paramagnetic structure in the other two composites. Additionally, continuous deposit layers covered all the three composite surfaces after being soaked in simulated body fluid for 14 days. Therefore, when used as MBGC glass matrix, the 35SM glass seemed to be more beneficial to the magnetism. The results of this study are helpful in the design and optimization of MBGCs.

Bioactive magnetic glass-ceramics for cancer treatment

Abstract After five decades of research on bioactive glasses and glass-ceramics, these materials became of considerable interest due to their revolutionary potential for numerous health applications, including cancer treatment. One advantage of glass-ceramics compared with other materials – such as metallic alloys and polymers – is their capability of being highly bioactive and, if desired, containing magnetic phases. Hyperthermia (HT) is an alternative for treating cancer; the strategy is to increase the temperature of the tumor using an external magnetic field that increases the temperature of an implanted magnetic material, which works as an internal heat source. This local increase of temperature, ideally to ~43°C, could kill cancer cells in situ without damaging the healthy surrounding tissue. To achieve such goal, a material that presents a balance between proper magnetic properties and bioactivity is necessary for the safe applicability and successful performance of the HT treatment. Certainly, achieving this ideal balance is the main challenge. In this article we review the state-of-the-art on glass-ceramics intended for HT, and explore the current difficulties in their use for cancer treatment, starting with basic concepts and moving onto recent developments and challenges.

Crystallization of magnetic particles in nNa2O-9SrO-6Fe2O3-8B2O3 (n = 1 and 4) glasses

Abstract Magnetic glass-ceramics with composition nNa2O-9SrO-6Fe2O3-8B2O3 (n = 1 and 4) were prepared by fast quenching of the molten oxide mixtures and subsequent thermal treatment of the obtained glasses at 450–950 °C. The samples were investigated by differential thermal analysis, x-ray powder diffraction, electron microscopy, and SQIUD magnetometry. Increasing of the sodium oxide content leads to a significant decrease of the glass transition, devitrification, and melting temperatures. Just above the glass transition temperature (525 °C for n = 1 and 430 °C for n = 4) superparamagnetic γ-Fe2O3 nanoparticles precipitate, which, at elevating annealing temperature, are substituted by thin hexaferrite nanoplatelets with coercivities of 2000–4000 Oe; the annealing at higher temperatures results in crystallization of the submicron hexaferrite particles with a coercivity of up to 6000 Oe. Thus the glass-ceramics are highly applicable sources of non-sintered nanoparticles with various morphologies and magnetic properties.

Magnetic properties of magnetite-based nano-glass-ceramics obtained from a Fe-rich scale and borosilicate glass wastes

Magnetite-based glass-ceramic is a special composite material composed by magnetic nanocrystals embedded in a vitreous matrix. In this work, it was developed magnetic glass-ceramics based on borosilicate glass wastes and, for the first time, by using iron-rich scale (a waste from the metallurgical industry). Different compositions were established with increasing scale contents (20, 30, 45 wt%). Raw materials were melted (1550 °C/4 h) and later cast in a preheated steel mold at 400 °C. Then, the obtained samples were heat-treated at 700 °C/ 30 min. The sample with 45 wt% scale also was heated at 800 °C and 900 °C/ 30 min, in order to promote more crystallization. The obtained glass-ceramics properties were investigated using X-ray diffraction (XRD), Raman spectroscopy, vibrating-sample magnetometer (VSM), Mössbauer spectroscopy and transmission electron microscopy (TEM). Magnetite nanocrystals (average size in the 40–64 nm range) in the glass-ceramics were evidenced by TEM images and Mössbauer spectrum. VSM analysis revealed that the obtained ferrimagnetic glass–ceramic with composition of 45 wt% scale annealed at 800 °C/ 30 min, improved the magnetic saturation (Ms), reaching 42 emu/g. Results indicated a great potential of this magnetic-based glass-ceramics for being applied in many applications, such as the biomedical engineering field, in magnetic devices, magnetic resonance imaging contrast agents, hyperthermia, waste sorbent, and microwave devices.

Preparation of magnetic glass-ceramics by crystallization of ternary eutectic Li2O-MgO-SiO2 system reformed with some di-and trivalent oxides

This work sheds light on influence of replacing MgO by SrO, MnO or Fe2O3 on the crystallization and magnetic properties of glass-ceramics based on the ternary Li2O-MgO-SiO2 eutectic (935 ± 10 °C) system. Moreover, the effect of adding Al2O3 was also studied. All the glass samples were prepared by the conventional melting technique. Magnetic hysteresis cycles were analyzed using a vibrating sample magnetometer with applied magnetic field up to 20 kOe at room temperature. The bulk density and Vicker microhardness were also evaluated. The crystalline phases formed are lithium meta- and di-silicate, MgSiO3, SrSiO3, Sr-akermanite (Sr2MgSi2O7), β-MnSiO3 and four crystalline phases of pyroxene type like Kanoite-MgMnSi2O6, β-spodumene and Li-aegirine (LiFeSi2O6) with its solid solution (Li,Mg)FeSi2O6. Spinel-LiFe5O8 magnetic phase was also detected. The density values of the examined glass-ceramics are between 2.48 and 2.91 g/cm3. A dense fine microstructure provides superior hardness glass-ceramics up to 6523 MPa is also obtained. The obtained magnetization data is mainly related to the nature of crystalline phases formed and the resulting microstructure. The results reveal an improvement in the magnetization and mechanical properties which render the prepared glass-ceramics useful for hyperthermia treatment of cancer-like bone tumors and for electronic devices as magnetic disk substrates.

The effect of Fe contents on the local structure and crystallization behavior of SiO2–CaO–P2O5–Fe2O3 glasses

The glass and glass ceramics containing SiO2–CaO–Fe2O3–P2O5 were prepared by sol–gel method. The influence of the Fe contents on the crystallization and local structure of the glass and glass ceramics was systematically investigated. The crystal structure of the glass ceramics was identified by XRD characterization. Hematite phase can be precipitated from the glass matrix in all glass ceramics with various Fe contents, and the crystallographic parameters of hematite were determined by XRD Rietveld refinement. The crystallization kinetics of the glasses was investigated in detail. Relative low activation energies were obtained at low Fe contents. The local structure evolution of the glass and glass ceramics has been studied in-depth by means of FTIR and Mossbauer spectroscopy. Fe element is present both as network former and network modifier which significantly influenced the crystallization activation energies of the glasses. The results of this work may be of great significance for the material design and practical applications of bioactive magnetic glass ceramics for hyperthermia.

The effect of zinc substitution on the magnetism of magnesium ferrite nanostructures crystallized from borate glasses

Glasses in the system 51.7 B2O3/9.3 K2O/1 P2O5/10.4 Fe2O3/(27.6–x) MgO/ x ZnO (with x=0, 5, 10, 13.8 and 20mol%) were prepared by the conventional melt quenching method. The as prepared glass samples were thermally treated at 560°C for 3 or 6h. The effect of substituting MgO by ZnO in the glass network on the crystallized phase was studied. The resulting magnetic glass ceramics were characterized using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM) including energy dispersive X-ray analysis (EDX). The substitution of Mg by Zn resulted in a larger lattice parameter of the precipitated crystals, while the crystallite size does not change significantly. TEM micrographs, recorded from extracted particles, showed the formation of small aggregates with about 30nm in diameter. These agglomerates contain crystals with sizes in the range from 7 to 9nm. EDX measurements proved the incorporation of Zn2+ ions into the crystal phase. Room temperature magnetic measurements of the samples with up to 10mol% ZnO showed hysteresis loops which are characteristic for super paramagnetic (SPM) behavior. A magnetic contribution was not detected for samples with higher ZnO concentrations. The maximum magnetization varied with the composition of the glass ceramics to a great extent.

Crystallization of MgFe2O4 from a glass in the system K2O/B2O3/MgO/P2O5/Fe2O3

Spherical magnetic Mg-Fe-O nanoparticles were successfully prepared by the crystallization of glass in the system K2O/B2O3/MgO/P2O5/Fe2O3. The magnetic glass ceramics were prepared by melting the raw materials using the conventional melt quenching technique followed by a thermal treatment at temperatures in the range 560–700 °C for a time ranging from 2 to 8 h. The studies of the X-ray diffraction, electron microscopy and FTIR spectra confirmed the precipitation of finely dispersed spherical (Mg, Fe) based spinel nanoparticles with a minor quantity of hematite (α-Fe2O3) in the glass matrix. The average size of the magnetic nano crystals increases slightly with temperature and time from 9 to 15 nm as determined by the line broadening from the XRD patterns. XRD studies show that annealing the glass samples for long periods of time at temperature ≥604 °C results in an increase of the precipitated hematite concentration, dissolution of the spinel phase and the formation of magnesium di-borate phase (Mg2B2O5). For electron microscopy, the particles were extracted by two methods; (i) replica extraction technique and (ii) dissolution of the glass matrix by diluted acetic acid. An agglomeration of the nano crystals to larger particles (25–35 nm) was observed.

Transforming submerged-arc welding slags into magnetic glass-ceramics

Submerged-arc welding slag (SAWS) and rice husk (RH) wastes represent two particularly abundant metallurgical and agricultural wastes. This work focusses on the feasibility of SAWS, together with glass cullet and RHs, to develop lightweight porous glass–ceramics that could be useful for technical purposes. Effects of temperatures and amounts of RHs on the porosity and water absorption of porous glass–ceramics were discussed at various dosages of husks up to 20 wt%. Depending on the sintering temperature, XRD measurements confirmed the presence of more than two crystalline phases: diopside, jacobsite, MgAl2O4, Ca1.82Al3.64Si0.36O8 and pyrope. These samples exhibited magnetic properties which were related to the presence of jacobsite phase. Magnetization curve is a characteristic of soft ferromagnetic materials with magnetization saturating at ~0.82 emu/g. The present results show a promising way to treat submerged-arc welding slags, transforming it into useful porous and functional glass–ceramic products via a simple powder technology and sintering approach.

Recycling of Iron Sintered Wastes Into Nanoparticles Barium Hexaferrite and Zinc-Ferrite Glass-Ceramics

About 25 % of iron oxides in the sintering process are wastes. In this paper, sintered waste (SW) was used as a source of iron oxides to prepare both hard and soft magnetic glass-ceramics via a melting-quenching technique. About 71 % by wt. of sintered waste was used for preparing soft magnetic glass-ceramics, while ∼46 % was used for preparing hard magnetic glass-ceramics. The comparison between ferrimagnetic glass-ceramics prepared from pure chemicals and that from sintered waste before and after heat treatment was studied. X-ray diffraction shows crystallization of both hematite and Zn-ferrite phases in sintered waste while pure Zn-ferrite or Ba-hexaferrite phases were crystallized in soft magnetic and hard magnetic glass-ceramics, prepared from sintered waste, respectively. Transmission electron microscopy determined the crystalliza- tion of nano-particles ∼20 nm and <15 nm for soft and hard magnetic glass-ceramics respectively. Vibrating scanning magnetometry revealed a significant increase in saturation magnetization from ∼26 emu/g for sintered waste to ∼44 emu/g in soft magnetic glass ceramics while it decreased to ∼12 emu/g for hard magnetic glass-ceramics.

Yb3+/Tb3+ co-doped GdPO4 transparent magnetic glass-ceramics for spectral conversion

Tb3+ and Yb3+ ions co-doped transparent phosphate glass-ceramics containing monoclinic GdPO4 nanocrystals were successfully synthesized using a conventional high temperature melting quenching method in air atmosphere. The structure and morphology properties were systematically analyzed by recording X-ray diffraction patterns and transmission electron microscopy images, which indicate the GdPO4 glass-ceramics was well formed. The luminescent properties of the GdPO4: Yb3+, Tb3+ were investigated based on excitation, emission spectra and decay curves. All samples exhibited the emission of Tb3+ ions from 5D4 → 7FJ (J = 6, 5, 4 and 3) and 5D3 → 7FJ (J = 6, 5 and 4) under irradiation with ultraviolet and near infrared light. Specially, strong green up-conversion emission of Tb3+ at 543 nm (5D4 → 7F5) is observed. And the decay curves illustrate more efficient UC process in GdPO4 glass-ceramics rather than precursor glass. Energy transfer from Gd3+ to Tb3+ as well as cooperative energy transfer from Yb3+ pair to Tb3+ gives a dual mode luminescence. Laser power dependence of up-conversion shows that two-photon process is responsible for the green emission as expected. Additionally, the paramagnetic property of this material was discussed. The hysteresis plot (M−H) analysis results at room temperature indicate their good paramagnetic property. Based on the above results, the block GdPO4 glass-ceramics have potentials to serve as multifunctional materials applied in laser field materials.

Contribution of some divalent oxides replacing Li2O to crystallization characteristics and properties of magnetic glass–ceramics based on Li2O–Fe2O3–Al2O3–SiO2

Magnetic glass–ceramics based on the Li2O–Fe2O3–Al2O3–SiO2 glass system, were prepared through controlled heat treatment regimes. The effect of MO/Li2O replacements (MO=MgO, MnO, ZnO, CdO) on the crystallization process, physical and magnetic properties of the glasses and glass–ceramics were investigated. The crystalline phases formed in the glass–ceramic were lithium metasilicate (Li2SiO3), β-quartz solid solution (ss) (LiAlSi2O6), lithium ferrite (LiFe5O8), Magnesioferrite (MgFe2O4), Jacobsite (MnFe2O4), Franklinite (ZnFe2O4), lithium zinc orthosilicate (γ-Li2ZnSiO4) and lithium ferrite solid solution Li(Fe,Cd)5O8. The density of the prepared glass samples ranged from 2.69 to 2.88g/cm3, whereas the corresponding crystalline materials had a density between 2.77 to 2.95g/cm3. The microhardness of the glass samples ranged from 4665MPa to 5586MPa and increased to a range of 6268–7042MPa after crystallization. The saturation magnetization (Ms), remanence magnetization (Mr), and coercivity (Hc) of the glass–ceramics varied from 0.83 to 8.24emu/g, 0.11 to 0.97emu/g and 112 to 211G, respectively. The formation of different MFe2O4 spinel ferrite magnetic phases instead of LiFe5O8 led to a greatly enhanced saturation magnetization of the glass–ceramics. Possible use of the prepared glass–ceramics may be realized in microwave and magnetic recording applications as well as in tumors therapy.

Influence of Replacement of B2O3 by SiO2 on the Structure and Magnetic Properties of BaO-Fe2O3-SiO2-B2O3-CeO2 Glass-Ceramics

In this study, a series of magnetic glass-ceramics with the composition of 20BaO-20Fe2O3-xSiO2- (60 − x)B2O3-1CeO2 (x = 0−50, in weight percent) were prepared by conventional melt casting followed by heat treatment method. The crystalline phases, structure, microstructure, and magnetic properties were investigated systematically with the gradual replacement of B2O3 by SiO2. The results indicated that there existed a “boron abnormal phenomenon” due to the variation of [BO3]/[BO4] in the glass-ceramics with xchange, which led to an abrupt transition in magnetic property. With x increasing from 20 to 30, a continuous transition from the paramagnetic to the ferromagnetic nature is observed, in which the values of Ms were enhanced greatly with increasing x. The values of Ms and Mr for the x = 50 sample were 10.930 and 3.527 emu/g, respectively.