Magnetic Properties Of Glasses Research Articles

The impact of NiO on crystallization and thermo-magnetic properties of Li2O–NiO–P2O5 glasses as new magnetic materials

The main goal of this study is to comprehend the effect of the composition change on crystallization characteristics, thermal, physical, and magnetic properties of glasses with the general formula (35 − x) Li2O − (5 + x) NiO − 60 P2O5 (x = 5, 10, and 15 mol%). The XRD results indicated that Li4P4O12, Li6P6O18, Ni2P2O7, Ni2P4O12, and Li3P crystalline phases were formed in the glass ceramics. The NiO/Li2O replacement led to an increase in the coherence of the glass structure. Density values for the glass and glass–ceramic samples ranged from 2.38 to 2.49 g/cm3 and from 2.41 to 2.53 g/cm3, respectively. Coefficients of thermal expansion CTE of the glasses were varied from 157 × 10−7 to 96 × 10−7 °C over the temperature range of 25–250 °C. However, CTE of the glass–ceramic was ranged from 183 × 10−7 to 129 × 10−7 °C over the temperature range of 25–500 °C. VSM analysis for the glasses revealed that the NiO/Li2O replacement led to a decrease in the magnetic parameters of the materials. Contrariwise from VSM hysteresis loops of glass–ceramic, it was found that the magnetic parameters increased with the addition NiO instead of Li2O. The results indicated a great potential of the prepared glasses and glass ceramics as promising soft ferromagnetic materials that can be used in different magnetic applications.

Effect of transition oxides on thermal and magnetic properties of phosphate materials

Low melting point glass are attractive industrial materials due to their high thermal and chemical resistance compared to conventional glass. our study aimed to study the influence of transition oxides such as Fe2O3 and Cr2O3 on the thermal and the magnetic properties of glass. The results of differential scanning calorimetry (DSC) have provided a lot of essential information on the correlation between the chemical composition of glass and their characteristic parameters, such as glass transition temperature, crystallization temperature, melting temperature. We have performed the measurement of X-ray diffraction, IR and RAMAN, Mössbauer spectroscopy, as well as the measurements of density, dissolution rate and activation energy of dissolution. The proportion on transition oxides in the sudied glass ensure the glass thermal stability, the relatively low melting temperature, and a high chemical durabilité, with application potential in nuclear waste immobilization.

Synthesizing CoFe2O4 by Glass-Ceramic Method and Characterizing its Magnetic Properties in Na2O-Fe2O3-CoO-B2O3-SiO2 System

In this investigation, the effect of heat treatment on magnetic properties of glass and nano-structured cobalt-ferrite glass-ceramic was studied. The glass was synthesized in the system of Na2O-Fe2O3-CoO-B2O3-SiO2. Based on DTA results, heat treatment was done at different times and temperatures. X-ray diffraction pattern of glass-ceramic showed the crystallization * یکینورتکلا تسپ ،تابتاکم لوئسم : mirkazemi@iust.ac.ir

Thermal, structural and magnetic properties of zinc-tellurite glasses containing natural ferrite oxide

Natural ferrite oxide doped zinc-tellurite glasses are synthesized using the melt quenching technique at 850°C with chemical composition of (80−x)TeO2·xFe3O4·20ZnO (x=0, 0.5, 1, and 2) in mol%. Precursor nanosized particles of natural magnetite are used as raw material of the ferrite oxide. A differential thermal analyzer, an X-ray diffraction spectroscope and a vibrating sample magnetometer are used to characterize thermal stability, structure, and magnetic properties of the glasses, respectively. The vibrating sample magnetometer reveals the paramagnetic nature of the ferrite oxide with magnetic susceptibility of 4.05×10−5m3kg−1. Incorporation of oxide in the glasses affects the thermal stability factor, structure and magnetic properties of the glasses. The stability factor increases from 69 to 102°C and the glass structure exhibits an amorphous structure. The magnetization curve with a very small hysteresis (Mr=7.0×10−3emug−1, Hc=1.7×10−2T) and high saturation field can be observed on the addition of 2mol% ferrite oxide. This indicates the existence of ferrimagnetic cluster formation in the glass matrices. Our method is new, economic and may contribute towards the development of magneto-optic devices based on zinc-tellurite glasses.

Thermal, structural and magnetic properties of some zinc phosphate glasses doped with manganese ions

(MnO) x ·(P 2O 5) 40·(ZnO) 60− x glasses containing different concentrations of MnO ranging from 0 to 20 mol% were prepared by the melt-quenching technique. The samples had a fixed P 2O 5 content of 40 mol% and the MnO:ZnO ratio was varied. The thermal, structural and magnetic properties of these glasses were investigated by means of differential thermal analysis (DTA), electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. Compositional dependence of the glass transition ( T g), crystallization ( T p) and melting temperatures were determined by DTA investigations. From the dependence of the T g on the heating rate ( a), the activation energy of the glass transition ( E g) was calculated. The fragility index ( F) for the studied glasses was determined to see whether these materials are obtained from kinetically strong-glass-forming (KS) or kinetically fragile-glass forming (KF) liquids. The EPR spectra of the studied glasses revealed absorptions centered at g ≈ 2.0, 3.3 and 4.3. The compositional variations of the intensity and line width of these absorption lines was interpreted in terms of the variation in the concentration of the Mn 2+ and Mn 3+ ions in the glass and the interaction between the manganese ions. EPR and magnetic susceptibility data reveal that both Mn 2+ and Mn 3+ ions are present in the studied glasses, their relative concentration being dependent on the glass composition. Magnetic susceptibility data reveal an antiferromagnetic interaction between the manganese ions for the glasses containing 20 mol% MnO.

Influence of iron ions on the structural and magnetic properties of some zinc-phosphate glasses

Glasses in the (Fe 2O 3) x ·(P 2O 5) 40·(ZnO) 60− x (0 ≤ x ≤ 30 mol%) system have been prepared by the melt-quenching technique. The structural and magnetic properties of these glasses were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The XRD pattern for the prepared samples shows their vitreous state only for x ≤ 20 mol%. For the samples containing 30 mol% Fe 2O 3 the presence of a unique crystalline phase, FePO 4, embedded in an amorphous matrix was evidenced. FTIR spectroscopy data suggest that the iron ions play the network modifier role in the studied glasses. The addition of iron oxide leads to the breakage of P O bonds and the formation of the P–O–Fe bonds. The presence of the Fe–O–P bonds for the samples with higher iron oxide content in the studied system improves their chemical durability. The increases of iron ions content of the samples determine a gradual decrease in the number of bridging oxygen ions respectively the increase of the number of non-bridging oxygen ions. EPR and magnetic susceptibility measurements show the presence of the Fe 3+ ions in sites of distorted octahedral symmetry and as well as in clustered formations containing both Fe 3+ and Fe 2+ ionic species. Dipolar and superexchange interactions involving iron ions were revealed depending on the iron content of the sample.

Effect of Gadolinium on the Structure and Magnetic Properties of Glass and Glass–Ceramic Sillenites

Glass samples belonging to xGd2O3·(1−x)[0.857Bi2O3·0.143GeO2] system, with 0.005≤x≤0.1, have been prepared by the rapid quenching method. Glass–ceramics were obtained after heat treatment of the as‐prepared glasses at 600°C for 24 h. All samples have been structurally characterized by X‐ray diffraction and electron paramagnetic resonance (EPR) spectroscopy. All as‐prepared samples are noncrystalline. The glass–ceramics contain different bismuthate crystalline phases, Bi12GeO20, BiLa type, and Bi24GeO38, depending on the gadolinium content in the glassy sample. The magnetic properties have been investigated by EPR and magnetic susceptibility measurements. The EPR and magnetic susceptibility data suggest that besides homogeneously distributed Gd3+ ions, both in the glass and glass–ceramic samples, there are clustered Gd3+ ions experiencing antiferromagnetic interactions.

Chapter 11 magnetic nanoparticles in oxide glasses

Unique properties of the potassium-aluminum-boron glasses doped with low concentrations of MnO and Fe2O3 to make them magnetically ordered and optically transparent in the IR and visible ranges are due to the formation of nanoparticles of a cubic ferrite. Assembling and properties of nanosized ferrite particles in the glasses have been investigated by X-ray diffraction, differential dissolution analysis, high-resolution transmission electron microscopy, Mossbauer spectroscopy, magnetic measurements, and magnetooptical Faraday effect. It was shown that the ferrite particles vary highly in size, shape, stoichiometry, structural perfection, and space distribution depending on the preparation conditions. A correlation between the characteristics of nanostructured ferrite particles and magnetic properties of glasses has been established.

Tailoring of Magnetic Properties of Glass coated Microwires

ABSTRACTThe magnetic behaviour of the glass-covered metallic microwires with a wide compositional range of composition with soft and hard magnetic character is presented. The effect of conventional furnace and dc current annealing under dc axial magnetic field or without it as well as of a chemical etching on the magnetic properties of Co and Fe-based glass coated microwires has been studied. Such treatments modify the magnetic parameters. In particular, annealing under applied magnetic field (field annealing) can improve significantly such magnetic parameters as permeability. Such phenomenology can be interpreted considering the noticeable magnetic anisotropy induced by the combined effects of the magnetic field and strong internal stresses arising from the coating. Giant magnetoimpedance (GMI) effect was observed in nearly-zero magnetostrictive amorphous microwires. Upon careful heat treatment, FeCuNbSiB amorphous microwires devitrificate into nanocrystalline structure with large variety of magnetic parameters. Hard magnetic materials with coercivity up to 800 Oe were obtained as a result of decomposition of metastable phases in Co-Ni-Cu microwires as well as after crystallization process of FeCuNbSiB amorphous microwires.

Structure and magnetic properties of Bi 2O 3–GeO 2–Gd 2O 3 glasses

In this paper we present a characterisation of the local structure and magnetic properties of glasses in the xGd 2O 3·(100− x)[Bi 2O 3·GeO 2] system by using infra-red (IR), electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The IR spectra indicate that the bismuth and germanium environments in the Bi 2O 3·GeO 2 base glass are not strongly perturbed by gadolinium incorporation up to 30 mol% Gd 2O 3. The EPR spectra of the samples investigated reveal resonance sites with an unexpectedly high crystalline field in addition to the “U” spectrum, typical for Gd 3+ ions in disordered systems. Magnetic susceptibility measurements indicate a Curie type behaviour for x≤3 mol% and above this concentration a Curie–Weiss type behaviour. A model for the gadolinium distribution in bismuth–germanate glasses is suggested, which is consistent with these results.

High field magnetization of glasses

We present large field (to 20 T) magnetization data, in a temperature range 4–80 K, for two types of magnetic ions, one where the concept of the localised moment is applicable, rare-earth ion, e.g. Nd, and other where it is not, the transition metal ions (Fe). We show how the macroscopic magnetization, M( T, H), and the parameters derived from it carry information about the average interaction and about the aggregation of these ions in glasses with composition xFe 2O 3:PbO:2B 2O 3 for x⩽0.6 in formula units. We apply mean field theory (MFT) to the Brillouin function and show how the contribution of the interacting and non-interacting ions can be separated. The analysis of the data yields an effective interaction energy and the number of ions involved in the interaction. The variation of these two parameters allows us to show that the magnetic properties of glasses containing the two types of ions are due to differing distributions of the ions.

Magnetic Properties of Glasses Containing Rare Earths

Magnetic Properties of Glasses Containing Rare Earths

Magnetic and structural properties of iron-based oxide glasses, Fe 2O3-BaO-B2O3, from 57Fe Mössbauer spectroscopy

57Fe Mossbauer spectroscopy has been combined with bulk results to determine the electronic configuration of iron, the short-range structural order and the magnetic properties of glasses in the system (Fe2O3)x(BaO)y(B 2O3)z. The average coordination of the iron atoms is determined by the Fe/O atomic ratio while the valence state of Fe seems to be affected essentially by the preparation conditions. Structural short-range order around Fe atoms is concluded to be very strong, with random bonding angle and distance fluctuations. At low Fe2O3 content, the glass is paramagnetic down to 1.5 K. Local moment measurements reveal the coexistence of isolated Fe ions and of atomic scale clusters. At intermediate Fe2O3 concentration (~ 25 %), the glass presents a mictomagnetic transition. At large Fe2O3 content (~ 50%), the glass behaves like a superparamagnet, indicating inhomogeneous distribution of the Fe atoms in the solid. Mossbauer spectroscopy is also applied to the investigation of the crystallization of a glass with intermediate Fe2O3 concentration.

Magnetic properties of the ternary oxide glasses, Li2O-B2 O3-Fe2O3 from 57Fe Mössbauer spectroscopy

57Fe Mossbauer spectroscopy has been combined with bulk magnetic measurements to determine the valence state and coordination of iron as well as the magnetic properties of the ternary oxide glasses, Li2O-B 2O3-Fe 2O3. In all investigated glasses (≤ 8.4 at % Fe), the Fe3+ ions coexist in tetrahedral and octahedral coordinations ; the presence of Fe2+ ions ( < 15 %), which is observed in some glasses, is related to preparation conditions. The magnetic properties of the glasses are governed by the iron content. At low iron concentration (< 3 at %), isolated Fe3+ ions coexist with antiferromagnetic dimers and trimers. At large iron content (3.8 to 8.4 at %) the glasses undergo a mictomagnetic transition to a speromagnetic ordered state. The freezing temperature (Tf), which is frequency dependent, is found to follow a Fulcher law in one sample (5.8 at % Fe) investigated in detail.