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Composites of NiFe2O4 (NFO)–BaTiO3 (BTO) and NiGd0.01Fe1.99O4 (G0.01)–BTO were investigated by x-ray diffraction, magnetization, transmission electron microscopy, magnetocapacitance, and ferroelectric studies. NFO and G0.01 nanoparticles were synthesized by the sol-gel method. The crystallite size of the nanoparticles estimated from the x-ray diffraction patterns is 20–22 nm. The average crystallite sizes of NFO and G0.01 nanoparticles were estimated from the transmission electron micrographs as 26 (1) nm and 22.3 (0.3) nm, respectively. These nanoparticles were encapsulated in a BTO shell, resulting in the formation of nanocomposites. Room temperature magnetization (at 60 kOe) of G0.01 nanoparticles was found to be slightly higher than that of NFO nanoparticles, due to the larger moment of Gd3+ than that of Fe3+. Also, the magnetization of G0.01–BTO is more than that of NFO–BTO nanocomposites. The magnetoelectric effect was observed with a magnetocapacitance value of approximately −10% at 10 kHz in both the composites. [ABSTRACT FROM AUTHOR]

The electrical and Hall resistivities of TbxFe100-x thin films in the temperature range 13–300 K were investigated. The sign of Hall resistivity at 300 K is found to change from positive for x=28 film to negative for x=30 film, in accordance with the compensation of Tb and Fe moments. All the films are seen to have planar magnetic anisotropy at 13 K. The temperature coefficients of electrical resistivities of the amorphous films with 19≤x≤51 are seen to be negative. The temperature dependence of Hall resistivity of these films is explained on the basis of random magnetic anisotropy model. The temperature dependences of Hall resistivities of the x=22 and 41 films are seen to exhibit a nonmonotonous behavior due to change in anisotropy from perpendicular to planar. The same behavior is considered for the explanation regarding the probable formation of Berry phase curvature in these films. [ABSTRACT FROM AUTHOR]

It had been reported that B has beneficial effects on the magnetostriction of anisotropy compensated Dy0.7Tb0.3Fe2 alloys. In the present work, Dy0.7Tb0.3Fe1.95 and Dy0.7Tb0.3Fe1.95Bx (x=0.1, 0.15, and 0.2) alloys, in the form of 8 mm diameter cylindrical rods, were investigated both in the as-cast and zoned conditions. At 5 kOe dc magnetic field, magnetostriction of ∼1200 and 900 microstrains was observed for zoned samples with x=0 and 0.1, respectively. For zoned samples with x>0.1 and for the as-cast sample of the parent alloy, magnetostriction of ∼500 microstrains was measured. X-ray diffraction of the zoned x=0 and x=0.1 samples showed a strong prevalence of the <112> and the <110> grain orientations; in contrast, the other samples appeared to possess a random grain orientation. Optical and scanning electron microscopy studies revealed a significant increase in the volume fraction of the RFe3 phase with increasing boron content. This increase in the volume fraction of the (Tb,Dy)Fe3 phase and the reduction in the desired grain orientation of the (Tb,Dy)Fe2 phase are attributed to be the reasons for the large decrease in the magnetostriction of the (Tb,Dy)Fe1.95 alloys with boron addition. [ABSTRACT FROM AUTHOR]

An intermetallic compound of nominal composition Tb0.3Dy0.7Fe1.95 was conventionally cast in the form of cylindrical rods of 8 mm diameter and directionally solidified by zoning at three different growth rates. Compounds of the same nominal composition were also directionally solidified in the form of cylindrical rods of 20 mm diameter by modified Bridgman technique, at two different growth rates. The microstructure of the directionally solidified compounds has been investigated as a function of solidification rate and compared with that of conventionally cast compound. The observed microstructural features of these samples have been correlated with the magnetostriction measured on the corresponding samples. Further, by examining the longitudinal sections cut along its cylindrical axis, a correlation of microstructure with magnetostriction has been brought out for each directionally solidified sample as a function of distance from the initially solidified end to the other. It has been observed that a large magnetostriction (at 4.5 kOe) and a high initial slope of magnetostriction versus applied magnetic field are realized in the directionally solidified samples as compared to the conventionally cast sample. An improvement in the property has been observed among the directionally solidified samples when solidified with higher growth rates. It is surmised on the basis of the observed microstructural features in this study that a large magnetostriction is realized if formation of (Tb,Dy)Fe2 occurs by congruent solidification rather than by the peritectic reaction L+(Tb,Dy)Fe3→(Tb,Dy)Fe2. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of SmTbFe17-xAlx (x=0–8) and SmTbFe17-xSix (x=0–3.5) were investigated by x-ray-diffraction and magnetization studies. All the compounds stabilize in rhombohedral structure. The lattice parameters are found to increase with Al substitution whereas they are found to decrease with Si substitution. The rates of the decrease of saturation magnetization (Ms) value with the substitution of Al and Si are almost the same. The easy direction of magnetization (EMD) is in the ab plane up to an Al concentration of x=7 and has a tendency to shift towards the c axis at x=8. All the compounds with Si are seen to have the EMD in the ab plane. Electron-magnon scattering is seen to contribute to the electrical resistivity in both Al- and Si-substituted compounds; in the temperature range of 30–60 K and at higher temperatures, scattering due to phonons is observed. [ABSTRACT FROM AUTHOR]

This study describes the relative effect on the permanent magnet characteristics viz. remanence (B,.), intrinsic coercivity (H[SUBci]), Curie temperature (T[SUBc]), and rectangularity of the intrinsic demagnetization curve, when A1, Cu, Ga, and Nb are added individually to NdFeB. Each elemental addition causes significant improvement in H[SUBci] but the level of improvement differs from one additive element to the other. The addition of Nb is favored over other elements for realizing maximum enhancement in H[SUBci] and rectangularity of the demagnetization curve. The microstructural features of the sintered samples of NdFeB with elemental addition show the formation of a new phase, in addition to the phases (φ η, and Nd-rich) generally found in the ternary sample. The factors influencing the permanent magnet characteristics of sintered samples are the distribution of the Nd-rich phase in the intergranular region, the size and distribution of the minor phases at the grain junctions, the formation and distribution of new phases due to alloying addition, and the solubility of the dopant element in various phases coexisting in the sample. [ABSTRACT FROM AUTHOR]

The influence of addition of Co on the structural and magnetic properties of MnSb was investigated. The compound formed in the NiAs-type hexagonal structure. Addition of Co to MnSb causes changes in both the lattice parameters. It was observed, from magnetization measurements, that both Curie temperature and saturation magnetization decrease from those of MnSb. The spin-polarized density of states (DOS) calculations revealed that the intermetallic compound favors ferromagnetic ground state even after as much as 0.25 atom of Co per formula unit of MnSb. Charge transfer takes place from the interstitial Co-atom to minority spin band of Mn-atom resulting in an increase in the DOS compared to MnSb at the Fermi level. MnSbCo0.25 exhibits a negative magnetocaloric effect with the largest change in the entropy value, ΔSm = 2.5 J. kg-1. K-1 (for a change in magnetic field from 0 to 5 T), across the second order phase transition at 292 K. The change in the value of magnetic entropy is low around the phase transition and might be due to the small magnetic moment of Mn-atom. [ABSTRACT FROM AUTHOR]

Magnetization studies were carried out on Tb–Fe and Tb–Fe–Co thin films, prepared using magnetron co-sputtering technique. The films Tb25Fe75 and Tb31Fe69 were found to have perpendicular magnetic anisotropy (PMA) both at 25 and 300 K. In Tb–Fe–Co films, all the films were observed to exhibit planar anisotropy at 25 K, due to the increase of strain-induced anisotropy as a result of large magnetostriction at low temperatures leading to the development of in-plane anisotropy. PMA was observed in the films Tb35Fe37Co28, Tb56Fe25Co19, and Tb63Fe20Co17 at 300 K. The Curie temperatures (TC) of both TbxFe100–x and Tb–Fe–Co films were found to be above room temperature (RT). Observing the Curie temperatures well above the RT, with the existence of PMA at RTs, is an interesting object in these films to find in magnetic data storage applications. [ABSTRACT FROM AUTHOR]

The nitrogen-incorporated nickel ferrite (N-NFO) thin films deposited by radio-frequency magnetron sputtering were found to exhibit interesting magnetic properties upon heat treatment. The in-plane (IP) and out-of-plane (OP) magnetizations of the heat-treated N-NFO thin films measured at 20 K were seen not to saturate even at higher fields, indicating a large perpendicular magnetic anisotropy (PMA). The coercive field value was found to decrease upon heat treatment, due to the weakened pinning of domain walls upon decrease in grain boundary volume. The IP magnetization exhibits a tendency to saturate at high fields, whereas the OP magnetization does not, indicative of the existence of easy magnetization direction in the plane of the film. The room temperature ferromagnetic resonance (FMR) spectra in both IP and OP configurations indicated the increase of FMR linewidth upon nitrogenation, revealing the increased distribution of magnetic anisotropy induced by nitrogen in the lattice. An increase in the resonance field value was observed for the N-NFO film grown at 100 W compared with that of NFO in the IP configuration, while a decrease in the value was observed for OP, which is attributed to an enhanced IP magnetic anisotropy. The films grown at 120 and 140 W have shown decrease in a resonance field value in the IP configuration and increase in OP, which is attributed to the increase in thickness-dependent PMA. [ABSTRACT FROM AUTHOR]

Presents a study that measured the magnetostriction and magnetochemical coupling coefficient on Ho[sub0.85]Tb[sub0.15]Fe[sub2-x]Co[subx] alloys. Impact of the increase of cobalt concentration on saturation magnetostriction and magnetomechanical coupling coefficient; Determination of magnetomechanical coupling coefficient; Change in the easy direction of magnetization.

Presents a study which examined the effect of hydrogen on the magnetic properties of holmium[sub0.85]terbium[sub0.15]iron[sub2] and dysprosium[0.73]terbium[0.27]iron[sub2]. Magnetization measurements; Experimental details; Results and discussion.

NiFe2O3 and NiOFe1.925Sm0.075O3 thin films were prepared by rf magnetron sputtering on oxidized silicon and lead zirconate titanate (PZT) substrates. Both the films were found to crystallize in inverse spinel structure after the annealing was carried out at 1073 K for two hours. Small hysteresis was observed in both the films at 300 K as well as 1.8 K. The magnetoelectric coefficient αE is seen to have the largest value at 500 Oe and is 4.07 and 3.57 mV cm-1 Oe-1 in NiOFe1.925Sm0.075O3-PZT and NiOFe2O3-PZT composite films, respectively. [ABSTRACT FROM AUTHOR]

A systematic investigation of the influence of Al and V on the magnetoimpedance (MI) effect in melt-spun Fe73.5Si13.5B8CuNb(3-x)VxAl (x=0, 1, 1.5, and 3) ribbons has been performed in the frequency range 500 kHz-13 MHz and under dc magnetic field (Hdc) up to 60 Oe. MI was measured using impedance analyzer employing contact and noncontact methods. MIs of 61% (contact method) and 104% (noncontact method) were observed for the x=1.0 ribbon. Transverse and in-plane anisotropies were studied from the MI measurements and ferromagnetic resonance. Magnetic domain structure was studied in the ribbons through magnetic force microscopy. When the ribbon was rotated by 90° from the east-west direction, a 37% change in the MI was observed due to the earth's magnetic field. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Tb0.1Ho0.9-xPrx(Fe0.9B0.1)2 (x=0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, and 0.4) compounds are investigated. The compounds with 0<=x<=0.25 are found to stabilize in single cubic Laves phase structures. Small quantities of the (Tb,Ho,Pr)2Fe14B phase and rare-earth phases for x>=0.3 and also the (Tb,Ho,Pr)(Fe,B)3 phase for x>=0.35 are observed along with the Laves phase. The saturation magnetization and Curie temperature are found to decrease with Pr content. However, the magnetostriction (at 10 kOe) is found to increase with Pr content. The x=0.15 compound is found to exhibit a possible anisotropy compensation between the (Tb/Ho) and Pr sublattices. The easy magnetization direction (EMD) is found to rotate toward <113> as the Pr content increases, up to x=0.25, and for x>=0.35 there is a tendency for the EMD to shift toward <111>. [ABSTRACT FROM AUTHOR]

We have studied structure, transport, and magnetic properties of NdxBi0.5-xSr0.5MnO3 (NBSMO) (x=0.2 and 0.4) through x-ray diffraction, magnetoresistance, and magnetization measurements. The Rietveld analysis of the x-ray diffraction data shows that the NBSMO crystallizes in an orthorhombic perovskite structure with Pbnm space group for x=0.2 and Imma space group for x=0.4. The lattice variations indicate that the highly polarizable 6s2 lone pair of Bi ion is screened and the structural changes occur in accordance with change in the average radius of A-site cations. Magnetotransport studies reveal that both samples are variable range hopping semiconductors and the hopping depends on the orientation of localized spin moment of the electrons. Magnetic studies confirm that substituting Bi with Nd collapses the charge ordered antiferromagnetic (AFM) state of Bi0.5Sr0.5MnO3 to ferromagnetic state, with TC’s∼276 and ∼278 K, for x=0.2 and 0.4, respectively. The observed enhancement in colossal magnetoresistance effect in NBSMO compared to Bi0.5Sr0.5MnO3 is attributed to the presence of competing ferromagnetic and charge ordered AFM state. [ABSTRACT FROM AUTHOR]

Ferromagnetic and ferroelectric characteristics of Gd substituted nickel ferrite (NiO·Fe1.925Gd0.075O3) were investigated. The material formed in the cubic inverse spinel phase and in addition, a small amount of GdFeO3 phase was identified. A small distortion of the cubic lattice was observed upon the substitution of Fe by Gd in the B site. Substitution of Gd for Fe lowered the saturation magnetization. However, the saturation magnetostriction is seen not to change significantly by the substitution of Gd. From the temperature variation of dielectric constant measurement, the ferroelectric transition temperature was found to be 512 K. The existence of the ferroelectricity was confirmed from the ferroelectric loop. The (high) dielectric constant with frequency is seen to reveal a dispersion of relaxation times. [ABSTRACT FROM AUTHOR]

The pseudobinary Laves phase R1R2Fe2 magnetostrictive compounds have one degree of freedom by which the largest anisotropy constant K1 is minimized to obtain the best performing material. However, by including a third rare earth element, additional degree of freedom is obtained, which allows a better way to choose a material for application. In the present study, Ho has been chosen as it exhibits positive magnetostriction, similar to Tb and Dy. Substitution of Mn for Fe leads to the realization of improved magnetostriction values and reduction in the anisotropy. In the present paper magnetic properties of Tb0.28Dy0.57Ho0.15Fe2-xMnx(x=0,0.05,0.1,0.15,0.2) are presented. The compounds have formed in single phase with cubic Laves phase structure. The lattice parameter is found to increase from 7.327 to 7.347 Å with increasing the Mn concentration to 0.2. The Fe/Mn–Fe/Mn distance is less than 2.66 Å, the critical distance below which the Fe and Mn moments could be antiferromagnetically ordered, leading to a decrease in the Curie temperature from 592 to 537 K. At 80 K, saturation magnetization is found to increase from 120 emu/g (x=0) to 125 emu/g (x=0.1) and then to decrease to 105 emu/g (x=0.2). The magnetostriction increases from 1000×10-6 (x=0) to 1050×10-6 (x=0.1) with Mn and decreases to 775×10-6 with further increment of Mn (x=0.2). Spontaneous magnetostriction is found by the splitting of the (440) peak. [ABSTRACT FROM AUTHOR]

The effect of Al on the structural and magnetic properties of Pr3(Fe1-xAlx)27.5Ti1.5 (x=0.1, 0.2, and 0.3) compounds has been investigated by x-ray-diffraction, magnetization, and Curie temperature measurements. All these compounds have formed in monoclinic symmetry with A2/m space group with Pr(Fe,Ti)12 as secondary phase and traces of α-Fe. The monotonic decreases in MS both at 300 and 80 K are discussed on the basis of electron transfer from the 3p band of Al to the 3d band of Fe near EF. The variations in TC are explained using the Friedel approach. In all the compounds, the easy magnetization direction is away from the b axis. [ABSTRACT FROM AUTHOR]

The effect of conventional annealing and Joule annealing on magnetoimpedance (MI) of Co68Fe5Si12B15 ribbons was studied. The ribbons used for the MI measurements were 1 and 5 cm long. The as cast 5-cm-long ribbons exhibit a larger MI compared with the 1-cm-long ribbons, at all frequencies. The maximum MI of the as cast ribbons of 5 cm length is 17% at 600 kHz whereas for the 1-cm-long ribbons it is 3% at 500 kHz. Conventional annealing carried out at 200 and 300 °C for 1 h results in the decrease of the MI in both the 5 and 1-cm-long ribbons, respectively. The Joule annealing of the 5-cm-long ribbons employing a current of 500 mA for 5 min. causes the increase of the MI to 26% at 800 kHz. For the 1 cm Joule-annealed ribbon, employing a current of 500 mA for 5 min., the maximum MI observed is 6% at 500 kHz. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Nd3(Fe1-xAlx)27.5Ti1.5 (x=0.1–0.4) were investigated by x-ray diffraction, magnetization, and Curie temperature (TC) measurements. The unit cell volume increases with the Al substitution, in accordance with the larger atomic radius of Al. The saturation magnetization and the Curie temperature decrease with increasing Al content, and the decrease is attributed to the modification of the density of states of 3d band due to the 3p band of Al and to the magnetic dilution effect. The easy direction of magnetization is along the b axis for x=0.4. The anisotropy field (HA) decreases with increasing Al concentration. [ABSTRACT FROM AUTHOR]

The effect of Ga/Al substitution on the structural and magnetic properties of YGdFe17 has been investigated. A structural transformation from hexagonal to rhombohedral has been observed. The saturation magnetization increases up to x=1 (Ga)/2 (Al) and then decreases with further increase of x. Curie temperature increases from 476 K for YGdFe17 to 595 K for YGdFe14Ga3 and 495 K for YGdFe14Al3 and decreases with further substitution of Ga/Al. The easy magnetization direction is planar up to x=6 for Ga- and 7 for Al-substituted compounds and shifts to along c axis for x=8. [ABSTRACT FROM AUTHOR]

Magnetic properties of (Sm0.5Tb0.5)2Fe17-xGax [mentioned subsequently as SmTbFe17-xGax] have been investigated. All the compounds have formed in rhombohedral Th2Zn17 structure with traces of α-Fe. The saturation magnetization decreases with increasing x and is attributed to the modification of the density of states of 3d band due to the low lying 3p band of Ga. The increase of Curie temperature up to x=3 and subsequent decrease is explained on the basis of band narrowing. The easy direction of magnetization is in the ab plane up to x=5 and changes along the c axis for x =7. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of (Sm0.9Pr0.1)3(Fe1-xAlx)27.5Ti1.5 [x=0.1, 0.2, 0.3] compounds have been investigated by x-ray diffraction, magnetization, and Curie temperature measurements. The lattice parameters are found to increase with increasing Al concentration. The saturation magnetization is seen to decrease with the substitution of Al and is attributed to the modification in the DOS by Al. The Curie temperature increased for low concentrations of Al and then decreased. The easy direction of magnetization (EMD) in all the compounds is normal to the (204) plane. The anisotropy fields decrease with increasing Al concentration. [ABSTRACT FROM AUTHOR]

Studies the effects of cobalt substitution on magnetic properties of intermetallic compounds with praseodymium and titanium. Details on the nature of the anisotropy fields; Experimental details; Results and discussion.

In this paper, carbon (C) and nitrogen (N) were incorporated into the interstitial sites of nickel (Ni) ferrite lattice. Structural studies of the incorporated NiFe2O4 (NFO) samples (C-NFO and N-NFO) using X-ray diffraction revealed changes in the values of the lattice parameter, bond angle, and bond length. Raman spectroscopic studies revealed shifts in peak positions of \textEg and \textT2g (3) vibrational modes of the spectra. Magnetization measurements at 20 and 300 K using vibrating sample magnetometer showed decrease in the values of Ms upon incorporation of C/N ( 2.3~\mu B /f.u. of C-NFO and 2.4~\mu B /f.u. of N-NFO from 2.9~\mu B /f.u. of NFO, at 20 K). An increase in intrinsic coercive field ( Hc ) value (18.2 Oe of C-NFO and 14.2 Oe of N-NFO from 5.2 Oe of NFO, at 20 K) was also observed. However, a reduction in the value of first-order cubic magnetocrystalline anisotropy constant ( K1 ) was observed upon incorporation of C/N. Microstructural analysis using scanning electron microscopic images revealed modifications in the shape and the size of the grains. The average grain size was found to be reduced upon C/N incorporation (~600 nm of NFO, while ~550 nm of C-NFO and ~400 nm of N-NFO). [ABSTRACT FROM AUTHOR]

The pure as well as nitrogen incorporated nickel ferrite (NFO and N-NFO) thin films were grown by radio frequency magnetron sputtering technique. The structural investigations of as-grown N-NFO films using GIXRD and Raman spectroscopy revealed nanocrystalline nature of the films. The microstructural and surface studies of the films using SEM and atomic force microscope micrographs showed increase in crystallite size and decrease in surface roughness with increase of sputtering power. The magnetization (M-H) measurements at 20 and 300 K revealed an increase in magnetization and decrease in coercivity values with increase of sputtering power. However, no saturation of magnetization ( Ms ) was visible for the thin film samples, indicating superparamagnetic behavior due to nanocrystallinity. The comparison of in-plane and out-of-plane magnetizations of the N-NFO film (both at 20 and 300 K) showed that the easy magnetization direction lied in the plane of the film. The optical transmission spectra revealed decrease of direct band gap with increase of sputtering power. [ABSTRACT FROM AUTHOR]

Presents a study which performed ferromagnetic resonance (FMR) on fine powders of Ho[sub0.85]Tb[sub0.15]Fe[sub2]H[subx] and Dy[sub0.73]Tb[sub0.27]Fe[sub2]H[subx] at X and Q bands. Investigations on the effect of hydrogen on the structural and magnetic properties of Ho[sub0.85]Tb[sub0.15]Fe[sub2]H[subx] and Dy[sub0.73]Tb[sub0.27]Fe[sub2]H[subx] systems; Description of the preparation of the samples and their characterization; Details on the FMR spectra of the samples.

Temperature dependence of magnetization, anisotropy, and hyperfine interaction parameters of NiFe2–xYbxO4 ( $x = 0$ , 0.05, and 0.075) was investigated, and the results are presented. All the compounds were prepared by solid-state reaction formed in cubic inverse spinel phase with the space group $Fd\overline 3 m$ . Increments in the lattice constant were observed upon partial substitution of Fe3+ by Yb3+. Decreased magnetic moment and increased magnetic anisotropy with Yb3+ substitution were observed through magnetization measurements, carried out at 5, 100, 200 and 300 K. Analyses of Mössbauer spectra recorded at 5 K and 300 K, revealed decreased hyperfine fields and magnetic moments at the B-site (and hence net moment) with increasing Yb3+ content. In addition all the compounds exhibited Neel-type, collinear ferrimagnetic structure. [ABSTRACT FROM PUBLISHER]

Structural, electrical, and magnetoreactance (mr) characteristics of rare Earth-doped Ni ferrite (NiO.Fe2-x RxO3(x = 0, 0.075, R = Dy, Gd), and NiO.Fe1.95R0.05O3(R, = Gd, Nd)) were investigated. All the materials formed in the cubic inverse spinel phase with small amounts of RFeO3 as the additional phase. mr was measured in both longitudinal and transverse configuration. A mr of - 1477% was observed for pure nickel ferrite at 10 kHz while it is smaller for the rare Earth-doped compounds. With increasing frequency maximum mr value is found to decrease. The resistivity was found to decrease with increasing frequency for all the compounds and dispersion of relaxation times was observed. [ABSTRACT FROM AUTHOR]

Alloys of Y1 − x Gd x Fe2B y ( x = 0, 0.25, 0.5, 0.75 and 1; y = 0, 0.1, 0.15 and 0.2) have been prepared and investigated for structural and magnetic properties. The compounds with x = 0 and 1 are found to form in single phase with C15-type cubic Laves phase structure, while those with x = 0.25, 0.5 and 0.75 are observed to form with small quantities of secondary (Y,Gd)Fe3 phase. The lattice parameters, Curie temperature and the average Fe hyperfine field are found to increase with increasing x. The Gd–Gd and Gd–Fe interactions are attributed to be the main reason for the enhancement of magnetic properties. Boron was found to stabilize the (Y,Gd)Fe2 phase without affecting the magnetic properties. [ABSTRACT FROM AUTHOR]

Structure and magnetostriction of TbxDy0.9-xNd0.1Fe1.93 (0.2≤x≤0.4) compounds are investigated. All the compounds are found to stabilize in MgCu2-type C15 cubic Laves phase structure. The easy magnetization direction changes from <100>(x=0.2) to <111>(x=0.3) through an intermediate state at x=0.25. Anisotropy compensation is realized near x=0.25 for the TbxDy0.9-xNd0.1Fe1.93 compounds. The Laves phase compound Tb0.4Dy0.5Nd0.1Fe1.93 has large spontaneous magnetostriction (1670×10-6) and a low anisotropy at room temperature which could make it a good candidate material for magnetostriction applications. [ABSTRACT FROM AUTHOR]

First-principles calculation has been carried out for the full Heusler alloy Co2FeGe within the scheme of density functional theory using plane-wave self-consistent field method. The spin polarized band structure does not show any energy gap at the Fermi level for both up and down spin electrons. Atom resolved magnetic moment on each site was observed to be 1.3 μB (Co), 2.9 μB (Fe), and 0.0 μB (Ge). X-ray diffraction studies reveal a B2-type structure for the bulk sample and cubic L21 structure for the melt-spun ribbons. The lattice parameter value for the ribbon is 5.736 Å, and its Curie temperature is around 981 K. The magnetic moment per formula unit at 5 K was observed to be 5.74 μB. The low temperature data (< 100 K) follows the relationρ = ρo + AT2 + BT4.5, indicating the presence of one magnon spin-flip scattering. [ABSTRACT FROM AUTHOR]

The magnetoelectric (100-x)BaTiO3–(x)NiFe1.98O4 (x=20, 40, 60, and 80 wt %) particulate composites have been prepared and the effects of size and interface are studied through microscopy measurements. Large magnetoelectric voltage coefficient (αE) values accompanied by large piezoelastic coefficient, large magnetostrictive strain coefficient, and an adequate interface contact between the magnetic and electric phases were observed in these nanocomposites. The nanocomposite with x=40 has an αE value of 252 mV cm-1 Oe-1, which is the largest value for any particulate magnetoelectric composite, based on the available open literature. [ABSTRACT FROM AUTHOR]

The Laves phase compound YCo2 is a well-known exchange-enhanced Pauli paramagnet. We report here that, in the nanocrystalline form, this compound interestingly is an itinerant ferromagnet at room temperature with a low coercive field. The magnitude of the saturation moment (about 1μB per formula unit) is large enough to infer that the ferromagnetism is not a surface phenomenon in these nanocrystallites. Since these ferromagnetic nanocrystallites are easy to synthesize with a stable form in air, one can explore applications, particularly where the hysteresis is a disadvantage. [ABSTRACT FROM AUTHOR]

A magnetostrictive transducer operating at 100 kHz using rare earth transition metal giant magnetostrictive material for nondestructive testing (NDT) applications was designed and fabricated. The giant magnetostrictive Tb0.3Dy0.7Fe2 material was chosen as the active element for the present purpose. From the impedance measurements, the resonant frequency of the transducer is found to be 100 kHz. The performance of the transducer was validated by carrying out NDT on a test concrete block with delaminated regions, using the ultrasonic through-transmission technique and the pitch-catch method. [ABSTRACT FROM AUTHOR]

The polycrystalline Sm1-xNdxFe1.93 (x=0, 0.08, 0.12, 0.16, 0.2, 0.24, 0.32, and 0.36) compounds are found to stabilize in MgCu2-type C15 cubic Laves phase structure. The compound x=0.12 is found to exhibit giant magnetostriction value of -1572×10-6 due to the anisotropy compensation between Sm3+ and Nd3+ ions. The easy direction of magnetization (EMD) is observed towards <111> for the 0≤x≤0.20 compounds, accompanied by a rhombohedral distortion. For the x=0.32 compound, an orthorhombic distortion, with a support that the EMD is towards <110>, is observed [ABSTRACT FROM AUTHOR]

Magnetic and electrical transport studies have been carried out on Ho0.85Tb0.15Fe2-xMnx [x = 0–2] in the temperature range 5-300 K. The saturation magnetization at 5 K is found to increase with increasing Mn content due to the absence of Mn moments. The temperature variation of magnetization reveals several spin reorientation transitions and these are compared with the ac susceptibility results. Electrical resisitvity reveals the dominance of electron magnon scattering at low temperatures and electron-phonon scattering at high temperatures. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of YGdFe17-xCox Ga (x = 0, 1, 2 and 3) have been investigated through X-ray diffraction and magnetization studies. All the compounds up to x = 0.2 are formed in a single-phase, hexagonal structure. The unit cell volume decreased with the addition of Co due to the smaller size of Co than that of Fe. The magnetization and Curie-temperature values are found to increase with the addition of x and could be due to the additional Co-Co, Fe-Co exchange whose magnitude is larger compared to that of Fe-Fe exchange. Magnetically aligned sample powders indicate the presence of planar anisotropy for all the compounds. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Co substituted (Sm0.4Pr0.6)3(Fe1-xCox)27.5Ti1.5 [x = 0.1,0.2,0.3,0.4] compounds have been studied through powder X-ray diffraction (XRD) and magnetization measurements. All the compounds have formed in monoclinic R3 (Fe,M)29 phase with A2/m space group. The unit cell volume decreases with Co concentration in accordance with its size. The magnetization at room temperature increases with Co substitution and is qualitatively explained on the basis of rigid band approximation. Curie temperature is also found to increase with Co concentration. XRD patterns on the magnetically oriented samples reveal that nearly axial anisotropy is obtained for the x = 0.4 compound and that the easy magnetization direction (EMD) is along [2 04]. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Gd3 (Fe1-xAIx)27.5Ti1.5 (0.1–0.4) have been investigated by X-ray diffraction (XRD), magnetization and Curie temperature (Tc) measurements. All the compounds have formed in Nd3 (Fe,Ti)29 (3:29) type structure with Gd(Fe,Ti)12 (1:12) phase as the secondary phase and traces of cr-Fe. The unit cell parameters increase anisotropically with the Al content. The saturation magnetization decreases with increasing Al and is attributed to the magntovolume effect and the modification of the density of states (DOS). The increase of Curie temperature up to x = 0.3 and subsequent decrease is explained on the basis of band narrowing. The easy direction of magnetization (EMD) is away from the ab-plane up to x = 0.3 changes to along ab-plane for x = 0.4. [ABSTRACT FROM AUTHOR]

Bulk materials of TbFe2 (giant magnetostrictive) and TbFe3 were prepared by arc melting the constituent high pure elements under argon atmosphere. The two materials together were ball milled in toluene atmosphere for 70 h. The mixture is found to be predominantly amorphous after about 37 h of milling. The saturation-magnetization initially was found to increase and then found to decrease with milling time. The anisotropy of the material is seen to decrease as the milling time was increased, due to the formation of the amorphous phase. Differential scanning calorimetry (DSC) studies on the powders milled for 70 h showed two phase transitions, one at 90 °C and another one at 110 °C. Powder X-ray diffraction (XRD) of the annealed sample showed that a metastable phase formed at 90 °C and is found to be TbFe5 phase and that the phase formed at 110 °C was TbFe3. The average particle size calculated using the Sherrer's formula is found to be 30 nm. [ABSTRACT FROM AUTHOR]

Presents a study which determined the anisotropy and first order magnetization processes in alloys of composition of samarium-praseodymium-iron-cobalt-titanium. Experimental procedure; Results and discussion; Conclusions.