In this paper, the effect of partial replacement of Nd by Dy atoms on the magneto-elastic properties of Nd2-x,DxFe14C (2-14-1 type) alloys with x = 0.1, 0.3 and 0.5, in a temperature range of 77 K to room temperature have been studied using MAGNETOSTRICTION measurement. The first Order Magnetic process, FOMP, was determined by measuring the temperature dependence of low field magnetic usceptibility. Results show that an indicative temperature for FOMP, Tsp, increases about 40 K with increasing Dy content, which can be due to the non-negligible role of the higher than second order terms (k4m, k6m, …) of the crystalline field anisotropy of the rare earth sub-lattice. This conclusion is confirmed via MAGNETOSTRICTION results, which show that the partial substitution of Dy for Nd increases the anisotropic MAGNETOSTRICTION. This is attributed to a stronger magneto- crystalline anisotropy. At T > Tsp, Dy partial substitution also causes an increase in the volume MAGNETOSTRICTION, which indicates a positive exchange magnetostrictive effect of Dy- Fe anti- ferromagnetic interaction.

Nickel doped CoMn ferrites with high magnetization were synthesized by double sintering solid state route with compositions of Co0.7-xNixMn0.3Fe2O4 with x = 0, 0.05, 0.1 and 0.15. Theoretical Cation distribution for cubic spinel ferrites was suggested on basis of electrical configuration expectations and cation site preferences. Cation distribution suggested was in good agreement with experimental results obtained from VSM and XRD. Values of theoretically calculated magnetic moment, coercivity and magnetization are in good agreement with experimental data obtained from VSM. Maximum saturation magnetization of 37.7emu/gm is obtained for sample Co0.7Mn0.3Fe2O4 at magnetic field of 5K Oe. MAGNETOSTRICTION was found to increase with increasing magnetic field (from 1KOe to 5KOe.) Maximum MAGNETOSTRICTION of 84ppm was observed for sample Co0.7Mn0.3Fe2O4 at 5KOe. Maximum magnetization of magnetoelectric composites with 30% Co0.7-xNixMn0.3Fe2O4 – 70% PbZr0.48Ti0.52 was found to be 7.4 emu/g for composition with x = 0.

In this research, the magnetic phase transition and anisotropic magnetoelastic effects of a polycrystalline sample of Ndl4Dy2Fe78sB6 were studied by susceptibility and MAGNETOSTRICTION measurements. The composition was prepared by casting method. SEM pictures and XRD analysis showed that it was composed of polycrystalline magnetic phases with the main phase of 2-14-1.Results of ac susceptibility measurements show that the sample undergoes a magnetic phase transition at about 130 K, which is due to a gradual spin reorientation accompanied with crystal structure distortion. MAGNETOSTRICTION measurements in three orthogonal directions of the main body of the sample were performed in the range of 77 K to 300 K and if the field up to 1.5 T. At temperatures below 125 K, the MAGNETOSTRICTION values in three orthogonal directions differ by a factor of two to three. This anisotropy in MAGNETOSTRICTION indicates preferential orientation of the crystalline grains in the volume of the sample. In addition, MAGNETOSTRICTION curves show minimum values near the phase transition temperature with different values in the different directions. Minimum values of MAGNETOSTRICTION can be explained by the critical behavior of the orbital magnetic moments of the Fe atoms at the phase transition temperature.

In this paper, a magnetostrictive material (MSM)-based energy harvesting device is proposed. The device is made up of a steel beam laminated with Metglas 2605sc as the magnetostrictive material, the device undergoes mechanical strain due to the external base excitation. The mechanical strain yields in a magnetic field around the beam. A pickup coil is surrounded around the beam which converts the magnetic field into electrical current. The equation of motion is derived based on the nonlinear Euler-Bernoulli beam theory to account for large deflections. Kirchhoff and Faraday's laws are also benefited to couple the mechanical, magnetic and electrical fields. The equation is discretized based on the Galerkin method and numerically integrated over time. Energy conservation is examined and the response in the frequency domain is obtained. In the case of initial displacement, in the absence of mechanical damping, vibration amplitude attenuates as the electrical current induces in the pickup coil, this was attributed to the attenuation of the total mechanical energy of the beam as it was harvested from the pickup coil. The temporal response was fitted to that of a single degree of freedom mass-spring-damped and the equivalent damping ratio was determined. The attenuation rate was studied with different values of resistance and the number of turns in the pickup coil and the relation between these two factors was obtained to maximize the output electrical power.

In this research the magnetoelastic properties of Nd6Fe13-xCoxCu (x=0 and 1) compound are investigated. Analysis of X-ray diffraction patterns indicates that a single phase is formed approximately for x=0 and the x=1 sample is multi-phase. The lattice parameters were decreased, the Néel temperature of main phase and the Curie temperature of impurity phase was increased with Co content. Due to the presence of Nd2Fe17-yCoy ferromagnetic phase in the sample with x=1 the change of the anisotropy and increase of exchange effects was observed in the magnetic and magnetoelastic measurements. Thermal expansion, longitudinal (ll) and transverse (lt) MAGNETOSTRICTION were measured using the strain gauge method in the selected temperatures range of 80- 500 K under applied magnetic fields up to 1.5 T. Anomaly and Invar effect are observed in the linear thermal expansion and a (T) curves at the Néel temperature. The linear spontaneous MAGNETOSTRICTION decreases sharply by approaching the Néel temperature and also shows the short-range magnetic ordering effects when antiferromagnetic to paramagnetic transition occurs. In the low field region, the absolute values of anisotropic MAGNETOSTRICTION of Nd6Fe13Cu compound are small and then start to increase with applied magnetic field. Each isofield curve of the anisotropic MAGNETOSTRICTION passes through a minimum and then approaches to zero with increasing temperature. This MAGNETOSTRICTION compensation arises from the difference in the magnetoelastic coupling constants of the sublattices in this compound.

In this research, MAGNETOSTRICTION and thermal expansion of polymer-bonded Nd4Fe77.5B18.5 nano-composites are studied using strain gage method. The effect of sintering on samples is also studied. X-ray diffraction patterns and SEM pictures of the original and annealed samples show that the grain size of α-Fe and Fe3B soft magnetic phases in amorphous matrix increases and mechanical hardness of the samples improves after annealing at 700 °C for 20 min.. Overall behavior of the thermal expansion is similar for samples in both cases, with about 20% larger coefficient for the annealed one. The MAGNETOSTRICTION measurements show huge magnitudes in order of 10-4 at the presence of relatively weak external magnetic fields. The magnitude of MAGNETOSTRICTION noticeably decreases after annealing which can originate from two different sources. MAGNETOSTRICTION of the original sample mainly originates from single particle interactions of Nd-sublattice in Nd2Fe14B phase, but the situation is very different for the annealed sample. The complicate variations of the magnetostrictive isotherms of the annealed sample are discussed based on the following three factors: internal stresses, magnetocrystalline anisotropy and mechanisms of coercivity.

In giant magnetostrictive transducer, Young modulus of the core considerably alters with changing its magnetic level. Young modulus change in Terfenol-D core has the highest value. This effect changes the resonance frequency and mode shapes of the transducer. This subject in Terfenol-D resonance transducer is studied in this paper. For this purpose, a resonance Terfenol-D transducer has been designed and fabricated. Node locations in the transducer are considered to add pre-load and bias mechanisms. Effect of Young modulus change on resonance frequency and mode shape were studied both analytically and by ANSYS FEM software. Range of resonance frequency change in the first mode is 1000 Hz and in the second mode is 100 HZ. Mode shapes changes are limited for both modes. In 40kA/m magnetic field bias, results from analytical and FEM simulation were verified with experimental results. Resonance frequency in this bias is 3100 Hz for the first mode and 8252 Hz for the second mode. Results have acceptable agreement with experimental results. Moreover, in this bias magnetic field, impedance responses between first and second modes are compared. Results show that selecting second mode is preferable for reducing disturbance of Young Modulus change on vibrational behavior.

In this work, the structural and magnetic properties of ingot and melt-spun Pr3Fe24.75Co2.75Ti1.5 compounds have been investigated. The structural characterization of the compounds, by X-ray powder diffraction, is evidenced for a monoclinic Nd3 (Fe, Ti) 29-type structure (A2/m space group). A 2-type FOMP have been observed in the magnetic AC susceptibility curves of the ingot and melt-spun compounds.MAGNETOSTRICTION and linear thermal expansion measurements have been performed by the standard strain gauge method in magnetic fields up to 1.5 T, and temperature range of 77 to 575 K. The calculated values of the ordering temperature, the room temperature saturation magnetization for the melt-spun Pr3Fe24.75Co2.75Ti1.5 compound are several times smaller than the corresponding values obtained in ingot Pr3Fe24.75Co2.75Ti1.5 compound. The above obtained results have explained the behavior of measured values of spontaneous volume, longitudinal and transverse MAGNETOSTRICTION.

Influence of the partial substitution of Co for Fe on the structural, magnetic and magnetoelastic properties of Nd6Fe13Cu compounds are investigated. Analysis of X-ray diffraction patterns indicates that the multi-phase sample is formed for all samples. Upon Co substitution, the second phase Nd2Fe17, Nd2Fe17-yCoy with 0<y<1 and Nd2Fe17-zCoz with 1<z<2 is formed in the samples with x=0, 1, 2, respectively so that the lattice parameters are decreased and the Curie temperature is increased. Due to the ferromagnetic phase Nd2Fe17-yCoy in sample with x=1, the change of the anisotropy and increase of exchange effects are observed. The effects of long-range magnetic ordering processes on Néel temperature clearly appear in the temperature dependence of the spontaneous MAGNETOSTRICTION. Longitudinal (ll) and transverse (lt) MAGNETOSTRICTIONs are measured to study the magnetoelastic behaviour of these compounds using a strain gauge method. In the low field region, magnetostrictive strains are small and then increase with increasing fields. Strong pining center of Nd atoms that creates large magnetocrystalline anisotropy prevents easy movement of domain walls. In the sample with x=0, the MAGNETOSTRICTION contribution from the rare earth sublattice (Nd) dominates at low temperature and the Fe sublattice contribution becomes increasingly important as temperature rises.

Cobalt-based amorphous alloys attracted the attention of many researchers to carry out fundamental research for their application in electronics, sensors and magnetic memory due to their special magnetic properties including close to zero MAGNETOSTRICTION, magnetic permeability and high saturation magnetization. The purpose of this study is the formation and evaluation of microstructure and magnetic properties of cobalt-based amorphous alloy produced by melt spinning and mechanical alloying. The final compositions produced by both methods were studied by scanning electron microscopy, X-ray diffraction and vibrating magnetoresistance. The results showed that compound produced by chill block melt spinning has a better magnetic properties.