Hysteresis Parameters Research Articles

Temperature-dependent dynamic hysteresis scaling of ferroelectric hysteresis parameters of lead free [(Ba0.825+xCa0.175−x)(Ti1−xSnx)O3]ceramics

Present article presents ferroelectric hysteresis behavior of [(Ba0.825+x Ca0.175−x)(Ti1−xSnx)O3] ceramics for x = 0.0625, 0.0875 and 0.100 samples. Temperature-dependent ferroelectric hysteresis scaling affiliation for remnant polarization (Pr) and coercive field (Ec) have been recommended. In view of scaling, the power law temperature proponent was efficiently settled for the hysteresis parameters. The dynamic hysteresis scaling of Pr and Ec at sintering temperature of 1450 °C for 2 h harvest Pr α T−0.92and Ec α T−038. By Arrhenius law, the back switching polarization (Pbc) and domain dynamics also evaluated in the form of temperature (T).

A Simple Technique to Evaluate Hysteresis Parameters of Small Ferrite Samples

A novel simple technique to evaluate hysteresis parameters of miniature ferrite objects is presented. It is based on simultaneously applied sawtooth bias field and a low-intensity harmonic electromagnetic modulation signal of a few megahertz to magnetize a ferrite. An appearance of the output signal at the harmonics of the RF modulation frequency, when the bias field passes the hysteresis inflection points, allows for measuring the saturation magnetization. Also, in ferrite monocrystals, it is possible to evaluate the effective crystallographic anisotropy. Some experimental results are presented.

Significant pedogenic and palaeoenvironmental changes during the early Middle Pleistocene in Central Europe

Three well-developed paleosols from the Paks loess succession (Hungary), a key profile of the European Loess Belt, were sampled and studied by rock magnetic methods, such as low-field magnetic susceptibility and hysteresis measurements. The studied paleosols formed in MIS19, MIS15 and MIS11 and represent key periods in the Middle Pleistocene, namely, the Middle Pleistocene transition (MPT) (MIS19), and frame the mid-Brunhes transition (MIS15 and 11).The results of the low-field magnetic susceptibility measurements, a popular interglacial intensity proxy, showed different patterns and values. The different characteristics of the susceptibility curve indicate different degrees of pedogenesis and therefore different soil-forming palaeoenvironments. The comparison of the rock magnetic (hysteresis) parameters supports the results of the susceptibility measurements and revealed some components of two characteristic palaeoclimate types: i.) a humid and warm MIS19 (pre-)MPT interglacial environment with very intense weathering and pedogenesis and ii.) a moderate climate with seasonal precipitation in a post-MPT interglacial environment during MIS15 and MIS11 characterized by intense but different types of pedogenesis compared to MIS19. This result, compared with other loess successions in the Middle and Lower Danube Basin and the western part of the East European Plain, helps to improve the climate model regarding the changing of the characteristic palaeoenvironment from a sub-Mediterranean (in the south) and temperate and humid climate (with forests, in the north) towards a cooler grassland/forest steppe-ruled environment in the region.

Characterization of Volcanic Ash From the 2017 Agung Eruption, Bali, Indonesia

In 2017, Mount Agung in Bali, Indonesia erupted after 54 years of dormancy. This eruption produced large amount of ash causing disruptions in this major tourist destination. Scientifically, however, this eruption produced important research material (volcanic ash). In this study, volcanic ash samples from 2017 Mount Agung eruption is subjected to geochemical and magnetic analyses, to gather information regarding the magmatic processes beneath Mount Agung. Samples were collected from four locations of varying distances. Magnetic analyses include measurement of magnetic susceptibility and hysteresis parameters, while geochemical analyses were carried out to determine the composition of major elements. These analyses are supplemented by petrographic analyses. Preliminary results show that the magnetic susceptibility values of the samples vary from 778 to 1002 × 10−8 m3/kg, the grain type is non-SP until the SP and non-SP grain mixtured, and the magnetic domain is the PSD and SP which differ significantly different from that of volcanic ash samples from other volcanos (Kelud, Sinabung, Soputan, Bromo, Merapi, Slamet) reported by previous studies. The results signify the potential use of rock magnetic methods combined with geochemical and petrographic analyses in characterizing volcanic ash.

Multimethod Characterization of Volcanic Ashes from The Sunda Island Arc

Compared to other countries in the world, Indonesia has the highest number of volcanoes; many of these volcanoes are located in the Sunda Island Arc. Considering their importance’s as geological markers, identification of the sources of volcanic ashes is challenging and intriguing task. Standing on that reason, this study was aimed to characterize the magnetic and geochemical properties of several volcanic ashes from Sunda Island Arc to test whether these properties could serve as identifiers for the sources. This study used the ashes from Mount Sirung (in Pantar) and from Mounts Merapi and Slamet (in Java). The data would then be combined and compared with previous studies that used ashes from other volcanoes both inside as well as outside the Sunda Island Arc. The results showed that the magnetic susceptibility of Mounts Merapi and Slamet differed not too much, while that of Mount Sirung differed significantly due to low magnetic content. The plot of hysteresis parameters classified Mount Merapi into PSD domain and Mount Slamet into SP domain, while that of Mount Sirung could not be performed due to the weak signal obtained. Geochemical data also showed that ashes from Mount Sirung contained much lower concentration of Na2O + K2O compared to that in Mounts Merapi and Slamet. Each volcano had its distinct magnetic properties when these properties were compared to that of other volcanoes previously studied. The geochemical data also could reflect its magma properties regarding to its geological setting. It could be concluded that these multimethod approaches were able to differentiate volcanic ashes based on their sources.

An Open-Circuit Method to Control the Hysteresis Parameters of Rare-Earth Permanent Magnets

Abstract—The peculiarities of application of the open-circuit method and prospects for development of technological equipment for monitoring the hysteresis parameters of permanent magnets from highly coercive hard magnetic material have been considered using complex-shaped samples in the pulse magnetic field. The advantages of the open magnetic circuit method and problems that occur during the development of technological equipment have been shown. Based on an analysis of foreign and domestic publications, it has been concluded that the direction is promising. The information on design features, characteristics of the developed equipment for processing control over permanent magnets from hard magnetic materials have been presented.

The Mechanical Interpretation of Ocular Response Analyzer Parameters.

Purpose Ocular Response Analyzer (ORA) is one of the most widely used devices in clinic, while the mechanical interpretations of parameters obtained from ORA have not been understood completely. The aim of this research is to explore the mechanical interpretation of ORA parameters. Methods Rabbits aged 3-24 months were measured with ORA in vivo and corneal strips uniaxial tensile tests to get ORA parameters and corneal biomechanical parameters (corneal elastic modulus, relaxation time, and relaxation limit). The mechanical interpretation of ORA parameters was cognized preliminarily by analyzing the correlation between ORA parameters and corneal biomechanical parameters. On the other hand, finite element method was applied to simulate ORA measurements with different corneal biomechanical parameters to obtain quantitative relationship between ORA parameters and corneal biomechanical parameters further. Results Biomechanical experimental results showed that Corneal Resistance Factor (CRF) was correlated with corneal elastic modulus and relaxation limit significantly, while the significant correlations between Corneal Hysteresis (CH) and corneal biomechanical parameters were not observed. Results of finite element analysis showed that both CH and CRF were correlated with corneal elastic modulus, relaxation limit, and relaxation time significantly. Besides, corneal elastic modulus was positively correlated with upslop1 and upslop2 and negatively correlated with w2. Conclusions For all ORA parameters, CH, CRF, the upslope, and the width of the peaks are parameters which may reflect corneal elastic properties. It is viable to cognize mechanical interpretation of ORA parameters by the comparisons of the data from ORA and biomechanical tests of rabbits with different ages and the simulations of ORA based on finite element methods. Further studies are needed to confirm the mechanical interpretation.

Investigation of structural, hysteresis and electromagnetic parameters for microwave absorption application in doped Ba–Sr hexagonal ferrites at X-band

M-type Ba0.5Sr0.5CoxLaxFe12-2xO19 hexagonal ferrite has been synthesized by the conventional ceramic method. X-ray diffraction analysis confirmed formation of M-type hexagonal structure while scanning electron microscopy analysis revealed a reduction in grain size with the doping of Co2+ and La3+ ions. The electromagnetic/microwave absorption has been measured from 8.2 GHz to 12.4 GHz in the microwave frequency regime and substantiated through hysteresis parameters, quarter wavelength, impedance matching, loss mechanisms. The hysteresis parameters, derived from hysteresis loops, infer soft ferrite nature of compositions. The doping of Co2+ and La3+ decreases coercivity to 17 Oe in composition x = 0.2 and increases saturation magnetization to 74.2 emu/g in composition x = 1.0. The doping improves impedance matching and increases microwave absorption as well as absorption bandwidth in the prepared compositions. The pronounced multi-peaks of absorption have been observed in composition x = 0.2 and 0.4 in the investigated frequency region. The depicted reflection loss dips are tunable through doping and thickness of the compositions. The reflection loss increases to −43.33 dB in composition x = 0.2 at 10.75 GHz and 1.9 mm thickness. The composition x = 0.2 also shows −10 dB and −20 dB narrow absorption bandwidth of 300 MHz and 320 MHz respectively.

An Empirical Formulation for the Damping Ratio of Shape Memory Alloy for Base-Isolated Structures

Shape Memory Alloys (SMAs) are now widely used as a damping element into the isolation systems. The pre-stressed SMAs exhibit hysteretic damping through a nonlinear flag-shaped hysteresis loop. Many nonlinear models of the SMA are available to depict such behavior. The nonlinear models require a lot of effort and computational time for the analysis of base-isolated structures. Therefore, the codes recommend that a nonlinear model can be replaced by an equivalent linear model in the analysis. Linearization is a method to convert the nonlinearity of a system into a system with analogues linear parameters. This paper proposes an empirical equation for a damping ratio to get a linear damping coefficient of the SMAs which can be used in the seismic analysis of base-isolated structures. The evaluation of any damping ratio using the traditional system identification method does not give precise solutions due to variation in hysteretic parameters and the unpredictable nature of an earthquake. The empirical equation is proposed using a set of optimal statistical data obtained from the seismic analysis of a base isolated structure. Moreover, analysis of the base isolated structure using the newly modified equivalent elastic-viscous SMA model gives comparable and conservative results with a nonlinear SMA model as compared to the existing elastic-viscous SMA model. Since the hysteresis parameters are used to derive the empirical equation for the damping ratio, this equation is also applicable for any type of structure.

AF demagnetization and ARM acquisition at elevated temperatures in natural titanomagnetite bearing rocks

SUMMARY Understanding the temporal changes of the Earth’s magnetic field intensity is one of the main goals of modern palaeomagnetism. For most palaeointensity methods to yield reliable results, the magnetic minerals must obey a set of rules. One of these rules is the additivity of partial thermal (TRM) or anhysteretic remanent magnetizations (ARM). Additivity was previously shown for partial TRM in single-domain particles and more generally for ARMs. Additivity between these two low-field remanences, however, has not been investigated, yet. This paper presents a series of rock magnetic experiments on natural low Ti titanomagnetites (Curie temperature between 534 °C and 561 °C) examining the effects of high temperatures on alternating field (AF) demagnetization and acquisition of an ARM. One of our sample sets comes from a borehole drilled through the impact melt sheet of the Manicouagan crater (Canada), the other from the Rocche Rosse lava flow on the island of Lipari (Italy). Hysteresis parameters indicate the magnetic carriers in the pseudo-single-domain range showing no evidence for oxidation. Thermal demagnetization at 300 °C and 500 °C before AF demagnetization shifts the coercivity spectra towards higher fields. AF demagnetization experiments at 500 °C show a significant (by a factor between 1.4 and >7.6) reduction in median destructive field and a shift towards lower coercivities. A linear relationship was found between the peak magnetic field required to demagnetize a fraction of a full TRM of a sample at a specific temperature and the one necessary to demagnetize the same fraction at room temperature after heating to that temperature. The comparison of full ARM and partial TRM at successively higher temperatures with a hybrid hTARM reveals that combined additivity between the two kinds of remanences is fulfilled. These results open the possibility to demagnetize highly coercive minerals, such as hematite and goethite, which is often not achievable at elevated temperatures. Furthermore, the additivity of TRM and ARM remanences may be used to develop novel hybrid TRM/ARM palaeointensity methods for samples, where heating is problematic (e.g. in meteorites).

Effect of cobalt substitution on physical & electro-magnetic properties of SrAl4Fe8O19 hexa-ferrite

Cobalt substituted strontium hexa-ferrite (SrAl4Fe8-xCoxO19 where, x = 0, 0.2, 0.4, 0.6, 0.8, 1) were successfully prepared by sol-gel auto combustion synthesis method. The autocatalytic nature of the combustion process was studied by thermal analysis of the dried gels. The ferrite was characterized with respect to phase identification using X-ray diffraction. Saturation magnetization and hysteresis parameters were measured at room temperature with a maximum magnetic field of 70 kOe. As the cobalt concentration increased, the saturation magnetization was increased from 12.25 to 18.77 emu/gm, however, the coercivity decreased with the increase in cobalt concentration due to the spin canted structure was formed. The variation in the dielectric constant and dielectric loss factor were discussed in the frequency range of 20 Hz–20MHz. It was found that the dielectric constant & loss increased with the increase in Co content. The AC electrical resistivity was decreased with the increase of dopent concentration.

Extraction of hysteresis parameters in foil magnetostrictive composites

The work discusses the extraction of the uncommon hysteresis parameters as a function of the magnetization, M and magnetic field, H using low-field resonance principles to characterize foil magnetostrictive composites. Linear magnetizing process is derived as hysteresis lag, because the magnetic field lines generated by current flowing on the inductive winding are vector deviated. A series RLC circuit is employed here to evaluate hysteresis lag, where its equivalent voltage signals are inputs to a XY graph to obtain the hysteresis cycle as M-H loop in an oscilloscope screen. To validate the feasibility of the extraction of such those hysteresis parameters, bulk Mn-Zn ferrites were cut in foils to be evaluated by physical equations defined here. Hence, the conduction parameters estimated using M-H loops show as structure ordering of magnetostrictive composites is dependent on magnetic properties in the small-scale structures.

Implementation and Identification of Preisach Parameters: Comparison Between Genetic Algorithm, Particle Swarm Optimization, and Levenberg–Marquardt Algorithm

Electromagnetic simulations of devices with soft materials and the study of the influence of cutting edge deformations/stresses on the degradation of magnetic performances require the identification of hysteresis parameters. Hence, computationally efficient implementation and identification of the hysteresis model is needed to obtain a solution with high accuracy within a reasonable time. Many studies on hysteresis identification have been reported, but few compare different methods to identify the optimal one. In the present study, we focus on the Preisach hysteresis model combined with the Lorentz modified distribution function to describe the magnetic behavior of a fully processed nonoriented Fe–3wt% Si steel sheet under static excitation. Three different identification techniques are implemented and evaluated: particle swarm optimization (PSO), genetic algorithms (GAs), and nonlinear least-squares approximation based on the Levenberg–Marquardt (LM) method. We evaluate each approach with regard to the accuracy, central processing unit computation time, and repeatability of the results. All the techniques perform well in this high-nonlinearity problem. The root-mean-square error is < 3%. However, the implementation of the GA is more complex than the PSO and LM methods. The optimized parameters are obtained in a few minutes in the case of the LM method, but a few hours are required for both the other techniques. Therefore, the LM method is the most suitable technique for the identification of Preisach hysteresis.

Theoretical and experimental investigation of the particle size distribution and magnetic properties of the PP + FE3O4 nanocomposites

A detailed study of the dispersion of magnetite (Fe3O4) nanoparticles in the polypropylene (PP) matrix, the degree of coagulation, and the dependence of magnetic properties of PP + Fe3O4 nanocomposites on the size of nanoparticles is reported. The size distribution of nanoparticles in polymer matrix and morphology of the nanocomposites were studied by the means of scanning electron microscope (JEOL JSM-7600 F) and atomic force microscopy (NT-MDT). It was found that when the Fe3O4 nanoparticles are introduced into the PP matrix, their coagulation takes place. The increase in the size of the Fe3O4 nanoparticles depends on their volume content in the polymer matrix, the viscosity of polymer, mixing time, and so on. The magnetic properties of PP + Fe3O4 nanocomposites were experimentally and theoretically studied. It was found that the magnetic hysteresis parameters of the nanocomposites directly depend on the size and concentration of the Fe3O4 nanoparticles in the matrix. Theoretical calculations were compared with experimental results obtained from M( H) measurements. Discrepancy between theoretical and experimental magnetic values have been explained.

Hysteresis losses in nanocrystalline alloys with magnetic-field-induced anisotropy

Abstract The hysteresis losses and their relation to the parameters of the minor static hysteresis loops were investigated in the nanocrystalline Fe67.5Co5Cu1Nb2Mo1.5Si14B9 alloy with magnetic-field-induced anisotropy. The analysis of experimental data was performed using a power function, which approximated the dependencies between the hysteresis parameters. It is shown that all the experimental dependences in cores with magnetic-field-induced anisotropy in a weak magnetic field are consistent with the formulas derived from the Rayleigh law. It is also shown, that in a nanocrystalline alloy with uniaxial induced anisotropy, certain empirical relationships obtained earlier for isotropic materials are not met, particularly, for the relation of the hysteresis losses to the remanence and the maximal magnetic induction. It has been found, that samples with longitudinal induced anisotropy demonstrate low initial permeability, and the magnetization process in the Rayleigh region is carried out by the domain walls’ displacement at distances comparable to the correlation length Lex. A magnetic hysteresis mechanism associated with the irreversible magnetization rotation in ferromagnetic clusters of nanocrystalline alloys is proposed. Formulas are proposed to calculate hysteresis losses in a soft magnetic nanocrystalline material with a different magnetic anisotropy.

Particle Size Specific Magnetic Properties Across the Norwegian‐Greenland Seas: Insights Into the Influence of Sediment Source and Texture on Bulk Magnetic Records

AbstractWe make fundamental observations of the particle size variability of magnetic properties from 71 core tops that span the southern Greenland and Norwegian Seas. These data provide the first detailed regional characterization of how bulk magnetic properties vary with sediment texture, sediment source, and sediment transport. Magnetic susceptibility (MS) and hysteresis parameters were measured on the bulk sediment and the five constituent sediment particle size fractions (clay, fine silt, medium silt, coarse silt, and sand). The median MS value of the medium silt size fraction is ~3–5 times higher than that of the sand and clay size fractions and results in a strong sensitivity of bulk MS to sediment texture. Hysteresis properties of the clay size fraction are relatively homogeneous and contrast that silt and sand size fractions which show regional differences across the study area. These coarser fractions are more transport limited and using medium silt hysteresis measurements and low temperature MS behavior we establish three endmembers that effectively explain the variability observed across the region. We model the response of bulk magnetic properties to changes in sediment texture and suggest that variations in sediment source are required to explain the bulk magnetic property variability observed in cores across the southern Greenland and Norwegian Seas. These findings imply that sediment source has a greater influence on driving bulk magnetic property variability across this region than has previously been assumed.

An Efficient Identification Method for Dynamic Systems With Coupled Hysteresis and Linear Dynamics: Application to Piezoelectric-Actuated Nanopositioning Stages

The coupling between hysteresis and linear dynamics remains a challenge for modeling and control of piezo-actuated nanopositioning stages. A decoupling identification approach is proposed in this paper. The system is first modeled by a Bouc–Wen hysteresis model cascading a linear dynamic part. Then, a proposed direct integration method with high computational efficiency is used for the identification of the Bouc–Wen model. With the identified hysteresis parameters, a harmonic linearization method is subsequently used to estimate the actual input to the linear dynamics. Experiment results on a two degree-of-freedom nanopositioning stage demonstrate that both the rate-dependence and amplitude-dependence resulted from the coupling between the hysteresis and linear dynamics can be well predicted by the proposed approach. Compared with existing methods, the proposed approach shows advantages in terms of both model accuracy and identification efficiency.

Rock-magnetic and color characteristics of archaeological samples from burnt clay from destructions and ceramics in relation to their firing temperature

Determination of ancient firing temperatures of archaeological pottery is a widely discussed topic in archaeometry. Here, a set of magnetic characteristics (magnetic susceptibility, isothermal and anhysteretic remanences, hysteresis parameters) and color parameters were studied for a collection of pottery fragments and burnt clay from house destructions. The results show that magnetite and hematite of superparamagnetic to single domain grain size are the main iron oxides produced during heating. Hematite fraction is more important and frequently detected in pottery sherds than in burnt clay from destructions. An inverse linear regression was obtained between the estimated firing temperature and the ratio value/chroma, which is shown to be site specific for pottery samples. For burnt house destructions, the regression is less well constrained and most probably reflects differences in the raw material. Consideration of rock-magnetic parameters against firing temperature estimates reveals a direct link between saturation magnetization and ancient firing temperature for burnt clay from house destructions. In contrast, this link is inverse and worse defined for pottery materials. This different behavior is attributed to different prevailing processes of iron oxide transformations in burnt clay and pottery, related to the specific firing conditions.

Enhanced structural and magnetic properties of microwave sintered Li–Ni–Co ferrites prepared by sol–gel method

The properties of lithium ferrites are very sensitive to chemical composition, synthesis method, and sintering techniques. Li–Ni–Co ferrites with compositional formula , where in steps of 0.02 were prepared by chemical sol–gel method and sintered by microwave sintering technique. The x-ray diffraction patterns confirmed the formation of single phase with spinel structure in all the samples. The structural parameter viz. lattice constant, crystallite size, and x-ray density for these samples were studied and compared with those measured from samples of similar composition prepared by the sol–gel method and sintered by conventional sintering technique. Enhancement in the magnetic properties like Curie temperature, hysteresis parameters was observed by employing sol–gel synthesis combined with microwave sintering. The results obtained and mechanisms involved are discussed in the paper.

Magnetic characterisation of magnetite and hematite from the Blötberget apatite – iron oxide deposits (Bergslagen), south-central Sweden

Rock magnetic measurements were carried out on drill core material and hand specimens from the Blötberget apatite – iron oxide deposit in the Bergslagen ore province, south-central Sweden, to characterise their magnetic properties. Measurements included several kinds of magnetic susceptibility and hysteresis parameters. Petrographic and scanning electron microscopy were used to independently identify and quantify the amount and type of magnetite and hematite. Two hematite-rich samples were studied with laser ablation inductively coupled plasma mass spectrometry to quantify the trace element chemistry in hematite and investigate the potential influence of trace elements on magnetic properties. Three aspects of this study are noteworthy. (1) Hematite-rich samples display strong anisotropy of magnetic susceptibility, which is likely to affect the appearance and modelling of magnetic anomalies. (2) The magnitude-drop in susceptibility across Curie and Néel temperature transitions shows significant correlation with the respective weight percentage of magnetite and hematite. Temperature-dependent magnetic susceptibility measurements can therefore be used to infer the amounts of both magnetite and hematite. (3) Observations of a strongly depressed Morin transition at approximately −60 to −70 °C (200 to 210 K) are made during low-temperature susceptibility measurements. This anomalous Morin transition is most likely related to trace amounts of V and Ti that substitute for Fe in the hematite. When taken together, these magnetic observations improve the understanding of the magnetic anomaly signature of the Blötberget apatite – iron oxide deposits and may potentially be utilised in a broader context when assessing similar (Paleoproterozoic) apatite – iron oxide systems.