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Chengbao Jiang - One of the best experts on this subject based on the ideXlab platform.
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tuning Magnetostriction of fe ga alloys via stress engineering
Journal of Alloys and Compounds, 2020Co-Authors: Si Lan, Hanqiu Jiang, Yang Ren, Sinan Liu, Chengbao JiangAbstract:Abstract Stress has a strong impact on the magnetization and Magnetostriction of magnetic materials due to the magneto-elastic coupling. It offers a clue to understand the 2–5 times enhancement on the Magnetostriction of Fe–Ga alloys with rare-earth elements doping. In this article, the stress states of melt-quenched and melt-spun (Fe0.83Ga0.17)100-xTbx (x = 0–0.47) alloys were measured by high energy X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) technique. The macroscopic residual and microscopic stress of different Tb doped alloys were deduced from the shift and broadening of diffraction peaks and the deviation of the identified 1st Fe–Fe and 2nd Ga–Ga bond length. Rietveld refinement confirmed that the dissolved Tb atoms can replace the Fe/Ga site while small-angle neutron scattering (SANS) showed the presence of Tb-rich nanoscale precipitates. The effect of external stress loading and Tb doping on magnetization and Magnetostriction of the modified Fe–Ga alloys was compared and discussed. We propose that the magnetization and Magnetostriction of Fe–Ga alloys can be controlled through stress engineering by manipulating the magnetic domain structure through chemical doping or mechanical loading.
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determination of bulk domain structure and magnetization processes in bcc ferromagnetic alloys analysis of Magnetostriction in f e 83 g a 17
Physical Review Materials, 2018Co-Authors: Rudolf Schaefer, J M D Coey, Chengbao JiangAbstract:The ground state of macroscopic samples of magnetically ordered materials is a domain state because of magnetostatic energy or entropy, yet we have limited experimental means for imaging the bulk domain structure and the magnetization process directly. The common methods available reveal the domains at the surface or in electron- or x-ray transparent lamellae, not those in the bulk. The magnetization curve just reflects the vector sum of the moments of all the domains in the sample, but Magnetostriction curves are more informative. They are strongly influenced by the domain structure in the unmagnetized state and its evolution during the magnetization process in an applied field. Here we report a method of determining the bulk domain structure in a cubic magnetostrictive material by combining magneto-optic Kerr microscopy with Magnetostriction and magnetization measurements on single crystals as a function of applied field. We analyze the Magnetostriction of $\mathrm{F}{\mathrm{e}}_{83}\mathrm{G}{\mathrm{a}}_{17}$ crystals in terms of a domain structure that is greatly influenced by sample shape and heat treatment. Saturation Magnetostriction measurements are used to determine the fraction of domains orientated along the three $\ensuremath{\langle}100\ensuremath{\rangle}$ axes in the initial state. Domain wall motion and rotation process have characteristic signatures in the Magnetostriction curves, including those associated with the $\mathrm{\ensuremath{\Delta}}E$ effect and domain rotation through a $\ensuremath{\langle}110\ensuremath{\rangle}$ auxetic direction.
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giant heterogeneous Magnetostriction in fe ga alloys effect of trace element doping
Acta Materialia, 2016Co-Authors: Chengbao Jiang, Jinghua Liu, Bin Wang, Huiping Duan, Hui Wang, Tianli Zhang, Jingmin Wang, Zaoli Zhang, P Stamenov, J M D CoeyAbstract:Abstract Enhanced Magnetostriction in iron-rich Fe–Ga alloys has been attributed to a heterogeneous nanostructure with tetragonal inclusions, although direct experimental evidence for their structure was lacking. Here we use transmission electron microscopy to show that melt-spun, (001) textured Fe83Ga17 ribbons contain 3 nm inclusions with c-axis Ga–Ga pairs aligned in a tetragonal L60-type structure; the induced tetragonality of the entire A2 matrix is observed directly by synchrotron X-ray diffraction. Trace doping with 0.2 atomic % nonmagnetic elements such as La or Pb increases the magnetocrystalline anisotropy and greatly enhances the Magnetostriction. Rare-earth dopants from La to Lu produce a quarter-shell variation of the magnetic anisotropy; the crystal field parameter A20 is determined to be −15 Ka0−2. The best trace dopants are the light rare earths Ce and Pr that give a transverse Magnetostriction of up to −800 ppm, as these elements soften the tetragonal modulus via their crystal field interaction. A new model is proposed to explain nanoheterogeneous Magnetostriction, where the Ga–Ga pairs remain fixed, but the tetragonal axis of the matrix can be realigned in a magnetic field by a series of small deformations of the A2 matrix. These results signal a new approach to creating highly-magnetostrictive materials.
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recrystallization texture evolution and Magnetostriction behavior of rolled fe81ga19 98b2 sheets during low to high temperature heat treatments
Journal of Materials Science, 2014Co-Authors: Chengbao JiangAbstract:In order to study the texture evolution and Magnetostriction behavior in the rolled Fe–Ga–B sheets during the heat treatments from low to high temperatures, (Fe81Ga19)98B2 sheets were prepared and investigated. The phase structure, recrystallization, grain size, texture evolution, and Magnetostriction behavior during the annealing from 525 to 1200 °C for 1–5 h were investigated using X-ray diffraction, electron backscattering diffraction, and standard strain-gauge measurements. Results indicated that the primary recrystallization temperature for 1-h annealing was found as 525–575 °C in (Fe81Ga19)98B2 sheets. Annealing the sample below 575 °C for 1 h, the release of rolling stress and increase of 〈100〉 η-fiber texture during the primary recrystallization jointly resulted in a rapid improvement in Magnetostriction. After annealed between 575 and 1100 °C for 1 h, the grains of the sheets underwent a normal growth, and the three (α-, γ- and η-fiber) types of textures kept an approximate balance, leading to a plateau of Magnetostriction around 75 ppm. When the abnormal grain growth proceeded above 1100 °C for 1 h, the proportion of η-fiber texture markedly increased, and the Magnetostriction was subsequently increased to 97 ppm. For longer annealing durations, the strong ideal cube texture (η-fiber) was firstly formed and then changed to undesired texture (γ-fiber), producing a corresponding Magnetostriction peak of 136 ppm at 2 h for the annealing at 1200 °C. The clear correlation among heat treatments, recrystallization, texture, and Magnetostriction provides an essential understanding for Fe–Ga–B alloy sheets.
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the stress dependence of Magnetostriction hysteresis in tbdyfe 110 oriented crystal
Journal of Applied Physics, 2011Co-Authors: Zhibin Wang, Jinghua Liu, Chengbao JiangAbstract:The Magnetostriction curves and minor loops of the TbDyFe [110] oriented crystal are tested under different compressive pre-stress from 0 to 120 MPa. It is observed that the Magnetostriction hysteresis first increases from about 33 Oe under 0 MPa, achieves the maximum of about 70 Oe under 30 MPa, and then decreases to about 16 Oe under 120 MPa (near disappearance) with an increase in the compressive pre-stress. By the theoretical simulation, it is found that upon increasing the compressive pre-stress the dominant energy changes from magnetocrystalline anisotropy energy to magnetoelastic energy. This leads to the domain rotation mode changing from irreversibility to reversibility and consequently results in the decrease of Magnetostriction hysteresis, which explains the experimental results very well.
J M D Coey - One of the best experts on this subject based on the ideXlab platform.
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determination of bulk domain structure and magnetization processes in bcc ferromagnetic alloys analysis of Magnetostriction in f e 83 g a 17
Physical Review Materials, 2018Co-Authors: Rudolf Schaefer, J M D Coey, Chengbao JiangAbstract:The ground state of macroscopic samples of magnetically ordered materials is a domain state because of magnetostatic energy or entropy, yet we have limited experimental means for imaging the bulk domain structure and the magnetization process directly. The common methods available reveal the domains at the surface or in electron- or x-ray transparent lamellae, not those in the bulk. The magnetization curve just reflects the vector sum of the moments of all the domains in the sample, but Magnetostriction curves are more informative. They are strongly influenced by the domain structure in the unmagnetized state and its evolution during the magnetization process in an applied field. Here we report a method of determining the bulk domain structure in a cubic magnetostrictive material by combining magneto-optic Kerr microscopy with Magnetostriction and magnetization measurements on single crystals as a function of applied field. We analyze the Magnetostriction of $\mathrm{F}{\mathrm{e}}_{83}\mathrm{G}{\mathrm{a}}_{17}$ crystals in terms of a domain structure that is greatly influenced by sample shape and heat treatment. Saturation Magnetostriction measurements are used to determine the fraction of domains orientated along the three $\ensuremath{\langle}100\ensuremath{\rangle}$ axes in the initial state. Domain wall motion and rotation process have characteristic signatures in the Magnetostriction curves, including those associated with the $\mathrm{\ensuremath{\Delta}}E$ effect and domain rotation through a $\ensuremath{\langle}110\ensuremath{\rangle}$ auxetic direction.
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giant heterogeneous Magnetostriction in fe ga alloys effect of trace element doping
Acta Materialia, 2016Co-Authors: Chengbao Jiang, Jinghua Liu, Bin Wang, Huiping Duan, Hui Wang, Tianli Zhang, Jingmin Wang, Zaoli Zhang, P Stamenov, J M D CoeyAbstract:Abstract Enhanced Magnetostriction in iron-rich Fe–Ga alloys has been attributed to a heterogeneous nanostructure with tetragonal inclusions, although direct experimental evidence for their structure was lacking. Here we use transmission electron microscopy to show that melt-spun, (001) textured Fe83Ga17 ribbons contain 3 nm inclusions with c-axis Ga–Ga pairs aligned in a tetragonal L60-type structure; the induced tetragonality of the entire A2 matrix is observed directly by synchrotron X-ray diffraction. Trace doping with 0.2 atomic % nonmagnetic elements such as La or Pb increases the magnetocrystalline anisotropy and greatly enhances the Magnetostriction. Rare-earth dopants from La to Lu produce a quarter-shell variation of the magnetic anisotropy; the crystal field parameter A20 is determined to be −15 Ka0−2. The best trace dopants are the light rare earths Ce and Pr that give a transverse Magnetostriction of up to −800 ppm, as these elements soften the tetragonal modulus via their crystal field interaction. A new model is proposed to explain nanoheterogeneous Magnetostriction, where the Ga–Ga pairs remain fixed, but the tetragonal axis of the matrix can be realigned in a magnetic field by a series of small deformations of the A2 matrix. These results signal a new approach to creating highly-magnetostrictive materials.
Masato Enokizono - One of the best experts on this subject based on the ideXlab platform.
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Influence of Biaxial Stress on Vector Magnetic Properties and 2-D Magnetostriction of a Nonoriented Electrical Steel Sheet Under Alternating Magnetic Flux Conditions
IEEE Transactions on Magnetics, 2014Co-Authors: Yuichiro Kai, Takashi Todaka, Yuji Tsuchida, Masato EnokizonoAbstract:Magnetic properties of nonoriented electrical steel sheets are influenced by mechanical stress because they exhibit the phenomenon of Magnetostriction. Therefore, it is necessary to clarify the relationship between magnetic properties and Magnetostriction under mechanical stress. This paper presents the results of measurements of the vector magnetic properties and the Magnetostriction of a nonoriented electrical steel sheet under biaxial stress. The loci of the magnetic field strength vector and the 2-D Magnetostriction are measured under both biaxial stresses. The magnetic power loss and the peak-to-peak value of the Magnetostriction in an arbitrary direction decreased due to the applied biaxial tensile stress. It can be concluded that it is possible to improve the magnetic properties and reduce the Magnetostriction of an electrical steel sheet by applying biaxial tensile stress.
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three dimensional Magnetostriction and vector magnetic properties under alternating magnetic flux conditions in arbitrary direction
Electrical Engineering in Japan, 2012Co-Authors: Daisuke Wakabayashi, Takashi Todaka, Masato EnokizonoAbstract:This paper presents the measured Magnetostriction of electrical steel sheets under alternating magnetic flux conditions. In the measurements, we used a two-dimensional vector magnetic property measurement system, and a three-axial strain gauge. In order to know the Magnetostriction in an arbitrary direction, the strain tensor was evaluated. In addition, we try to evaluate the Magnetostrictions in the thickness direction. In this paper, the three-dimensional Magnetostriction in nonoriented and grain-oriented silicon steel sheets are compared. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(4): 1–9, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21257
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development of a new strain gage for measurements of two dimensional Magnetostriction
Journal of Magnetism and Magnetic Materials, 1999Co-Authors: Masato Enokizono, K Takahashi, Y YamauraAbstract:Abstract Magnetostrictions occurring in ferromagnetic materials under alternating flux conditions can be measured by using strain gages, however, unnecessary voltages are also induced in the common gages due to fluctuating outer magnetic field. To solve the problem, we developed a new strain gage that could remove the influence of the outer magnetic field and applied it to measuring two-dimensional Magnetostrictions. The results show that the new gage is very useful in the accurate measurement of the Magnetostrictions under rotating magnetic field conditions.
S Pascarelli - One of the best experts on this subject based on the ideXlab platform.
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atomic scale mechanisms for Magnetostriction in cof e 2 o 4 and l a 0 5 s r 0 5 co o 3 oxides determined by differential x ray absorption spectroscopy
Physical Review B, 2019Co-Authors: G Subias, Vera Cuartero, Joaquin Garcia, Javier Blasco, S PascarelliAbstract:The atomic environments involved in the Magnetostriction effect in $\mathrm{CoF}{\mathrm{e}}_{2}{\mathrm{O}}_{4}$ and $\mathrm{L}{\mathrm{a}}_{0.5}\mathrm{S}{\mathrm{r}}_{0.5}\mathrm{Co}{\mathrm{O}}_{3}$ polycrystalline samples have been identified by differential extended x-ray absorption fine structure (DiffEXAFS) spectroscopy. We demonstrate that cobalt atoms at octahedral sites are responsible for their Magnetostriction. The analysis of DiffEXAFS data indicates that the local-site magnetostrictive strains of Co atoms are reversed in these two oxides, in agreement with the macroscopic Magnetostriction. For the $\mathrm{CoF}{\mathrm{e}}_{2}{\mathrm{O}}_{4}$ spinel, a large negative strain along the (100) direction has been determined for the $\mathrm{Co}{\mathrm{O}}_{6}$ octahedron causing a tetragonal contraction in contrast with the $\mathrm{L}{\mathrm{a}}_{0.5}\mathrm{S}{\mathrm{r}}_{0.5}\mathrm{Co}{\mathrm{O}}_{3}$ perovskite, where a positive moderate strain along the (100) direction was found resulting in a tetragonal expansion. The different local-site Magnetostriction is understood in terms of the different valence and spin state of the Co atoms for the two oxides. The macroscopic Magnetostriction would be explained then by the relative change in volume, either contraction in $\mathrm{CoF}{\mathrm{e}}_{2}{\mathrm{O}}_{4}$ or expansion in $\mathrm{L}{\mathrm{a}}_{0.5}\mathrm{S}{\mathrm{r}}_{0.5}\mathrm{Co}{\mathrm{O}}_{3}$, when the tetragonal axis of the Co site is reoriented under an externally applied magnetic field.
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direct measurement of intrinsic atomic scale Magnetostriction
Physical Review Letters, 2008Co-Authors: M P Ruffoni, Cristina Bormionunes, Sato R Turtelli, R. Grössinger, S Pascarelli, R F PettiferAbstract:Using differential x-ray absorption spectroscopy (DiffXAS) we have measured and quantified the intrinsic, atomic-scale Magnetostriction of Fe81Ga19. By exploiting the chemical selectivity of DiffXAS, the Fe and Ga local environments have been assessed individually. The enhanced Magnetostriction induced by the addition of Ga to Fe was found to originate from the Ga environment, where lambda(gamma,2)(approximate to (3/2)lambda(100)) is 390 +/- 40 ppm. In this environment, Ga-Ga pair defects were found to exist, which mediate the Magnetostriction by inducing large strains in the surrounding Ga-Fe bonds. For the first time, intrinsic, chemically selective magnetostrictive strain has been measured and quantified at the atomic level, allowing true comparison with theory.
P A Joy - One of the best experts on this subject based on the ideXlab platform.
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high Magnetostriction coefficient of mn substituted cobalt ferrite sintered from nanocrystalline powders and after magnetic field annealing
Current Applied Physics, 2013Co-Authors: Khaja K Mohaideen, P A JoyAbstract:Magnetostriction characteristics of Mn substituted cobalt ferrite, CoFe2−xMnxO4 (0 ≤ x ≤ 0.3), sintered from nanocrystalline powders of average particle size of ∼4 nm have been studied. Larger value of Magnetostriction at lower magnetic field is achieved after substitution of Mn for Fe. The maximum value of Magnetostriction coefficient is not much affected and the slope of the Magnetostriction is increased with increasing Mn content. Higher maximum value of Magnetostriction coefficient (λ) of 234 ppm comparable to that of the unsubstituted composition with larger strain derivative (dλ/dH) is obtained for x = 0.2 in CoFe2−xMnxO4. The Magnetostriction coefficient is increased to 262 ppm with further enhancement in the strain derivative after annealing the sintered compact at 300 °C in a magnetic field of 400 kA/m for 30 min.
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high Magnetostriction and coupling coefficient for sintered cobalt ferrite derived from superparamagnetic nanoparticles
Applied Physics Letters, 2012Co-Authors: Khaja K Mohaideen, P A JoyAbstract:High Magnetostriction (λ) and coupling coefficient (dλ/dH) of 315 ppm and 1.97×10−9 A−1m, respectively, are obtained at room temperature for sintered cobalt ferrite derived from nanocrystalline powders. Also, the powder was compacted at a low pressure of 8 MPa and sintered for a short duration of 10 min at 1450 °C. Magnetic annealing at 300 °C in a field of 0.5 T for 30 min further enhanced the Magnetostriction coefficient to 345 ppm with a higher coupling coefficient 2.12×10−9 A−1m. The magnetic field above which maximum Magnetostriction is observed is reduced by almost half after magnetic annealing.
