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Full-Text Articles in Physics

Effects Of Zn Additions To Highly Magnetoelastic Fega Alloys, Thomas A. Lograsso, Nicholas J. Jones, Deborah L. Schlagel, Gabriela Petculescu, Marilyn Wun-Fogle, James B. Restorff, Arthur E. Clark, Kristi B. Hathaway Jan 2015

Effects Of Zn Additions To Highly Magnetoelastic Fega Alloys, Thomas A. Lograsso, Nicholas J. Jones, Deborah L. Schlagel, Gabriela Petculescu, Marilyn Wun-Fogle, James B. Restorff, Arthur E. Clark, Kristi B. Hathaway

Ames Laboratory Publications

Fe1−xMx (M = Ga, Ge, Si, Al, Mo and x ∼ 0.18) alloys offer an extraordinary combination ofmagnetoelasticity and mechanical properties. They are rare-earth-free, can be processed using conventional deformation techniques, have high magnetic permeability, low hysteresis, and low magnetic saturation fields, making them attractive for device applications such as actuators and energy harvesters. Starting with Fe-Ga as a reference and using a rigid-band-filling argument, Zhang et al. predicted that lowering the Fermi level by reducing the total number of electrons could enhance magnetoelasticity. To provide a direct experimental validation for Zhang's hypothesis, elemental additions with lower-than-Ga valence are ...


Rhombohedral Magnetostriction In Dilute Iron (Co) Alloys, Nicholas J. Jones, Gabriela Petculescu, Marilyn Wun-Fogle, James B. Restorff, Arthur E. Clark, Kristi B. Hathaway, Deborah L. Schlagel, Thomas A. Lograsso Jan 2015

Rhombohedral Magnetostriction In Dilute Iron (Co) Alloys, Nicholas J. Jones, Gabriela Petculescu, Marilyn Wun-Fogle, James B. Restorff, Arthur E. Clark, Kristi B. Hathaway, Deborah L. Schlagel, Thomas A. Lograsso

Ames Laboratory Publications

Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, λ111 , is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t2g states unfilled, possibly favoring small internal ...


Influence Of Ga-Concentration On The Electrical And Magnetic Properties Of Magnetoelectric Cogaxfe2− Xo4/Batio3 Composite, Yan Ni, Zhen Zhang, Cajetan I. Nlebedim, David C. Jiles Jan 2015

Influence Of Ga-Concentration On The Electrical And Magnetic Properties Of Magnetoelectric Cogaxfe2− Xo4/Batio3 Composite, Yan Ni, Zhen Zhang, Cajetan I. Nlebedim, David C. Jiles

Electrical and Computer Engineering Publications

Multiferroic materials exhibit magnetoelectric (ME) coupling and promise new device applications including magnetic sensors, generators, and filters. An effective method for developing ME materials with enhanced ME effect is achieved by the coupling through the interfacial strain between piezoelectric and magnetostrictive materials. In this study, the electrical and magnetic properties of Ga doped magnetoelectric CoGaxFe2−xO4/BaTiO3composite are studied systematically. It is found that Ga doping improves the sensitivity of magnetoelastic response and stabilizes the magnetic phase of the composites. More importantly, Ga doping reduces the electrical conductivity of composite, as well as the dielectric loss. An enhancement of the ...


Influence Of Composition And Heat Treatment On Damping And Magnetostrictive Properties Of Fe–18%(Ga + Al) Alloys, I. S. Golovin, V. V. Palacheva, V. Yu. Zadorozhnyy, J. Zhu, H. Jiang, J. Cifre, Thomas A. Lograsso Oct 2014

Influence Of Composition And Heat Treatment On Damping And Magnetostrictive Properties Of Fe–18%(Ga + Al) Alloys, I. S. Golovin, V. V. Palacheva, V. Yu. Zadorozhnyy, J. Zhu, H. Jiang, J. Cifre, Thomas A. Lograsso

Ames Laboratory Publications

The structure, magnetostriction and damping properties of Fe82Ga(18−x)Alx (x = 0, 5, 8, 12) alloys were analyzed. The anelastic response of Fe–18(Ga + Al) alloys was studied as a function of temperature (from 0 to 600 °C), frequency (from 0.01 to 200 Hz) and amplitude (from 0.0004% to 0.2%) of forced vibrations. The origin of the relatively high damping capacity of Fe–Ga–Al alloy at room temperature was determined by applying a magnetic field and different heat treatment regimes. The substitution of Ga by Al in Fe–18% Ga alloys was found to ...


Texture And Grain Morphology Dependencies Of Saturation Magnetostriction In Rolled Polycrystalline Fe83ga17, R. A. Kellogg, A. B. Flatau, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso May 2013

Texture And Grain Morphology Dependencies Of Saturation Magnetostriction In Rolled Polycrystalline Fe83ga17, R. A. Kellogg, A. B. Flatau, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

Textured polycrystalline Fe-Ga alloys exhibit magnetostrictive strains of 100 ppm or greater and may function as a mechanically robust actuator/sensing material. Current efforts seek to combine the 300+ ppm magnetostrictive strain performance of [100] oriented single crystals with the mechanical properties of polycrystalline forms. One approach to combining these properties is to control the crystallographic texture through deformation processing such as rolling. To determine the relationship between saturation magnetostriction, degree of texturing, and grain morphology we compare the results of three-dimensional finite element simulations with the analytical solution for a random polycrystal and the experimental responses of rolled polycrystalline ...


Temperature Dependence Of Magnetoelastic Properties Of Fe100−Xsix (5 < X < 20), G. Petculescu, P. K. Lambert, A. E. Clark, K. B. Hathaway, Qingfeng Xing, Thomas A. Lograsso, J. B. Restorff, M. Wun-Fogle Feb 2012

Temperature Dependence Of Magnetoelastic Properties Of Fe100−Xsix (5 < X < 20), G. Petculescu, P. K. Lambert, A. E. Clark, K. B. Hathaway, Qingfeng Xing, Thomas A. Lograsso, J. B. Restorff, M. Wun-Fogle

Ames Laboratory Conference Papers, Posters, and Presentations

Tetragonal magnetostriction (λγ,2) and elastic constants (c′, c44, and c11) for Fe100−xSixwere measured as a function of temperature (T). Compositions corresponding to the disordered A2 (x = 5), ordered D03 (x = 19.8), and mixed (x = 11.6) phases, were investigated. The magnetoelastic coupling (−b1) was determined for 77 < T < 300 K and compared with those of Fe-Ga, Fe-Ge, and Fe-Al. Both λγ,2(T) and −b1(T) of Fe-Si behave similarly to those of Fe-Ge, while other notable differences exist between the measured properties of Fe-Si and those of the other three alloys. Due to the early establishment of short ...


Tetragonal Magnetostriction And Magnetoelastic Coupling In Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, And Fe-Ga-Ge Alloys, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, A. E. Clark, Thomas A. Lograsso, G. Petculescu Jan 2012

Tetragonal Magnetostriction And Magnetoelastic Coupling In Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, And Fe-Ga-Ge Alloys, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, A. E. Clark, Thomas A. Lograsso, G. Petculescu

Ames Laboratory Publications

This paper presents a comparative study on the tetragonal magnetostriction constant,λγ,2, [ = (3/2)λ100] and magnetoelastic coupling, b1, of binary Fe100-xZx (0 < x < 35, Z = Al, Ga, Ge, and Si) and ternary Fe-Ga-Al and Fe-Ga-Ge alloys. The quantities are corrected for magnetostrains due to sample geometry (the magnetostrictive form effect). Recently published elastic constant data along with magnetization measurements at both room temperature and 77 K make these corrections possible. The form effect correction lowers the magnetostriction by ∼10 ppm for high-modulus alloys and by as much as 30 ppm for low-modulus ...


Magnetostriction, Elasticity, And D03 Phase Stability In Fe–Ga And Fe–Ga–Ge Alloys, G. Petculescu, K. L. Ledet, Mianliang Huang, Thomas A. Lograsso, Y. N. Zhang, R. Q. Wu, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway Mar 2011

Magnetostriction, Elasticity, And D03 Phase Stability In Fe–Ga And Fe–Ga–Ge Alloys, G. Petculescu, K. L. Ledet, Mianliang Huang, Thomas A. Lograsso, Y. N. Zhang, R. Q. Wu, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway

Ames Laboratory Conference Papers, Posters, and Presentations

The contrast between the saturation tetragonal magnetostriction, λγ,2 = (3/2)λ100, of Fe1−xGax and Fe1−yGey, at compositions where both alloys exhibit D03 cubic symmetry (second peak region), was investigated. This region corresponds to x = 28 at. % Ga and y = 18 at. % Ge or, in terms of e/a = 2 x + 3 y + 1, to an e/a value of ∼1.55 for each of the alloys. Single crystal, slow-cooled, ternary Fe1−xy GaxGey alloys with e/a ∼1.55 and gradually increasing y ...


Experimental Exploration Of The Origin Of Magnetostriction In Single Crystalline Iron, Qingfeng Xing, Thomas A. Lograsso, M. P. Ruffoni, C. Azimonte, S. Pascarelli, D. J. Miller Aug 2010

Experimental Exploration Of The Origin Of Magnetostriction In Single Crystalline Iron, Qingfeng Xing, Thomas A. Lograsso, M. P. Ruffoni, C. Azimonte, S. Pascarelli, D. J. Miller

Ames Laboratory Publications

The magnetostrictive atomic strain in a pure Fe single crystal was measured by differential x-ray absorption spectroscopy. The obtained tetragonal magnetostriction constant, (3/2)λ100, was determined to be 45 ppm, consistent with the previously reported theoretical value calculated from a spin-orbit coupling theory. These results provide a foundation for understanding the origin of magnetostriction in pure Fe as well as Fe-based binary alloys.


The Effect Of Partial Substitution Of Ge For Ga On The Elastic And Magnetoelastic Properties Of Fe–Ga Alloys, G. Petculescu, A. O. Mandru, William M. Yuhasz, Thomas A. Lograsso, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway Apr 2010

The Effect Of Partial Substitution Of Ge For Ga On The Elastic And Magnetoelastic Properties Of Fe–Ga Alloys, G. Petculescu, A. O. Mandru, William M. Yuhasz, Thomas A. Lograsso, M. Wun-Fogle, J. B. Restorff, A. E. Clark, K. B. Hathaway

Ames Laboratory Conference Papers, Posters, and Presentations

Both components of the tetragonal magnetoelastic constant b1: the saturation magnetostriction, λγ,2 = (3/2)λ100, and the magnetic-field saturated shear elasticity, c′ = (c11c12)/2, were investigated over a wide temperature range for the magnetostrictiveFe1−xyGaxGey alloys, (x+y ≅ 0.125, 0.185, and 0.245; x/y ≅ 1 and 3). The magnetostriction was measured from 77 to 425 K using standard strain gage techniques. Both shear elastic constants (c′ and c44) were measured from 5 to 300 K using resonant ultrasound spectroscopy. Six alloy compositions were ...


Magnetostrictive And Elastic Properties Of Fe100−Xmox (2, Mianliang Huang, A. O. Mandru, G. Petculescu, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso Apr 2010

Magnetostrictive And Elastic Properties Of Fe100−Xmox (2, Mianliang Huang, A. O. Mandru, G. Petculescu, A. E. Clark, M. Wun-Fogle, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

In this paper we investigate the magnetostrictive [(3/2)λ100 and (3/2)λ111] and elastic (c′and c44) behavior of single crystalline alloys Fe100−xMox for 21 and −b2) are computed from the measurements. Similar to other Fe–X (X = Al, Ga, and Ge) alloys, the tetragonal magnetostriction (3/2)λ100 increases monotonically from ∼ 70×10−6 at ∼ 2.5 at. % Mo to a maximum of either ∼ 100×10−6 at ∼ 8 at. % Mo for the slow cooled crystals or ∼ 125×10−6 at ∼ 11 at. % Mo for quenched crystals. A ...


Magnetoelasticity Of Fe–Si Single Crystals, Qingfeng Xing, D. Wu, Thomas A. Lograsso Apr 2010

Magnetoelasticity Of Fe–Si Single Crystals, Qingfeng Xing, D. Wu, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

The tetragonal magnetostriction constant, (3/2)λ100, of Fe–Si single crystals was measured and was found to be structure dependent. Similar to that of Fe–Ge single crystals, (3/2)λ100 is positive in the single phase A2 regime, becomes negative in the single phase D03 regime, and changes from positive to negative between the two regimes. Short-range order in the A2 regime decreases the magnetostriction prior to the onset of long range order. In the single phase regions of both A2 and D03, thermal history does not show any obvious effect on the magnetostriction ...


Effect Of Carbon Addition On The Single Crystalline Magnetostriction Of Fe-X (X = Al And Ga) Alloys, Mianliang Huang, Yingzhou Du, Robert J. Mcqueeney, Thomas A. Lograsso Mar 2010

Effect Of Carbon Addition On The Single Crystalline Magnetostriction Of Fe-X (X = Al And Ga) Alloys, Mianliang Huang, Yingzhou Du, Robert J. Mcqueeney, Thomas A. Lograsso

Ames Laboratory Publications

The effect of carbon addition on the magnetostriction of Fe–Ga and Fe–Al alloys was investigated and is summarized in this study. It was found that the addition of carbon generally increased the magnetostriction over binary alloys of Fe–Ga and Fe–Al systems. The formation of carbide in the Fe–Ga–C alloys with a composition near D03 phase region decreased the magnetostriction drastically. Fe–Al–C and Fe–Ga–C alloys responded differently to thermal treatments; the magnetostriction in the quenched Fe–Al–C alloys is equal to or slightly lower than that of the slow ...


Magnetoelastic Coupling In Fe100−Xgex Single Crystals With 4, G. Petculescu, J. B. Leblanc, M. Wun-Fogle, J. B. Restorff, William M. Yuhasz, Thomas A. Lograsso, A. E. Clark Mar 2009

Magnetoelastic Coupling In Fe100−Xgex Single Crystals With 4, G. Petculescu, J. B. Leblanc, M. Wun-Fogle, J. B. Restorff, William M. Yuhasz, Thomas A. Lograsso, A. E. Clark

Ames Laboratory Conference Papers, Posters, and Presentations

In this paper we examine the elastic (c′ and c44) and magnetostrictive (λ100 and λ111) behaviors of Fe100−xGex for 4<x<18, quantities used further to find the fundamental magnetoelastic coupling constants b1 and b2 at room temperature. The x dependence ofb1 and b2 for Fe100−xGex is contrasted to those of Fe100−xGax and Fe100−xAlx. While the rhombohedral shear elastic constant c44 is almost insensitive to the type and amount of solute, the tetragonal shear constant c′ shows a pronounced and rapid softening with increasing x for ...


Magnetic Domains In Magnetostrictive Fe–Ga Alloys, Qingfeng Xing, Thomas A. Lograsso Nov 2008

Magnetic Domains In Magnetostrictive Fe–Ga Alloys, Qingfeng Xing, Thomas A. Lograsso

Ames Laboratory Publications

Lorentz microscopy was applied to the observation of magnetic domains in iron-gallium (Fe–Ga) alloys. Results did not show any link between the magnetic domains and the magnetostriction enhancement by Ga addition, but did reveal that the drastic decrease in magnetostriction for Fe–31.2 at. % Ga was due to the presence of large scale precipitates. Magnetic domain features did not change in the alloys of A2, D03, A2+D03,A2+B2+D03, and A2+fine scale precipitates. Large scale precipitates within the slow-cooled Fe–31.2 at. % Ga affected both the distribution and wall motion of ...


Effect Of Interstitial Additions On Magnetostriction In Fe–Ga Alloys, Mianliang Huang, Thomas A. Lograsso, A. E. Clark, J. B. Restorff, M. Wun-Fogle Jan 2008

Effect Of Interstitial Additions On Magnetostriction In Fe–Ga Alloys, Mianliang Huang, Thomas A. Lograsso, A. E. Clark, J. B. Restorff, M. Wun-Fogle

Ames Laboratory Conference Papers, Posters, and Presentations

The additions of trace amounts of small interstitial atoms (carbon, boron, and nitrogen) to Fe–Ga (Galfenol) alloys have a small but beneficial effect on the magnetostriction of Fe–Ga alloys especially at high Ga compositions. The saturated magnetostrictions [(3/2)λ100’s] of both slow cooled and quenched single crystal Fe–Ga–C alloys with Ga contents >18 at. % are about 10%–30% higher than those of the comparable binary Fe–Ga alloys. For boron and nitrogen additions, the magnetostrictions of slow cooled alloys with Ga content >18 at. % were approximately 20% higher than those of the binary ...


Temperature Dependence Of The Magnetostriction And Magnetoelastic Coupling In Fe100−Xalx (X = 14.1,16.6,21.5,26.3) And Fe50co50, A. E. Clark, J. B. Restorff, M. Wun-Fogle, D. Wu, Thomas A. Lograsso Jan 2008

Temperature Dependence Of The Magnetostriction And Magnetoelastic Coupling In Fe100−Xalx (X = 14.1,16.6,21.5,26.3) And Fe50co50, A. E. Clark, J. B. Restorff, M. Wun-Fogle, D. Wu, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

In this paper, we report magnetostriction measurements, (λ100) on Fe-rich Fe–Al alloys and Fe50Co50 as functions of temperature from 77 K to room temperature (RT). From these measurements and elastic constant (c′) measurements, the tetragonal magnetoelastic coupling constants (b1’s) were calculated. Significant differences were found between our RT measurements and earlier magnetostriction measurements for the higher Al concentration alloys (16.6%, 21.5%, 26.3% Al) and the Fe50Co50 alloy. Reminiscent of the temperature dependence of λ100 for pure Fe, magnetostriction changes with temperature are minimal for Fe–Al ...


Magnetostriction Of Iron-Germanium Single Crystals, D. Wu, Qingfeng Xing, R. William Mccallum, Thomas A. Lograsso Jan 2008

Magnetostriction Of Iron-Germanium Single Crystals, D. Wu, Qingfeng Xing, R. William Mccallum, Thomas A. Lograsso

Ames Laboratory Conference Papers, Posters, and Presentations

The addition of nonmagnetic Ga into body-centered cubic Fe enhances the magnetostriction constant λ100 over tenfold. Literature reports for substitution of Ge at low concentrations suggest that the addition of Ge also enhances the magnetostriction. In this work, the magnetostriction and microstructure of Fe–Ge were investigated to correlate magnetostriction with microstructure. The magnetostriction of Fe100−xGexsingle crystals with x between 0.05 and 0.18 varies with Ge concentration and correlates with phase changes. The value of (3/2)λ100 increases with Ge additions in the A2 single phase region (up to x ...


Irreversible Field Induced Magnetostriction At Temperatures Above And Below The Order-Disorder Transition In Single Crystal Tb5si2.2ge1.8, A. P. Ring, Thomas A. Lograsso, Deborah L. Schlagel, J. E. Snyder, David C. Jiles May 2007

Irreversible Field Induced Magnetostriction At Temperatures Above And Below The Order-Disorder Transition In Single Crystal Tb5si2.2ge1.8, A. P. Ring, Thomas A. Lograsso, Deborah L. Schlagel, J. E. Snyder, David C. Jiles

Ames Laboratory Conference Papers, Posters, and Presentations

This paper reports on the behavior of single crystal Tb5Si2.2Ge1.8 in the vicinity of its order-disorder and order-order phase transition from a higher temperature paramagnetic∕monoclinic state to a lower temperature ferromagnetic∕orthorhombic state. Measurements have been made of thermal and field induced changes in strain along the crystallographic a axis. The material exhibits large strains of up to 1500 ppm when a magnetic field is applied to it in its paramagnetic state but much smaller strains when a field is applied to it in its ferromagnetic state. These field induced strains are ...


Magnetostriction Of Ternary Fe–Ga–X (X = C,V,Cr,Mn,Co,Rh) Alloys, A. E. Clark, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, Thomas A. Lograsso, Mianliang Huang, E. Summers Apr 2007

Magnetostriction Of Ternary Fe–Ga–X (X = C,V,Cr,Mn,Co,Rh) Alloys, A. E. Clark, J. B. Restorff, M. Wun-Fogle, K. B. Hathaway, Thomas A. Lograsso, Mianliang Huang, E. Summers

Ames Laboratory Conference Papers, Posters, and Presentations

Binary iron-gallium (Galfenol) alloys have large magnetostrictions over a wide temperature range. Single crystal measurements show that additions of 2 at. % or greater of 3d and 4d transition elements with fewer (V, Cr, Mo, Mn) and more (Co, Ni, Rh) valence electrons than Fe, all reduce the saturation magnetostriction. Kawamiya and Adachi [J. Magn. Magn. Mater. 31–34, 145 (1983)] reported that the D03 structure is stabilized by 3dtransition elements with electron∕atom ratios both less than iron and greater than iron. IfD03 ordering decreases the magnetostriction, the maximum magnetostriction should ...


Variation Of Magnetostriction With Temperature In Tb5si2.2ge1.8 Single Crystal, A. P. Ring, H. L. Ziegler, Thomas A. Lograsso, Deborah L. Schlagel, J. E. Snyder, David C. Jiles Apr 2006

Variation Of Magnetostriction With Temperature In Tb5si2.2ge1.8 Single Crystal, A. P. Ring, H. L. Ziegler, Thomas A. Lograsso, Deborah L. Schlagel, J. E. Snyder, David C. Jiles

Ames Laboratory Conference Papers, Posters, and Presentations

The Tb5(SixGe4−x) alloy system is similar to the better known Gd5(SixGe4−x), except it has a more complex magnetic and structural phase diagram. Gd5(SixGe1−x)4 has received much attention recently due to its giant magnetocaloric effect, colossal magnetostriction and giant magnetoresistance in the vicinity of a first order combined magnetic-structural phase transition. The magnetostriction changes that accompany the phase transitions of single crystal Tb5(Si2.2Ge1.8) have been investigated at temperatures between 20 and150 K by measurements of ...


Lattice And Spin Dynamics In Bcc Fe, 10 At. % Be, P. Zhao, J. Cullen, M. Wuttig, H. J. Kang, J. W. Lynn, Thomas A. Lograsso, O. Moze Apr 2006

Lattice And Spin Dynamics In Bcc Fe, 10 At. % Be, P. Zhao, J. Cullen, M. Wuttig, H. J. Kang, J. W. Lynn, Thomas A. Lograsso, O. Moze

Ames Laboratory Conference Papers, Posters, and Presentations

Body centered cubic Fe1−xBex alloys are known to display an enhanced tetragonal magnetostriction compared to Fe. In order to characterize the enhanced magnetoelasticity observed in this alloy system, we present detailed inelastic neutron scattering measurements of the phonon dispersion relations of a single crystal of bcc Fe, 10 at. %Be along the high symmetry directions [100], [110], and [111] at room temperature. We observe in particular that the frequency of transverse phonons propagating along the [110] direction with a [10] polarization at the zone boundary is reduced by 10% with respect to bcc Fe (the corresponding ...


Large Magnetically Induced Strains In Ni50mn28.7ga21.3 Driven With Collinear Field And Stress, A. Malla, M. J. Dapino, Thomas A. Lograsso, Deborah L. Schlagel Mar 2006

Large Magnetically Induced Strains In Ni50mn28.7ga21.3 Driven With Collinear Field And Stress, A. Malla, M. J. Dapino, Thomas A. Lograsso, Deborah L. Schlagel

Ames Laboratory Publications

Despite the huge magnetic-field-induced strain (MFIS) of up to 9.5% exhibited by certain Ni–Mn–Ga alloys, their usefulness in applications is severely hindered by the electromagnet device needed for driving the alloys with a magnetic field and orthogonal loading stress. In this paper we present macroscopic measurements obtained from a single crystal of Ni50Mn28.7Ga21.3 which demonstrate a large reversible MFIS of −4100 ppm when the alloy is driven with quasistatic magnetic fields and fixed compressive stresses applied collinearly along the [001] axis. This collinear configuration marks a fundamental difference with prior ...


Versatile And Compact Capacitive Dilatometer, G. M. Schmiedeshoff, A. W. Lounsbury, D. J. Luna, S. J. Tracy, A. J. Schramm, S. W. Tozer, V. F. Correa, S. T. Hannahs, T. P. Murphy, E. C. Palm, A. H. Lacerda, Sergey L. Bud'ko, Paul C. Canfield, J. L. Smith, J. C. Lashley, J. C. Cooley Jan 2006

Versatile And Compact Capacitive Dilatometer, G. M. Schmiedeshoff, A. W. Lounsbury, D. J. Luna, S. J. Tracy, A. J. Schramm, S. W. Tozer, V. F. Correa, S. T. Hannahs, T. P. Murphy, E. C. Palm, A. H. Lacerda, Sergey L. Bud'ko, Paul C. Canfield, J. L. Smith, J. C. Lashley, J. C. Cooley

Ames Laboratory Publications

We describe the design, construction, calibration, and operation of a relatively simple differential capacitive dilatometer suitable for measurements of thermal expansion and magnetostriction from 300 to below 1K with a low-temperature resolution of about 0.05Å. The design is characterized by an open architecture permitting measurements on small samples with a variety of shapes. Dilatometers of this design have operated successfully with a commercial physical property measurement system, with several types of cryogenic refrigeration systems, in vacuum, in helium exchange gas, and while immersed in liquid helium(magnetostriction only) to temperatures of 30mK and in magnetic fields to 45T.


Fe–Ga/Pb(Mg1/3nb2/3)O3–Pbtio3 Magnetoelectric Laminate Composites, Shuxiang Dong, Junyi Zhai, Naigang Wang, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso Nov 2005

Fe–Ga/Pb(Mg1/3nb2/3)O3–Pbtio3 Magnetoelectric Laminate Composites, Shuxiang Dong, Junyi Zhai, Naigang Wang, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso

Ames Laboratory Publications

We have found large magnetoelectric (ME) effects in long-type laminate composites of Fe–20%Ga magnetostrictive alloys and piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals. At lower frequencies, the ME voltage coefficient of a laminate with longitudinally magnetized and longitudinally polarized (i.e., L-L mode) layers was 1.41 V/Oe (or1.01 V/cm Oe). Near the natural resonant frequency ( ∼ 91 kHz) of the laminate, the ME voltage coefficients were found to be dramatically increased to 50.7 V/Oe (36.2 V/cm Oe)for the L-L mode. In ...


Magnetic Force Microscopy Investigation Of Domain Structures In Fe–X At. % Ga Single Crystals (12, Feiming Bai, Jiefang Li, D. Viehland, D. Wu, Thomas A. Lograsso Jul 2005

Magnetic Force Microscopy Investigation Of Domain Structures In Fe–X At. % Ga Single Crystals (12, Feiming Bai, Jiefang Li, D. Viehland, D. Wu, Thomas A. Lograsso

Ames Laboratory Publications

The domain structure of furnace-cooled (FC) and post-annealed (PA) Fe–x at. % Ga (x = 12, 20, and 25) crystals has been investigated by magnetic force microscopy. For both FC and PA Fe–12 at. % Ga, the domains were found to be well-aligned and oriented along the [100] direction. For Fe–20 at. % Ga, although a preferred [100] orientation remained, a difference in morphology was found between FC and PA conditions—in the PA condition, clear dendritic domains were observed. For both FC and PA Fe–25 at. % Ga, a much reduced [100] preferred domain orientation was found, the domain size ...


Magnetic Field Dependence Of Galfenol Elastic Properties, G. Petculescu, K. B. Hathaway, Thomas A. Lograsso, M. Wun-Fogle, A. E. Clark May 2005

Magnetic Field Dependence Of Galfenol Elastic Properties, G. Petculescu, K. B. Hathaway, Thomas A. Lograsso, M. Wun-Fogle, A. E. Clark

Ames Laboratory Conference Papers, Posters, and Presentations

Elastic shear moduli measurements on Fe100−xGax (x = 12–33) single crystals (via resonant ultrasound spectroscopy) with and without a magnetic field and within 4–300 K are reported. The pronounced softening of the tetragonal shear modulus c′ is concluded to be, based on magnetoelastic coupling, the cause of the second peak in the tetragonal magnetostriction constant λ100 near x = 28. Exceedingly high ΔE effects ( ∼ 25%), combined with the extreme softness in c′ (c′<10 GPa), suggest structural changes take place, yet, gradual in nature, as the moduli show a smooth dependence on Ga concentration, temperature, and magnetic field. Shear anisotropy (c44/c′) as high as 14.7 was observed for Fe71.2Ga28.8.


Temperature Dependence Of The Magnetic Anisotropy And Magnetostriction Of Fe100−Xgax (X = 8.6, 16.6, 28.5), A. E. Clark, M. Wun-Fogle, J. B. Restorff, Kevin W. Dennis, Thomas A. Lograsso, R. William Mccallum May 2005

Temperature Dependence Of The Magnetic Anisotropy And Magnetostriction Of Fe100−Xgax (X = 8.6, 16.6, 28.5), A. E. Clark, M. Wun-Fogle, J. B. Restorff, Kevin W. Dennis, Thomas A. Lograsso, R. William Mccallum

Ames Laboratory Conference Papers, Posters, and Presentations

The temperature dependence of the lowest order magnetic anisotropy constant K1 and the lowest order saturation magnetostriction constant, (3/2)λ100, were measured from 4 K to 300 K for Fe91.4Ga8.6,Fe83.4Ga16.6, and Fe71.5Ga28.5 and were compared to the normalized magnetization power law, ml(l+1)/2. Fe91.4Ga8.6 maintains the magnetostriction anomaly of Fe (dλ100/dT>0) and K1 is a reasonable fit to the ml(l+1)/2power law with ...


Magnetostrictive And Magnetoelectric Behavior Of Fe–20 At. % Ga/Pb(Zr,Ti)O3 Laminates, Shuxiang Dong, Junyi Zhai, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso Apr 2005

Magnetostrictive And Magnetoelectric Behavior Of Fe–20 At. % Ga/Pb(Zr,Ti)O3 Laminates, Shuxiang Dong, Junyi Zhai, Feiming Bai, Jiefang Li, D. Viehland, Thomas A. Lograsso

Ames Laboratory Publications

The magnetostrictive and magnetoelectric (ME) properties of laminate composites of Fe–20 at. % Ga and Pb(Zr,Ti)O3 (PZT) have been studied for laminates of different geometries. The results show that (i) a long-type magnetostrictive Fe–20 at. % Ga crystal plate oriented along 〈001〉c and magnetized in its longitudinal (or length) direction has higher magnetostriction than a disk-type one; and consequently (ii) a long-type Fe–20 at. % Ga/PZT laminate has a giant ME effect, and is sensitive to low-level magnetic fields.


Magnetostriction And Elasticity Of Body Centered Cubic Fe100−Xbex Alloys, A. E. Clark, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, G. Petculescu Jun 2004

Magnetostriction And Elasticity Of Body Centered Cubic Fe100−Xbex Alloys, A. E. Clark, M. Wun-Fogle, J. B. Restorff, Thomas A. Lograsso, G. Petculescu

Ames Laboratory Conference Papers, Posters, and Presentations

Magnetostriction measurements from 77 K to room temperature on oriented (100) and (110) disk samples of Fe93.9Be6.1 and Fe88.7Be11.3 reveal substantial increases in λ100compared to iron. For the 11.3% alloy, λ100=110 ppm, a sixfold increase above that of α-Fe. For the 6.1% alloy, λ100=81 ppm, ∼40% and ∼170% greater than λ100 of comparable Fe–Ga and Fe–Al alloys, respectively, for H=15 kOe. Large differences exist between the values of λ100 and λ111 (λ100>0, λ111 ...