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Iowa State University

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Materials Science and Engineering

Germanium alloys

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Full-Text Articles in Physics

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 ...


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 ...


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 ...


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 ...


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 ...


Spontaneous Generation Of Voltage In Single-Crystal Gd5si2ge2 During Magnetostructural Phase Transformations, Min Zou, H. Tang, Deborah L. Schlagel, Thomas A. Lograsso, Karl A. Gschneidner Jr., Vitalij K. Pecharsky Apr 2006

Spontaneous Generation Of Voltage In Single-Crystal Gd5si2ge2 During Magnetostructural Phase Transformations, Min Zou, H. Tang, Deborah L. Schlagel, Thomas A. Lograsso, Karl A. Gschneidner Jr., Vitalij K. Pecharsky

Ames Laboratory Conference Papers, Posters, and Presentations

The spontaneous generation of voltage (SGV) in single-crystal and polycrystallineGd5Si2Ge2 during the coupled magnetostructural transformation has been examined. Our experiments show reversible, measurable, and repeatable SGV responses of the materials to the temperature and magnetic field. The parameters of the response and the magnitude of the signal are anisotropic and rate dependent. The magnitude of the SGV signal and the critical temperatures and critical magnetic fields at which the SGV occurs vary with the rate of temperature and magnetic-field changes.


Magnetic Anisotropy And Phase Transitions In Single-Crystal Tb5(Si2.2ge1.8), M. Han, J. E. Snyder, W. Tang, Thomas A. Lograsso, Deborah L. Schlagel, David C. Jiles May 2005

Magnetic Anisotropy And Phase Transitions In Single-Crystal Tb5(Si2.2ge1.8), M. Han, J. E. Snyder, W. Tang, Thomas A. Lograsso, Deborah L. Schlagel, David C. Jiles

Ames Laboratory Conference Papers, Posters, and Presentations

The Tb5(SixGe4−x) alloy system has many features in common with the Gd5(SixGe4−x)system although it has a more complex magnetic and structural phase diagram. This paper reports on the magnetic anisotropy and magnetic phase transition of single-crystalTb5(Si2.2Ge1.8) which has been investigated by the measurements of M-H and M-T along the a, b, and c axes. The variation of 1/χ vs T indicates that there is a transition from paramagnetic to ferromagnetic at Tc = 110 K. Below this ...


Dynamics Of The Magnetic Field-Induced First Order Magnetic-Structural Phase Transformation Of Gd5(Si0.5ge0.5)4, J. Leib, J. E. Snyder, Thomas A. Lograsso, Deborah L. Schlagel, David C. Jiles Jun 2004

Dynamics Of The Magnetic Field-Induced First Order Magnetic-Structural Phase Transformation Of Gd5(Si0.5ge0.5)4, J. Leib, J. E. Snyder, Thomas A. Lograsso, Deborah L. Schlagel, David C. Jiles

Ames Laboratory Conference Papers, Posters, and Presentations

The system Gd5(SixGe1−x)4 for 0.4⩽x⩽0.5 has been shown to have an unusual first order, coupled magnetic-structural phase transformation at the Curie temperature. Above the transformation temperature Tc, the material is paramagnetic with a monoclinic structure; below Tc, it is ferromagnetic with an orthorhombic structure. Another unusual feature of this phase transformation is that an applied magnetic field can increase Tc by 5 K per tesla. In this study, the magnetic-structural transformation in single crystalGd5Si2Ge2 was triggered by holding the sample at ...