Entropy changes due to the first-order phase transition in the Gd5SixGe4−x system

Liu, G. J.; Sun, J. R.; Lin, Jixiang; Xie, Yigao; Zhao, Tongyun; Zhang, H. W.; Shen, Baogen

doi:10.1063/1.2201879

Cited by 58 publications

(35 citation statements)

References 22 publications

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“…Secondly, the entropy contribution from latent heat is approximately 50% of the total entropy change, which is comparable to the contribution estimated from the structural component of 40-60%. 4,6 Lastly, as the temperature is increased (and the critical field, H c increases) there is only a small change in ΔS LH , i.e. the field and temperature accessible here does not significantly broaden the transition (or decouple the magnetic and structural components).…”

Section: Resultsmentioning

confidence: 99%

“…3 Studies suggest that the structural contribution to entropy change, ΔS str , is of the order of 40-60% of the total entropy change, ΔS Total . 4,5,6 We use here the separation of the latent heat and the heat capacity terms to probe the first order characteristics of the field driven phase transition in single crystal Gd 5 Si 2 Ge 2 with the field applied along the b-axis.…”

Section: Introductionmentioning

confidence: 99%

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Asymmetry of the latent heat signature in b-axis oriented single crystal Gd₅Si₂Ge₂

Morrison¹,

Pecharsky

Gschneidner

et al. 2011

MRS Proc.

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A 100 micron fragment of a b-axis oriented single crystal Gd5Si2Ge2 has been studied using microcalorimetry, enabling the separate measurement of the heat capacity and the latent heat. The sample was taken from the same crystal previously studied with Hall probe imaging, which showed that the phase transition is seeded by a second phase of Gd5Si1.5Ge1.5 nanoplatelets on the increasing field sweep direction only. The multiple transition features observed in the latent heat signature suggests a nucleation size of approximately 20 μm, consistent with the lengthscale suggested by Hall imaging. The difference in nucleation and growth process with field sweep direction is clearly identified in the latent heat. We show that the latent heat contribution to the entropy change is of the order of 50% of the total entropy change and unlike other systems studied, the transition does not broaden (and the latent heat contribution does not diminish significantly) as magnetic field and temperature are increased within the parameter range explored in these experiments.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd₅Si₂Ge₂

Morrison¹,

Pecharsky

Gschneidner

et al. 2011

MRS Proc.

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“…12 For Gd 4 Si x Ge 4−x , this contribution is found to be lower, varying from 20% to 40%. 17 In Mn 1−x Cr x CoGe, the amount of orth. phase below T c is strongly reduced with increasing the Cr content ͑see Table I͒.…”

mentioning

confidence: 99%

From single- to double-first-order magnetic phase transition in magnetocaloric Mn1−xCrxCoGe compounds

Trung

Biharie

Zhang

et al. 2010

Applied Physics Letters

217

110

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Substitution of some Cr for Mn atoms in MnCoGe was employed to control the magnetic and structural transitions in this alloy to coincide, leading to a single first-order magnetostructural transition from the ferromagnetic to the paramagnetic state with a giant magnetocaloric effect observed near room temperature. Further increase in the Cr content in the Mn1−xCrxCoGe alloys can induce another first-order magnetoelastic transition from the antiferromagnetic to the ferromagnetic state occurring at lower temperature. The giant magnetocaloric effect as well as the simultaneous tunability of the two magnetic transitions make these materials promising for future cooling applications.

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“…(1) Electromotor; (2) active system; (3) weight; (4) friction moment sensor; (5) data acquisition system; (6) computer; (7) principal axis; (8) special jig; (9) ball sample; (10) disc sample; (11) support of disc sample; (12) locating pin. sample (10), which is fixed by another jig (11). A locating pin (12), of size of   2 mm × 3 mm, is used to keep the disc sample (10) and the jig (11) coaxial.…”

Section: Methodsmentioning

confidence: 99%

“…As a result of the long-range ordered superlattice structures of intermetallic compounds, their metallic bonds are strong. FF eutectic alloys therefore have some special physical, chemical, and mechanical properties, such as high hardness and melting points, low thermal expansion coefficients, and excellent thermal conductivity [10][11][12]. New materials with these features can be used in the transport, chemicals, machinery, and many other industries.…”

mentioning

confidence: 99%

Electromagnetic modification of faceted-faceted Ni31Si12-Ni2Si eutectic alloy

et al. 2012

Chin. Sci. Bull.

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In an electromagnetic field, the morphology of a binary faceted-faceted (FF) Ni 31 Si 12 -Ni 2 Si eutectic microstructure and the alloy's mechanical properties were investigated. Hardness experiments demonstrated that the solidified ingots were significantly strengthened, and the hardness was improved to 63.1 and 786.6 on the Rockwell hardness C and Vickers hardness scales, respectively. Tests of friction and wear in stirred FF eutectic alloys showed excellent anti-fatigue and anti-adhesion wear performance. Alloy changed from an anomalous microstructure to a refined quasi-regular structure, and there was an increase in the lamellar microstructure fraction. The formation process of the refined quasi-regular microstructure and the resulting mechanical properties were investigated. Eutectic alloys of types (1) and (2) are widely used in various industrial fields. Theoretical research on the solidification mechanisms of such alloys shows that most NN and FN eutectic alloys can obtain regular lamellar or rod-like eutectic structures when they solidify under near-equilibrium condition [5][6][7]. However, the third type of binary eutectic alloy, i.e. FF eutectic alloys, has rarely been investigated. These alloys generally consist of two intermetallic compounds [8,9]. As a result of the long-range ordered superlattice structures of intermetallic compounds, their metallic bonds are strong. FF eutectic alloys therefore have some special physical, chemical, and mechanical properties, such as high hardness and melting points, low thermal expansion coefficients, and excellent thermal conductivity [10][11][12]. New materials with these features can be used in the transport, chemicals, machinery, and many other industries. For instance, the binary FF Si-TaSi 2 eutectic alloy is used in field-emission materials [13]. The hardness and strengths of some other binary FF eutectic alloys remain unchanged with increasing temperature. The Mo 5 Si 3 -MoSi 2 alloy is a case in point. At temperatures near 1400°C, the strength, thermal conductivity, electrical conductivity, and high-temperature oxidation resistance remain excellent, although these properties fail in other common alloys; this makes it extremely competitive among new high-temperature coating materials [14,15].For high solution entropies, anisotropic growth of the eutectic phase is strong in the solidification process and the solidified structure is extremely complex. It is very difficult for such eutectic alloys to achieve a regular structure under

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Entropy changes due to the first-order phase transition in the Gd5SixGe4−x system

Cited by 58 publications

References 22 publications

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd₅Si₂Ge₂

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd₅Si₂Ge₂

From single- to double-first-order magnetic phase transition in magnetocaloric Mn1−xCrxCoGe compounds

Electromagnetic modification of faceted-faceted Ni31Si12-Ni2Si eutectic alloy

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Entropy changes due to the first-order phase transition in the Gd5SixGe4−x system

Cited by 58 publications

References 22 publications

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd5Si2Ge2

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd5Si2Ge2

From single- to double-first-order magnetic phase transition in magnetocaloric Mn1−xCrxCoGe compounds

Electromagnetic modification of faceted-faceted Ni31Si12-Ni2Si eutectic alloy

Contact Info

Product

Resources

About

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd₅Si₂Ge₂

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd₅Si₂Ge₂