Magnetic-entropy change in Mn/sub 1.1/Fe/sub 0.9/P/sub 1-x/Ge/sub x/ compounds

Dagula, W.; Tegus, O.; Fuquan, B.; Zhang, L.; Si, P.Z.; Zhang, M.; Zhang, W.S.; Brück, E.; Boer, F.R. de; Buschow, K.H.J.

doi:10.1109/tmag.2005.854774

Cited by 60 publications

(27 citation statements)

References 5 publications

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“…These changes and temperature dependencies are similar to those observed for the other compositions [7,10] of both the Mn 1.1 Fe 0.9 P 1-x Ge x and Mn 1.1 Fe 0.9 P 1-x As x compounds. [4] The Curie temperature, magnetic hysteresis width, and entropy changes reported [15] for Mn 1.1 Fe 0.9 P 0.8 Ge 0.2 are in reasonable agreement with the values given in Table 1.…”

Section: Magnetic Measurementssupporting

confidence: 86%

“…The series of MnFeP 1-x Ge x compounds, with x between 0.2 and 0.3 has been found [7] to be ferromagnetic with Curie temperatures increasing from 250 to 380 K and to have a magnetocaloric effect similar to that observed [4] in the MnFeP 1-x As x compounds.…”

Section: Introductionmentioning

confidence: 71%

“…Polycrystalline samples of the Mn 1.1 Fe 0.9 P 1-x Ge x compounds, with x = 0.16, 0.20, 0.22 and 0.26, were prepared as previously described [7]. The powder x-ray diffraction patterns were obtained with a Philips X'pert diffractometer equipped with Cu-K α radiation.…”

Section: Methodsmentioning

confidence: 99%

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A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn_1.1Fe_0.9P_1−xGe_xcompounds

Sougrati

Hermann

Grandjean

et al. 2008

J. Phys.: Condens. Matter

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The structural, magnetic and Mössbauer spectral properties of the magnetocaloric Mn 1.1 Fe 0.9 P 1-x Ge x compounds, with 0.19 < x < 0.26, have been measured between 4.2 and 295 K. The 295 K unit-cell volume increases from x = 0.19 to x = 0.22 and is substantially smaller in the ferromagnetic Mn 1.1 Fe 0.9 P 0.74 Ge 0.26 . The temperature dependence of the magnetization reveals ferromagnetic to paramagnetic transition with a Curie temperature between ca. 250 and 330 K and hysteresis width of 10 to 4 K, for 0.19 < x < 0.25. The composition Mn 1.1 Fe 0.9 P 0.78 Ge 0.22 shows the largest isothermal entropy change of ca. 10 J/(kgKT) at 290 K. The Mössbauer spectra have been analysed with a binomial distribution of hyperfine fields correlated with a change in isomer shift and quadrupole shift, a distribution that results from the distribution of phosphorus and germanium among the nearneighbours of the iron. The coexistence of paramagnetic and magnetically ordered phases in ranges of temperature of up to 50 K around the Curie temperature is observed in the Mössbauer spectra and is associated with the first-order character of the ferromagnetic to paramagnetic transition. The temperature dependence of the weighted average hyperfine field is well fit within the magnetostrictive model of Bean and Rodbell. Good fits of the Mössbauer spectra could only be achieved by introducing a difference between the isomer shifts in the paramagnetic and ferromagnetic phases, a difference that is related to the magnetostriction and electronic structure change.

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Section: Magnetic Measurementssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 71%

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A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn_1.1Fe_0.9P_1−xGe_xcompounds

Sougrati

Hermann

Grandjean

et al. 2008

J. Phys.: Condens. Matter

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“…However, this is still an extra step in the preparation process, and furthermore the alloy needs to be hydrogenated to raise the Curie temperature up to room temperature. For the FeMnPAs-base alloys, the Dutch scientists have been able to replace the As by doping with Si þ Ge without losing the good MCE properties (Dagula et al, 2005;Cam Thanh et al, 2006). However, since the alloy still contains P, special handling techniques in preparing these alloys are required because white P is a poison and every allotrope of this element has a high vapor pressure.…”

Section: Large Scale Production Of Giant Magnetocaloric Effect Materialsmentioning

confidence: 99%

Thirty years of near room temperature magnetic cooling: Where we are today and future prospects

Gschneidner

Pecharsky

2008

International Journal of Refrigeration

630

200

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SurveyTechnology History a b s t r a c tThe seminal study by Brown in 1976 showed that it was possible to use the magnetocaloric effect to produce a substantial cooling effect near room temperature. About 15 years later Green et al. built a device which actually cooled a load other than the magnetocaloric material itself and the heat exchange fluid. The major breakthrough, however, occurred in 1997 when the Ames Laboratory/Astronautics proof-of-principle refrigerator showed that magnetic refrigeration was competitive with conventional gas compression cooling.Since then, over 25 magnetic cooling units have been built and tested throughout the world. The current status of near room temperature magnetic cooling is reviewed, including a discussion of the major problems facing commercialization and potential solutions thereof. The future outlook for this revolutionary technology is discussed.

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“…12 Following this, Ó 2015 The Minerals, Metals & Materials Society many GMCE materials were discovered, most notably (values quoted for 0 to 2 T field change): La (Fe,Si) 13 and its hydrides (15 J kg À1 K À1 to 25 J kg À1 K À1 ; 4 K to 8 K), [17][18][19] (Mn,Fe) 2 (P,Si,Ge) compounds (12 J kg À1 K À1 to 25 J kg À1 K À1 ; 1.8 K), [20][21][22] and several Ni-Mn-based off-stoichiometric Heusler alloys (6 J kg À1 K À1 to 15 J kg À1 K À1 ; 2 K to 6 K). [23][24][25] In these classes of materials, the system transforms between two phases with different crystal structures and magnetizations, M. During the FOPT, the sudden structural change also creates an abrupt change in the system's entropy, DS, due to the latent heat of transformation, which contributes greatly to the GMCE.…”

Section: Introductionmentioning

confidence: 99%

A Preisach-Based Nonequilibrium Methodology for Simulating Performance of Hysteretic Magnetic Refrigeration Cycles

Brown

Bruno

Chen

et al. 2015

JOM

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In giant magnetocaloric effect (GMCE) materials a large entropy change couples to a magnetostructural first-order phase transition, potentially providing a basis for magnetic refrigeration cycles. However, hysteresis loss greatly reduces the availability of refrigeration work in such cycles. Here, we present a methodology combining a Preisach model for rate-independent hysteresis with a thermodynamic analysis of nonequilibrium phase transformations which, for GMCE materials exhibiting hysteresis, allows an evaluation of refrigeration work and efficiency terms for an arbitrary cycle. Using simplified but physically meaningful descriptors for the magnetic and thermal properties of a Ni 45 Co 5 Mn 36.6 In 13.4 at.% single-crystal alloy, we relate these work/efficiency terms to fundamental material properties, demonstrating the method's use as a materials design tool. Following a simple two-parameter model for the alloy's hysteresis properties, we compute and interpret the effect of each parameter on the cyclic refrigeration work and efficiency terms. We show that hysteresis loss is a critical concern in cycles based on GMCE systems, since the resultant lost work can reduce the refrigeration work to zero; however, we also find that the lost work may be mitigated by modifying other aspects of the transition, such as the width over which the one-way transformation occurs.

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Magnetic-entropy change in Mn/sub 1.1/Fe/sub 0.9/P/sub 1-x/Ge/sub x/ compounds

Cited by 60 publications

References 5 publications

A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn_1.1Fe_0.9P_1−xGe_xcompounds

A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn_1.1Fe_0.9P_1−xGe_xcompounds

Thirty years of near room temperature magnetic cooling: Where we are today and future prospects

A Preisach-Based Nonequilibrium Methodology for Simulating Performance of Hysteretic Magnetic Refrigeration Cycles

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Magnetic-entropy change in Mn/sub 1.1/Fe/sub 0.9/P/sub 1-x/Ge/sub x/ compounds

Cited by 60 publications

References 5 publications

A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn1.1Fe0.9P1−xGexcompounds

A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn1.1Fe0.9P1−xGexcompounds

Thirty years of near room temperature magnetic cooling: Where we are today and future prospects

A Preisach-Based Nonequilibrium Methodology for Simulating Performance of Hysteretic Magnetic Refrigeration Cycles

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Product

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A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn_1.1Fe_0.9P_1−xGe_xcompounds

A structural, magnetic and Mössbauer spectral study of the magnetocaloric Mn_1.1Fe_0.9P_1−xGe_xcompounds