Stability and Magnetocaloric Properties of Sintered La(Fe, Mn, Si)$_{13}$H$_{z}$ Alloys

Barcza, Alexander; Katter, M.; Zellmann, V; Russek, Steven L.; Jacobs, S. D.; Zimm, C. B.

doi:10.1109/tmag.2011.2147774

Cited by 139 publications

(85 citation statements)

References 5 publications

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“…The transition temperature T C0 of the sample in the recombined state is around 296 K on heating, where T C is defined as the peak maximum of the temperature derivative. As in previous measurements of this material, [16][17][18] the single sharp transition decomposes on splitting into two separate transitions with two distinctive T C s which corresponds to a splitting of the peak in the derivative of the magnetization. While in previous reports the "peak taken in a magnetic field of 100 Oe on heating.…”

Section: Methodssupporting

confidence: 67%

“…However, it has recently been discovered that the single, sharp magnetic phase transition of partially hydrogenated LaFe 13−x Si x H y (y < 1.75) is unstable. [16][17][18] The transition has been seen to split into two separate transitions with distinctive T C s when the material is kept close to its unsplit phase transition temperature, T C0 . Such a split of T C implies that a diffusion of hydrogen atoms has taken place within the material, leading to hydrogen segregation and hence an inhomogeneous distribution of T C s.…”

Section: Introductionmentioning

confidence: 99%

“…In the simplest model, diffusion of the hydrogen atoms would take place from the lower volume PM phase to the higher volume FM phase 16,17 since the ferromagnetic unit cell volume is about 1 to 2% larger while the symmetry of the cubic crystal structure is preserved. 5,19,20 As a result, the T C of the PM regions T C1 decreases while the T C of the FM regions T C2 increases, stabilizing the resulting states and eventually leading to the appearance of two distinctive magnetic phase transitions.…”

Section: Introductionmentioning

confidence: 99%

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The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy

Baumfeld

Gercsi

Krautz

et al. 2014

Journal of Applied Physics

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By means of time-and temperature-dependent magnetization measurements, we demonstrate that the timescale of hydrogen diffusion in partially-hydrogenated LaFe 13−x Si x H y is of the order of hours, when the material is held at temperatures close to its as-prepared Curie temperature, T C0 . The diffusion constant is estimated to be D ≈ 10 −15 -10 −16 m 2 s −1 at room temperature. We examine the evolution of a magnetically phase-separated state upon annealing for 3 days at a range of temperatures around T C0 , and show that the thermodynamic driving force behind hydrogen diffusion and phase segregation may be attributed to the lower free energy of hydrogen interstitials in the ferromagnetic state relative to the paramagnetic state.

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Section: Methodssupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy

Baumfeld

Gercsi

Krautz

et al. 2014

Journal of Applied Physics

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“…[1][2][3] Magnetic marterials showing large low-field magnetocaloric effect have been attracting increasing attention over the past few decades due to their potential applications for magnetic refrigeration. During the past decades, a large MCE in the roomtemperature range has been observed in several classes of materials including Gd 5 (Si,Ge) 4 ; 4 MnAs and Mn(As,Sb); 5,6 (Mn,Fe) 2 (P,X) with X = As, Ge, Si; [7][8][9] (Mn,Fe) 2 (P,Si,B); 10 MnCoGeB x ; 11 MnCoGe 1Àx Ga x ; 12 MnCo 1Àx Fe x Si; 13 La(Fe,Si) 13 and their hydrides; 14,15 La(Mn,Fe,Si) 13 H z ; 16 Fe 49 Rh 51 17 and…”

Section: Introductionmentioning

confidence: 99%

Effect of Carbon Doping on the Structure and Magnetic Phase Transition in (Mn,Fe2(P,Si))

Thắng

Yibole

Miao

et al. 2017

JOM

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Given the potential applications of (Mn,Fe 2 (P,Si))-based materials for roomtemperature magnetic refrigeration, several research groups have carried out fundamental studies aimed at understanding the role of the magneto-elastic coupling in the first-order magnetic transition and further optimizing this system. Inspired by the beneficial effect of the addition of boron on the magnetocaloric effect of (Mn,Fe 2 (P,Si))-based materials, we have investigated the effect of carbon (C) addition on the structural properties and the magnetic phase transition of Mn 1:25 Fe 0:70 P 0:50 Si 0:50 C z and Mn 1:25 Fe 0:70 P 0:55 Si 0:45 C z compounds by x-ray diffraction, neutron diffraction and magnetic measurements in order to find an additional control parameter to further optimize the performance of these materials. All samples crystallize in the hexagonal Fe 2 Ptype structure (space group P-62m), suggesting that C doping does not affect the phase formation. It is found that the Curie temperature increases, while the thermal hysteresis and the isothermal magnetic entropy change decrease by adding carbon. Room-temperature neutron diffraction experiments on Mn 1:25 Fe 0:70 P 0:55 Si 0:45 C z compounds reveal that the added C substitutes P/Si on the 2c site and/or occupies the 6k interstitial site of the hexagonal Fe 2 Ptype structure.

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“…Currently, several types of magnetocaloric materials (MCM) are intensively developed and frequently used in prototype magnetic refrigerators. Among these materials are compounds of GdGe-Si [1], MnFe(P,Si) [2], MnFe(P,As) [3], La-Fe-Si [4], La(Fe,Si)H [5,6], La(Fe,Co)Si [7][8][9] and La(Fe,Mn)Si-H [10]. The newly emerging solutions use La-Fe-Sior Mn-Fe-P compounds due to their entropy changes |∆S M AX | = (10÷25) J kg −1 K −1 and the adiabatic temperature changes ∆T AD = (5 ÷ 7) K in a magnetic field µ 0 H less than 2 T [11].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties and Flux Distribution in the LaFeCoSi/FeCoV Hybrid Structure

2017

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The study contains a description of magnetic properties of LaFeCoSi/FeCoV structure. The hybrid structure contains magnetocaloric LaFeCoSi core with high-induction ferromagnetic laminations. The magnetic field inside the magnetic structure is gained by the fringe field from FeCoV laminations. Results of modelling and experimental investigations of modified magnetic properties of LaFeCoSi/FeCoV structure were presented and discussed in the paper.

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Stability and Magnetocaloric Properties of Sintered La(Fe, Mn, Si)$_{13}$H$_{z}$ Alloys

Cited by 139 publications

References 5 publications

The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy

The dynamics of spontaneous hydrogen segregation in LaFe13−xSixHy

Effect of Carbon Doping on the Structure and Magnetic Phase Transition in (Mn,Fe2(P,Si))

Magnetic Properties and Flux Distribution in the LaFeCoSi/FeCoV Hybrid Structure

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