1 / 28

Advances in Magnetic Refrigerant Materials Research

This presentation, given by Lian Zhang at the WZI group meeting on May 28, 2003, explores the potential of magnetic refrigeration (MR) technologies. It discusses the fundamental principles of MR, highlighting its advantages over conventional gas expansion cooling, such as higher efficiency, reduced noise, and lower environmental impact. The search for effective magnetic refrigerant materials is reviewed, including Gd5(Si,Ge)4, Fe2Mn(Si,Ge), La(Fe,Si)13, and MnFe(P,As). The findings underscore the readiness of MR materials while identifying further opportunities for improvement and adaptation to engineering challenges.

yale
Télécharger la présentation

Advances in Magnetic Refrigerant Materials Research

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Search for magnetic refrigerant materials - Lian Zhang WZI group meeting May 28th 2003, UvA

  2. Outline • What & why is MR? • Search for candidate materials • Gd5(Si,Ge)4 • Fe2Mn(Si,Ge) • La(Fe,Si)13 • MnFe(P,As) • Conclusion

  3. Fleet FR de Boer, KHJ Buschow E Brück, A de Visser, J Klaasse, YK Huang O Tegus AL Wolf

  4. Why magnetic refrigeration? • Conventional gas expansion cooling • Ozone depletion • Global warming • Green MR • Higher efficiency • Less noisy • More compact • Low temperature capability

  5. Ericsson Q Q Magnetic Refrigeration • Magnetic-materials change in temperature if subjected to magnetic-field change Magnetocaloric effect B=0 Carnot S B0 T

  6. S Refrigerant capacity Table-like T S1 Sm S2 Tad T1 T2 Integration from isothermal magnetization curves Directly measure or compute from specific heat measurements

  7. Composite material B1 > B2 M S B T T1 T2 T3 T4 : : Tn TC Field-induced or not, behaves differently.

  8. Gd5(Si,Ge)4 Hysteresis M T Magnetostructural transition Misleading message

  9. O. Tegus Physica B 319 (2002) M. Nazih Solid State Comunications 126 (2003)

  10. Fe2Mn(Si1-xGex) • Fe3Si: • TC > 800 K • Fe2MnSi: • TC ~ 250 K • Cubic D03 • Heusler-type • Fe3Ge: • D019(HT) • L12(LT)

  11. D03  D019 L. Zhang J. Alloys Comp. 352 (2003)

  12. TC- Ge content Lattice change with Ge content

  13. L. Zhang Physica B 328 (2003)

  14. Disappointed!

  15. La(Fe,Si)13 • The highest 3d metal concentration (1:13) in RT intermetallic compounds • Failed to be a good permanent magnet • Cubic: weak anisotropy Palstra 1983

  16. Hypothetical LaFe13 structure: Space group = Fm-3c Unit cell = 8 f.u. = 112 atoms = 8 La + 8 FeI + 96 FeII FeI@8b FeII@96i Al, Si La @8a Moze 1999

  17. Modification • Substitution of Fe by other transition metals • Mn: failed to get single phase LaFe10.92Mn0.65Si1.43 • Co: LaFe10.92Co0.65Si1.43 has a 2nd transition at TC=265K • Doping with interstitial atoms • B: -Fe emerges in small amount of doping (B=0.2) • N: difficulty in diffusion makes sample inhomogeneous and broadens the transition enormously • C: saturated at C=0.5, while TC=250K

  18. Field step 0.005T Field step 0.1T Field step 0.02T Be cautious with the height of S peak when it is a 1st order field-induced transition.

  19. For the field-induced 1st order transition, the field-up S-T show point rotation symmetry with the field-down S-T curve.

  20. MnFe(P,As)

  21. s (B/f.u.) T(K) TN s 400 4 TN TC 3 300 AF AF TN 2 200 F AF 1 100 Orth Hex Tetr MnFeP MnFeAs Beckman-Lundgren, 1991

  22. O. Tegus Physica B 319 (2002)

  23. Virgin effect

  24. c b a c b a

  25. X=0.4 X=0.2

  26. X=0.4 X=0.2 X=0.2

  27. Conclusion • Materials for MR are ready • Much room for improvement • Behaviors vary: rich ingredients • Theories are called • Accommodate engineering challenges

More Related