Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-14T23:56:22.727Z Has data issue: false hasContentIssue false
  • English
  • Français

The Effect of Fe Substitutions on the Microstructure of Gd5Si2Ge2

Published online by Cambridge University Press:  26 February 2011

Benjamin Podmiljsak ,
Paul McGuiness ,
Spomenka Kobe  and
Irena Skulj
Benjamin Podmiljsak
Affiliation:
beno.podmiljsak@ijs.si, Josef Stefan Institute, Department for nanostructured materials, Jamova cesta 39, Ljubljana, 1000, Slovenia
Paul McGuiness
Affiliation:
paul.mcguiness@ijs.si, Josef Stefan Institute, Ljubljana, 1000, Slovenia
Spomenka Kobe
Affiliation:
spomenka.kobe@ijs.si, Josef Stefan Institute, Ljubljana, 1000, Slovenia
Irena Skulj
Affiliation:
irena.skulj@imt.si, Institute of metals and technology, Ljubljana, 1000, Slovenia
Get access

Abstract

Gd5Si2Ge2 exhibits the so-called giant magnetocaloric effect, making it a potential material for next-generation near-room-temperature permanent-magnet-based refrigeration devices. In the as-cast form this material is relatively complicated in terms of its structure and its metallurgy.

Recent reports have suggested that small additions of iron can substantially improve the problems associated with hysteresis losses, so enhancing the material's potential for real-world applications. We have looked at iron substitutions in the range X=0 to X=1 for Gd5Si2-XGe2 to investigate the macrostructures and microstructures of cast and homogenized materials, with particular emphasis on the amount of iron substituting for silicon in the Gd5(SiGe)4 phase and the effect of the substituting iron on the Ge/Si ratio. The larger iron substitutions were found to eliminate the unusual macrostructures, and conventional ingots with smooth surfaces were the result. The iron was also found to dissolve at levels of 1-3% in the Gd5(SiGe)4 phase and encourage the formation of the Gd5(SiGe)3 phase at the expense of the magnetocaloric Gd5(SiGe)4 phase. A substitution of X=1 was found to be sufficient to produce as-cast microstructures consisting almost entirely of the Gd5(SiGe)3 phase.

With a scanning electron microscope (Jeol 840A) and an analytical transmission electron microscope (Jeol 2010 F with a field-emission gun) and an EDXS system from Oxford Instruments (Link Isis 300) we performed a detailed microstructural investigation of the processed materials. Special emphasis was placed on the intergrain regions and an assessment of the amount of Fe substituting in the main magnetocaloric phase.

Keywords

magnetic propertiesmicrostructureFe
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1032: Symposium I – Nanoscale Magnetic Materials and Applications , 2007 , 1032-I11-09
Copyright
Copyright © Materials Research Society 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1 Pecharsky, VK, Gschneidner, KA Jr, Phys. Rev. Letts. 78(23) (1997) 4494 10.1103/PhysRevLett.78.4494Google Scholar
2 Morellon, L, Algarabel P, A, Ibarra M, R, Blasco, J, Garcia-Lannda, B, Arnold, Z, Albertini, F, Phys. Rev. B 58 (1998) R14721 Google Scholar
3 Choe, W, Pecharsky, Vk, Pecharsky, AO, Gschneidner, KA Jr, Young, VG, Miller, GJ., Phys. Rev. Letts. 84(20) (2000) 4617 10.1103/PhysRevLett.84.4617Google Scholar
4 Pecharsky, VK, Gschneidner, KA Jr, Appl. Phys. Letts. 70 (1997) 3299 10.1063/1.119206Google Scholar
5 Levin, E. M., Pecharsky, V. K. & Gschneidner, K. A. Jr, Phys. Rev. B 62, R14625–R14628 (2000).Google Scholar
6 Giguere, A. et al. Phys. Rev. Lett. 83, 2262–2265 (1999).10.1103/PhysRevLett.83.2262Google Scholar
7 Provenzano, V, Shapiro, A J, Shull, R D, Nature 429, 853–857 (24 June 2004)10.1038/nature02657Google Scholar