Phase control studies in Gd5Si2Ge2 giant magnetocaloric compound

• Type: Article in International Scientific Journal
• Date: 2012

Authors

belo, j. h. (Author) Other; pereira, a. m. (Author) FCUP; ventura, j. (Author) FCUP; oliveira, g. n. p. (Author) Other; araujo, j. p. (Author) FCUP; tavares, p. b. (Author) Other; fernandes, l. (Author) Other; algarabel, p. a. (Author) Other; magen, c. (Author) Other; morellon, l. (Author) Other; ibarra, m. r. (Author) Other

Journal

Title: Journal of Alloys and Compounds

Vol. 529

Pages: 89-95

ISSN: 0925-8388

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 24 Citations

Scopus - 24 Citations

Other information

Authenticus ID: P-002-7ZX

DOI: 10.1016/j.jallcom.2012.02.164

Abstract (EN): A systematic set of annealings on arc-melted synthesized Gd5Si2Ge2 sample was performed. Through powder X-ray diffraction (XRD) and magnetometry measurements we monitored the effect of varying the annealing time with constant temperature (T = 1473 K) on the formation of the monoclinic (M) crystallographic phase fraction, which is the one responsible for the giant magnetocaloric effect (GMCE) in this compound. The conversion of the orthorhombic O(I) crystallographic phase into M was achieved, resulting in a significant increase of the M mass fraction. Such conversion led to a change in the magnetic transition nature, evolving from a second to a first order transition for the as-cast and annealed samples, respectively. An optimal annealing time range for the M phase conversion was identified to be within 80-120 min at T = 1473 K followed by a rapid quenching to liquid N-2. Furthermore, an increase up to similar to 50% of the magnetocaloric effect was obtained for the sample annealed during 120 min.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7