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Microstructure and magnetocaloric effect in as‐quenched GdGeSi alloys with addition of Ni and Ce
Author(s) -
Hasiak Mariusz
Publication year - 2016
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201532812
Subject(s) - magnetic refrigeration , materials science , curie temperature , microstructure , alloy , thermomagnetic convection , atmospheric temperature range , analytical chemistry (journal) , magnetic field , crystallography , condensed matter physics , ferromagnetism , magnetization , metallurgy , thermodynamics , chemistry , physics , chromatography , quantum mechanics
Microstructure as well as AC and DC thermomagnetic properties were studied for the as‐quenched Gd 80 Ge 15 Si 5 , Gd 75 Ge 15 Si 5 Ni 5 and Gd 75 Ge 15 Si 5 Ce 5 (wt.%) alloys in a wide range of magnetic fields. The structural investigations performed by X‐ray diffractometry show the presence of Gd‐based phases in the investigated alloys. These results were also confirmed by structure investigations as temperature dependence of specific heat capacity. Besides the crystalline phases discovered in the samples the regions with different atom concentration were observed in Ni and Ce‐containing alloys. The Curie temperature for the Gd 80 Ge 15 Si 5 , Gd 75 Ge 15 Si 5 Ni 5 and Gd 75 Ge 15 Si 5 Ce 5 alloys is 272, 235, and 284 K, respectively. The magnetocaloric effect (MCE) calculated as magnetic entropy change (−Δ S M ) depends on magnetizing field and for the Gd 80 Ge 15 Si 5 and Gd 75 Ge 15 Si 5 Ni 5 alloys reaches almost the same maximum value of 12 J kg −1 K −1 . Ce‐containing sample shows about 2.4 times lower MCE than the master alloy. Magnetic entropy change (−Δ S M ) versus temperature for the Gd 80 Ge 15 Si 5 , Gd 75 Ge 15 Si 5 Ni 5 , and Gd 75 Ge 15 Si 5 Ce 5 alloys calculated for the maximum magnetizing field of 3 T.