AlFe2-xCoxB2(x = 0-0.30): TCTuning through Co Substitution for a Promising Magnetocaloric Material Realized by Spark Plasma Sintering.
AlFe2B2and AlFe2-xCoxB2(x = 0-0.30) were synthesized from the elements in three different ways. The samples were characterized by powder X-ray diffraction, Rietveld refinements, energy-dispersive X-ray spectroscopy, and magnetic measurements. Using Al flux the formation of AlFe2B2single crystals is preferred. Arc melting enables the substitution of ∼6% Co. This substitution of Fe by Co decreases the Curie temperature TCfrom 290 to 240 K. The highest Co substitution up to 15% is achieved by spark plasma sintering (SPS). TCis reduced to 205 K. In all cases an excess of Al is necessary to avoid the formation of ferromagnetic FeB. Al13Fe4-xCoxis the common byproduct. TCand the cobalt content are linearly correlated. The transition paramagnetic-ferromagnetic remains sharp for all examples. The magnetic entropy change of the Co-containing samples is comparable to AlFe2B2. SPS synthesis yields, in short reaction times, a homogeneous and dense material with small amounts of paramagnetic Al13Fe4-xCoxas an impurity, which can serve as sinter additive. These properties make AlFe2-xCoxB2a promising magnetocaloric material for applications between room temperature and 200 K.
Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität , Albertstraße 21, D-79104 Freiburg, Germany.
Sarah
S
Hirt
Department of Chemistry and Chemical Biology, McMaster University , Hamilton, Ontario L8S 4M1, Canada.
Fang
F
Yuan
Department of Chemistry and Chemical Biology, McMaster University , Hamilton, Ontario L8S 4M1, Canada.
Yurij
Y
Mozharivskyj
Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität , Albertstraße 21, D-79104 Freiburg, Germany.|Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität , Stefan-Meier-Straße 19, D-79104 Freiburg, Germany.
Harald
H
Hillebrecht