Structure-Property Correlations in Sb, Ge, and Ga Doped AlFe2B2 for Magnetocaloric Applications
Abstract
This study investigates the effects of Sb, Ge, and Ga doping in AlFe2B2 on magnetic and magneto-caloric properties. Samples of AlFe2B2 and AlFe1.9M0.1B2 (M= Ge, Ga and Sb) with 20\% excess Al were synthesized by arc melting, and the powder processed were investigated for their phase constituents, microstructure, magnetic and magneto-caloric effect. The parent compounds prepared showed the AlFe2B2 phase with a FeB secondary phase. However, in Sb and Ga-doped samples, an additional impurity phase, Al13Fe4, was observed apart from FeB, while in Ge-doped, only the AlB2 impurity phase was present. The Curie temperature of AlFe2B2 is 277 K, increasing with Sb, Ge, and Ga doping to 287\,K, 297\,K, and 296\,K, respectively. The magnetization (M) is also higher with Ge and Ga addition in the 100-300\,K range; however, with Sb doping, the M decreases significantly compared to parent AlFe2B2. The magnetic entropy change under 2\,T reached 2.93 JKg-1K-1 near 274\,K in AlFe2B2, which decreases to 2.53 JKg-1K-1 and 1.92 JKg-1K-1 with Ge and Ga, respectively. With Sb doping, the MC change was affected dramatically to 0.32 JKg-1K-1. However, the relative cooling power of Ge doped is the same as that of parent AlFe2B2. This research advances the understanding of the relationship between doping elements and magnetic properties in AlFe2B2 and opens pathways for designing magneto-caloric materials with tailored magnetic characteristics.
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