Interstitial Effects on the Magnetic Phase Transition and Magnetocaloric Effects in (Hf, Ta)Fe 2 Kagome Phase
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ORIGINAL PAPER
Interstitial Effects on the Magnetic Phase Transition and Magnetocaloric Effects in (Hf, Ta)Fe2 Kagome Phase Shuai Li 1,2 & Haofa Wu 1,2 & Ni Zhao 1,2 & Jiamin Chen 3 & Yongjian Zhang 4 & Weibin Cui 1,2 Received: 15 April 2020 / Accepted: 16 June 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The effects of Ta substitution on the first-order phase transition have been firstly studied in Hf1-xTaxFe2 (x = 0.15, 0.165, 0.18) alloys with kagome-type lattice. Higher Ta substitution leads to the reduced metamagnetic transition temperature (Tt) from lowtemperature ferromagnetism to high-temperature antiferromagnetism and paramagnetism. By doping C atoms, the Tt is gradually reduced and thermal hysteresis becomes widened in the alloys with higher Ta substitution. The critical field which triggers the metamagnetic phase transition is not substantially affected by interstitial C atoms. With increased Ta substitution, for the field change of 7 T, the maximum of magnetic entropy change (ΔSmax) of 3.7 J kg−1 K−1 is obtained at x = 0.15 and enhanced to 4 J kg−1 K−1 at x = 0.165 but reduced to ~ 3.21 J kg−1 K−1 in Hf0.82Ta0.18Fe2 alloy. By C addition, both Tt and the temperature where ΔS is maximized are shifted to a lower temperature, especially in the higher Ta-contained alloys. Keywords (Hf, Ta)Fe2 phase . Metamagnetic phase transition . Magnetocaloric effect
1 Introduction AFe2 Laves compounds, where A can be early transition elements and rare-earth elements, have been intensively experimental and theoretical investigated. The interesting relationship between the magnetism and the crystal structure has been found. The magnetic ordering is sensitively dependent on the elements at the A site. In MgZn2-type hexagonal structure, ScFe2 and HfFe2 phases exhibit ferromagnetism [1, 2]. TiFe2 [3] and TaFe2 [4] show the antiferromagnetism. But, the NbFe2 phase displays the ground state of
* Jiamin Chen [email protected] * Weibin Cui [email protected] 1
Key Laboratory of Electromagnetic Processing of Materials, Department of Physics and Chemistry of Materials, Northeastern University, Shenyang 110819, China
2
State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China
3
State Key Laboratory of Transducer Technology (North base), The Aerospace Information Research Institute, CAS, Beijing 100190, China
4
Fujian Changting Golden Dragon Rare-Earth Co., Ltd, Longyan City 366309, Fujian, China
the spin-density wave [5, 6]. As a comparison, when rare-earth elements occupy A site, the cubic structure (C15) is formed with interesting magnetism. Particularly, RFe2 (R=Tb, Dy) phase is well known as the magnetostrictive material. Among them, the HfFe2 system has received lots of attention in the past decades. Its Curie temperature (Tc) is as high as 600 K [2, 7]. Its ferromagnetic ground state can be tuned by partially substituting Hf by Ta. When the Ta substitution amount, x in Hf1-xTaxFe2 alloy, is lower than 0.1, the FM ground state is still
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