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Abstract Martensitic transformation (MT), magnetic properties, and magnetocaloric effect (MCE) in Heusler-type Ni 47 Mn 40 Sn 13− x Cd x ( x = 0, 0.75, 1, 1.25 at. %) metamagnetic shape memory alloys (MetaMSMAs) are investigated, both experimentally and theoretically, as a function of doping with Cd. Ab-initio computations reveal that the ferromagnetic (FM) configuration is energetically more favorable in the cubic phase than the antiferromagnetic (AFM) state in undoped and doped alloys as well. Moreover, it is revealed that the alloys in the ground state exhibit a tetragonal structure confirming the existence of MT, in agreement with the experiments. It was indicated, both in theory and practice, that a reduction of the unit cell volume and an increase of the MT temperature as a function of the Cd doping. Indirect estimations of MCE in the vicinity of MT were carried out by using thermomagnetization curves measured under different magnetic fields up to 5 T. The results demonstrated that the doped alloys exhibit enhanced values of the inverse MCE comparable with those of Ni-Mn-based MetaMSMAs. Maximum magnetic entropy change in a field change of 2 T increases from 3.0 J .k g − 1 K − 1 for the undoped alloy to 3.4 and 5.0 J .k g − 1 K − 1 for the alloys doped with 0.75 and 1 at.% of Cd, respectively. The inverse and conventional MCE were explored by direct measurements of the adiabatic temperature change under the magnetic field change of 1.96 T. The Cd doping increased the maximum of inverse MCE by nearly 78% from 0.9 K to 1.6 K for the undoped and doped alloys, respectively. The results depicted that Cd doping can effectively tailor the structural, magnetic, and MCE properties of the Ni–Mn–Sn MetaMSMAs.
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Synthesis, crystal and electronic structure of BaLixCd13–x (x ≈ 2)
A new ternary phase has been synthesized and structurally characterized. BaLi x Cd 13– x ( x ≈ 2) adopts the cubic NaZn 13 structure type (space group Fm 3 ¯ c , Pearson symbol cF 112) with unit cell parameter a = 13.5548 (10) Å. Structure refinements from single-crystal X-ray diffraction data demonstrate that the Li atoms are exclusively found at the centers of the Cd 12 -icosahedra. Since a cubic BaCd 13 phase does not exist, and the tetragonal BaCd 11 is the most Cd-rich phase in the Ba–Cd system, BaLi x Cd 13– x ( x ≈ 2) has to be considered as a true ternary compound. As opposed to the typical electron count of ca. 27 e -per formula unit for many known compounds with the NaZn 13 structure type, BaLi x Cd 13– x ( x ≈ 2) only has ca. 26 e -, suggesting that both electronic and geometric factors are at play. Finally, the bonding characteristics of the cubic BaLi x Cd 13– x ( x ≈ 2) and tetragonal BaCd 11 are investigated using the TB-LMTO-ASA method, showing metallic-like behavior.
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- Award ID(s):
- 2004579
- PAR ID:
- 10411120
- Date Published:
- Journal Name:
- Frontiers in Chemistry
- Volume:
- 10
- ISSN:
- 2296-2646
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.3389/fchem.2022.991625
