2025-08-27 東京理科大学,科学技術振興機構
図2 準結晶と近似結晶
＜関連情報＞
- https://www.tus.ac.jp/today/archive/20250827_1138.html
- https://pubs.acs.org/doi/10.1021/jacs.5c05947
化学量論的2/1準結晶近似体からの非化学量論的1/1準結晶近似体の導出と磁気熱効果の最大化 Derivation of a Nonstoichiometric 1/1 Quasicrystal Approximant from a Stoichiometric 2/1 Quasicrystal Approximant and Maximization of the Magnetocaloric Effect
Farid Labib,Hiroyuki Takakura,Asuka Ishikawa,Takenori Fujii,and Ryuji Tamura
Journal of the American Chemical Society Published: August 27, 2025
DOI:https://doi.org/10.1021/jacs.5c05947
Abstract
The present research introduces a novel strategy for tuning magnetic properties by overcoming the compositional limitation of stoichiometric intermetallic compounds via extension of their compositional domain into the valence electron-per-atom (e/a) parameter space. Focusing on approximant crystals (ACs), a “double heterovalent elemental substitution” is employed in a stoichiometric Ga–Pt–Gd 2/1 AC whereby e/a is lowered from approximately 1.98 to 1.60. Through this approach, a new family of Ga-based Tsai-type 1/1 ACs with an exceptionally wide compositional domain within e/a space is derived. Remarkably, the magnetic ground state is altered from initially spin-glass to ferromagnetic (FM) with second-order phase transition and mean-field-like critical behavior. More importantly, through this strategy, the isothermal magnetic entropy change (ΔSM) enhanced significantly and reached a maximum value of −8.7 J/K mol-Gd under a 5 T magnetic field change, even comparable to leading rare-earth magnetocaloric materials including RCo2 phases. These findings demonstrate the high potential of a double heterovalent elemental substitution for tailoring magnetic properties and magnetocaloric response in stoichiometric compounds, offering a new pathway for designing high-performance magnetic refrigeration materials even beyond the quasicrystals and ACs.
