A brilliant cryogenic magnetic coolant: magnetic and magnetocaloric study of ferromagnetically coupled GdF₃

Abstract

The use of paramagnetic molecules as cryogenic coolants usually requires relatively large fields to obtain a practical cooling effect. Thus, research for magnetic molecular materials with larger MCEs in fields of ≤ 2 T is the central science. In this work, the crystal structure, magnetic susceptibility and isothermal magnetization for inorganic framework material GdF 3 were measured, and the isothermal entropy change was evaluated up to 9 T. Thanks to combination of the large isotropic spin of Gd 3+ , the dense structure and the weak ferromagnetic interaction, an extremely large -∆S m for GdF 3 was observed up to 528 mJ cm -3 K -1 for ∆µ 0 H = 9 T, proving itself to be an exceptional cryogenic magnetic coolant.The magnetocaloric effect of a inorganic framework material with repeating unit of GdF 3 has been experimentally studied using isothermal magnetization and heat capacity measurements. The maximum entropy change -∆S max reaches 74.8 J kg -1 K -1 or 528 mJ cm -3 K -1 for ∆H = 9 T and T = 1.8 K.

High-performance low-temperature magnetic refrigerants made of gadolinium-hydroxy-chloride

“…The SEM analyses show that both of them have rod-like morphologies (Fig. 14 The content ratios of Gd : Cl derived from the XPS analysis are close to 3 : 1 and 1 : 1, which correspond to the formulae of [Gd 3 (OH) 8 Cl] n and [Gd(OH) 2 Cl] n for 1 and 2, respectively. Fig.…”

“…Herein, we provide a new family of dense inorganic magnetic refrigerants, [Gd 3 (OH) 8 Cl] n (1) and [Gd(OH) 2 Cl] n (2), based on gadolinium-hydroxy-chloride (GHC) compositions. Interestingly, the structures of both compounds feature triangular Gd 3 (m 3 -OH) units which extend in disparate ways.…”

Enhanced Magnetocaloric Effect from Cr Substitution in Ising Lanthanide Gallium Garnets Ln3CrGa4O12 (Ln = Tb, Dy, Ho)

“…[13] Of these, gadolinium gallium garnet (GGG), which shows no long-range ordering down to 25 mK, has been established as a MCM for magnetic refrigeration in the liquid helium temperature regime. The absence of long-range ordering, high density of magnetic ions, chemical stability, and lack of single ion anisotropy (L = 0 for Gd 3+ ) allowing for the full magnetic entropy (Rln[2J + 1] = 17.29 J K −1 mol Gd −1 ) to be extracted in high magnetic fields makes it an ideal MCM for T < 20 K. [14][15][16] In recent years, a number of Gd containing MCMs with better performance at 2 K have been reported [17][18][19][20] but GGG continues to be used and serves as the benchmark for MCMs in this temperature regime. However, for all the Gd-based magnetocalorics, the change in magnetic entropy is maximized in fields of 5 T or higher.…”

“…) to be extracted in high magnetic fields makes it an ideal MCM for T < 20 K. [14][15][16] In recent years, a number of Gd containing MCMs with better performance at 2 K have been reported [17][18][19][20] but GGG continues to be used and serves as the benchmark for MCMs in this temperature regime. However, for all the Gd-based magnetocalorics, the change in magnetic entropy is maximized in fields of 5 T or higher.…”

Gaudefroyite: a mineral with excellent magnetocaloric effect suitable for liquefying hydrogen

“…gadolinium gallium garnet (GGG), GdPO 4 ) or the more recently proposed molecular magnets. 9,10 The metallic ferromagnetic (FM) and the "giant" MC intermetallic materials 11,12 are also unsuitable because of long term degradation in contact with LH 2 .…”