Switching of the Magnetocaloric Effect of Mn^II Glycolate by Water Molecules

Abstract

The transformation of Mn(II) glycolates (glc) between the three-dimensional coordination polymer [Mn(glc)2]n (1) and discrete mononuclear phase [Mn(glc)2 (H2O)2] (2) can be reversibly switched by water molecules, which dramatically change the magnetocaloric effect (MCE) of Mn(II) glycolates from the maximum of 6.9 J kg(-1) K(-1) in 1 to 60.3 J kg(-1) K(-1) in 2. This case example reveals that the effect of magnetic coupling on MCE plays a dominant role over that of other factors such as magnetic density for 3d-type magnetic refrigerants.

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

“…Future study on the cryogenic MCE shall turn the focus onto the other parameters such as ∆T ad , cooling power and even production cost, where the Mn-based materials become strong competitors. 11 Although we have to admit that the coordination complexes with organic ligands can never be so comparative with inorganic complexes in such sense, it should not be forgotten that the ambitions of molecular materials have never been just about the value. We have witnessed how the numerous complexes seems useless can be rationally modified into good candidates for magnetic coolants, and we have been continuously learning about the magneto-structural correlations during the design and synthesis of these complexes.…”

“…2-3 At an early stage, the cryogenic magnetic coolants are mainly the inorganic paramagnetic salts and oxides, such as Gd 2 (SO 4 ) 3 ·8H 2 O and Gd 3 Ga 5 O 12 (GGG). 4 In recent years, molecular materials suddenly emerged in this field as an unprecedented classification, and a lot of highly competitive molecular magnetic coolants of 3d, [5][6][7][8][9][10][11] 3d-4f 12-21 and 4f-types [22][23][24][25][26][27][28][29] have been synthesized and characterized. Their distinct advantages, such as stoichiometric composition, monodispersity and modifiability, have provided the researchers a perfect platform to realize the design strategies towards cryogenic magnetic coolants.…”

Magnetocaloric effect and thermal conductivity of Gd(OH)3 and Gd2O(OH)4(H2O)2

“…The magnetization of 1 and 2 increases steadily with the applied field and reaches 6.99 Nm B for 1 and 13.65 Nm B for 2 at 2 K and 7 T, in agreement with the calculated value of 7 Nm B for 1 and 14 Nm B for 2 respectively. 10 It was mentioned that the gravimetric entropy change larger than 50 J kg À1 K À1 at 2 K and DH = 7 T has only been observed in four compounds (Table 1), 4,5,17,18 while the volumetric entropy change larger than 210 mJ cm À3 K À1 has only observed in three compounds so far (including in the commercial magnetic refrigerant GGG 19 ), despite the great many efforts made. 11 As shown in Fig.…”

Ab initio structure determination of [Eu5(C2H4O2)6(CH3CO2)3] n by X-ray powder diffraction

“…They are mostly prepared and investigated as solid intermediates in the preparation of chemically, structurally and microstructurally controlled oxide particles (Takase et al, 2017;Das et al, 2009;Ksapabutr et al, 2004;Pan et al, 2015;Day et al, 1996;Ng et al, 2008;Yu et al, 2007Baklanova et al, 2014 or metal (Chakroune et al, 2005;Abdallah et al, 2015;Takahashi et al, 2016;Anžlovar et al, 2008), but they are also studied as intrinsic functional materials, taking advantage of the versatility of their crystalline structure, their lightness and, of course, the variety of their own physico-chemical properties. Typically, some of them, owing to the magnetic properties of their constitutive metal cations, exhibit interesting magnetocaloric properties at low temperature making them valuable for cryogenic magneto-refrigeration applications (Abdallah et al, 2019;Chen et al, 2014). Others, owing to the chelating properties of their organic component, namely glycolate ligands, allow a better reactivity in certain catalytic reactions, such as those involved in the polycondensation of ethylene glycol with bis-(hydroxyethyl)terephthalate for the production of poly(ethylene terephthalate) (PET) -an important thermoplastic material (Biros et al, 2002).…”