The Production of Temperatures below One Degree Absolute by Adiabatic Demagnetization of Gadolinium Sulfate

Magnetocaloric effect in gadolinium-oxalate framework Gd2(C2O4)3(H2O)6⋅(0⋅6H2O)

“…1 Its use through the adiabatic demagnetization process has first focused on low temperatures. [2][3][4] Different kinds of materials have attracted interest for their MCE in low temperature region (2-4 K), including simple paramagnetic salts, 4,5 molecular nanomagnets, [6][7][8][9][10][11][12] extended porous networks, 13 garnets, 14 or intermetallic alloys. 15 For a more exhaustive insight, two recent review articles dealing with coordination compounds 16 or molecule-based 17 magnetic coolers can be consulted.…”

“…15 For a more exhaustive insight, two recent review articles dealing with coordination compounds 16 or molecule-based 17 magnetic coolers can be consulted. Nowadays magnetic cooling continues attracting attention for temperatures well below liquid He temperature because of the increasing cost and scarcity of 3 He, and in some cases as satellite applications, for its technological simplicity and independence from gravity.…”

“…Good candidates for low temperature applications are compounds in which Gd 3+ centers are sufficiently isolated from each other to retain a paramagnetic behavior down to about 2 K. Gadolinium sulfate hydrate constitutes an historical example. 2,3 For about 10 years, gadoliniumbased magnetic coolers have been sought in coordination compounds with light organic molecules as ligands with the aim of combining decoupled magnetic centers with large magnetic/nonmagnetic atoms mass ratios, which are essential characteristics for obtaining good magnetocaloric properties per units of volume. It has to be noticed that, although decoupled magnetic centers are good systems for cryogenic magnetic cooling, the existence of weak ferromagnetic interactions can be taken as an advantage.…”

“…5 Nevertheless, excellent performances in terms of MCE can also be found in compounds presenting weak a Author to whom correspondence should be addressed. antiferromagnetic interactions, such as the compact metal-organic framework (MOF) Gd(HCOO) 3 which takes advantage of formate, the lightest carboxylate. 18 Finally, we notice the advantages of certain magnetocaloric MOF materials in terms of robustness, which can be considered as an advantage in practical applications as we emphasized in the past with the study of Gd(HCOO)(C 8 H 4 O 4 ).…”

“…Gadolinium oxalate is described in two structural types: type 1, a high interstitial or "zeolitic water" content phase Gd 2 (C 2 O 4 ) 3 (H 2 O) 6 ·nH 2 O with n ∼2.5 (SG = P2 1 /a, a = 10.0549(4) Å, b = 9.6066(3) Å, c = 11.0306(6) Å, β = 114.097 (4) • , V = 972.63(7) Å 3 , and D x = 2.536 g/cm 3 ), 28 and type 2, free of "zeolitic water" content phase Gd 2 …”