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Gadolinium is paramagnetic at room temperature, with a ferromagnetic Curie point of 20 °C (68 °F). [12] Paramagnetic ions, such as gadolinium, increase nuclear spin relaxation rates, making gadolinium useful as a contrast agent for magnetic resonance imaging (MRI).
The World Health Organization issued a restriction on use of several gadolinium contrast agents in November 2009 stating that "High-risk gadolinium-containing contrast agents (Optimark, Omniscan, Magnevist, Magnegita, and Gado-MRT ratiopharm) are contraindicated in patients with severe kidney problems, in patients who are scheduled for or have ...
The gadolinium ion, Gd 3+, has the f 7 electronic configuration, with all spins parallel. Compounds of the Gd 3+ ion are the most suitable for use as a contrast agent for MRI scans . [ 30 ] The magnetic moments of gadolinium compounds are larger than those of any transition metal ion.
Gadolinium has a spontaneous magnetization just below room temperature (293 K) and is sometimes counted as the fourth ferromagnetic element. There has been some suggestion that Gadolinium has helimagnetic ordering, [5] but others defend the longstanding view that Gadolinium is a conventional ferromagnet. [6]
Ferromagnetic, paramagnetic, ferrimagnetic, and antiferromagnetic materials have different intrinsic magnetic moment structures. At a material's specific Curie temperature (T C), these properties change. The transition from antiferromagnetic to paramagnetic (or vice versa) occurs at the Néel temperature (T N), which is analogous to Curie ...
Ferrofluids are a good example, but the phenomenon can also occur inside solids, e.g., when dilute paramagnetic centers are introduced in a strong itinerant medium of ferromagnetic coupling such as when Fe is substituted in TlCu 2 Se 2 or the alloy AuFe. Such systems contain ferromagnetically coupled clusters that freeze out at lower temperatures.
Spectral lines of gadolinium: Other properties; Natural occurrence: primordial: ... ferromagnetic–paramagnetic transition at 293.4 K : Molar magnetic susceptibility
Most contrast agents are either paramagnetic (e.g.: gadolinium, manganese, europium), and are used to shorten T1 in the tissue they accumulate in, or super-paramagnetic (SPIONs), and are used to shorten T2 and T2* in healthy tissue reducing its signal intensity (negative contrast agents).