Synthesis, Structure, and Magnetic Properties of Cyanurates RE 5 (C 3 N 3 O 3 )(OH) 12 ( RE = Gd-Lu): Cryogenic Magnetocaloric Candidate Gd 5 (C 3 N 3 O 3 )(OH) 12 .

Rare-earth ( RE )-based frustrated magnets are fertile playgrounds for discovering exotic quantum phenomena and exploring adiabatic demagnetization refrigeration applications. Here, we report the synthesis, structure, and magnetic properties of a family of rare-earth cyanurates RE 5 (C 3 N 3 O 3 )(OH) 12 ( RE = Gd-Lu) with an acentric space group P 6̅2 m . Magnetic susceptibility χ( T ) and isothermal magnetization M ( H ) measurements manifest that RE 5 (C 3 N 3 O 3 )(OH) 12 ( RE = Gd, Dy-Yb) compounds exhibit no magnetic ordering down to 2 K, while Tb 5 (C 3 N 3 O 3 )(OH) 12 shows long-range magnetic ordering around 3.6 K. Among them, magnetically frustrated spin- 7 / 2 Gd 5 (C 3 N 3 O 3 )(OH) 12 shows long-range magnetic ordering around 1.25 K and a large magnetocaloric effect with a maximum magnetic entropy change Δ S m of up to 58.1 J kg -1 K -1 at Δ H = 7 T at liquid-helium temperature regimes.