Crystal structures and magnetocaloric properties of Li5ASrMB12O24(A = Mg, Zn; M = Cr, Ni)

Three new transition-metal-based borate crystals, Li 5 MgSrMB 12 O 24 (M ​= ​Cr, Ni) and Li 5 ZnSrNiB 12 O 24 , were obtained using the high temperature solution method. Their structures were determined by the single crystal X-ray diffraction, which crystallize in the trigonal R 3 ¯ space group. The [B 3 O 11 ] groups in the structures lead to the long distance between two nearest magnetic ions, which can reduce the interaction of adjacent magnetic centers. The magnetic properties and thermal stabilities of the title compounds were also investigated. The results indicated that Li 5 MgSrCrB 12 O 24 has stable chemical-physical properties and its maximum –ΔS m value of 14.33 ​J ​kg −1 ·K −1 at 2 ​K for Δμ 0 H  ​= ​9 ​T reaching 88.6% of the theoretical paramagnetic limit, suggesting its potential application on the magnetic refrigeration.