Structural and magnetocaloric properties of novel gadolinium borohydrides

Abstract

Novel Gd-based mixed-metal borohydrides A(n)Gd(BH4)(n+3) (A - K, Cs) are described in view of their magnetic cooling properties at cryogenic temperatures. The magnetic entropy changes correlate well with Gd3+ isolation and structural dimensionality in the discovered perovskite-type and other compounds. Crystal structures are resolved from Synchrotron X-ray Powder Diffraction and refined with solid state calculations. The isolated Gd-centres in five-fold coordination in K2Gd(BH4)(5), the first representative of a new structure type, lead to exceptionally high mass magnetic entropy change of 54.6 J kg(-1) K-1 at the maximum field change of 9 T. (C) 2016 Published by Elsevier B.V.