Mechanochemical synthesis of erbium borohydride: Polymorphism, thermal decomposition and hydrogen storage

[摘要] A new erbium borohydride Er(BH4)(3) was synthesized from 3LiBH(4) and ErCl3 through mechanochemical processing. This rare-earth metal borohydride presents a primitive cubic structure with a = 10.74(1) angstrom, which is isostructural with the one previously reported for R(BH4)(3) (R = Y, Dy and Gd). During heating Er(BH4)(3) exhibits a reversible structural transformation at about 220 degrees C, analogous to that observed for Y(BH4)(3). Combination of thermal hydrogen desorption, DSC, XRPD and FTIR measurements allows to determine that thermal decomposition of Er(BH4)(3) starts at 230 degrees C and leads to 3.2 wt% of hydrogen release obtaining ErH2, an unknown intermediate compound and ErB4. It was observed that Er(BH4)(3) is partially reversible under 6.0 MPa of H-2 at 400 degrees C and absorbs about 20% of the total hydrogen capacity obtained experimentally. (C) 2013 Elsevier B. V. All rights reserved.

[发布日期] 2013-12-25

[关键词] Rare-earth metal;Borohydrides;Mechanical milling;Phase transition;Hydrogen storage