Thermal properties of Y(BH_4)_3 synthesized via two different methods

摘要

Y(BH_4)_3 is one of the candidates for solid-state hydrogen storage, which contains 9.06 wt% of hydrogen. In this study, the thermal properties of Y(BH_4)_3 synthesized via two different methods are extensively examined. One method relies on the solid—solid metathesis reaction between LiBH_4 and YCl_3, and the other method is the gas—solid reaction between B_2H_6 and YH_3. The two samples are studied by differential scanning calorimetry, ther-mogravimetry, and X-ray diffraction. They exhibit distinctly different polymorphic phase transformation and melting. It turns out that the side product LiCl in the metathesis reaction, which has been regarded as being inert, shifts the melting point and promotes the formation of YB_4 during decomposition. Differential scanning calorimetry and in situ X-ray diffraction data indicate that the addition of LiBH_4 to Y(BH_4)_3 induces co-melting as is found in the cases of LiBH_4-Ca(BH_4)_2 or IiBH_4-Mg(BH_4)_2. Melt infiltration of Y(BH_4)_3 into mesoporous carbon cage confirms such melting behavior.