Synthesis of Mg 2 FeH 6 assisted by heat treatment of starting materials

Abstract Mg-based materials have become the cornerstone of hydrogen storage applications and have shown recently promises in thermal energy storage applications. However, synthesis of some materials including Mg 2 FeH 6 ternary hydride poses a number of challenges. In spite a variety of reports on various synthesis routes yielding Mg 2 FeH 6 , none of them produces a 100% pure Mg 2 FeH 6 . In this communication, we have attempted to synthesize Mg 2 FeH 6 by high energy reactive ball milling (HERBM) performed in hydrogen gas. Prior to the ball milling, the starting stoichiometric 2:1 mixture of the initial materials Mg+Fe was heat treated through a judicious temperature program. It was found that the yield of Mg 2 FeH 6 is related to the conditions of heat treatment, time and temperature, and the milling parameters such as ball to powder mass ratio (BPR) and rotation speed of the planetary mill. Moreover, it was found that the synthesis took place in less than 5 hours of milling with a maximum yield of Mg 2 FeH 6 of 84 wt%, which is a noticeable improvement as compared to the reference data.