Thermal analyses of the mixture of MgH2 and LiBH4 doped with TiCl3, and each element MgH2 or LiBH4 doped with TiCl3 were performed under an inert gas flow and 0.5 MPa H2-gas conditions. It was indicated that the hydrogen desorption reaction of MgH2 + 2LiBH4 to MgB2 + 2LiH + 4H2 phases proceeded at temperature above 400 °C under 0.5 MPa hydrogen, whereas, under an inert gas atmosphere, the reaction of the same mixture was transformed into Mg + 2B + 2LiH + 4H2 phases in a temperature range from 350 to 430 °C. Before these reactions, the dehydrogenation of MgH2 and the melting of LiBH4 took place under both hydrogen and the inert gas atmospheres with increasing temperature. In addition, the molten LiBH4 did not decompose into LiH, B and H2 below 450 °C under 1 MPa H2, while the LiBH4 decomposed even below 450 °C under an inert gas atmosphere. From these results, it is deduced that the reaction producing MgB2 is a solid-liquid reaction between solid Mg and liquid LiBH4 above 400 °C without decomposition of molten LiBH4 under a hydrogen atmosphere, while MgH2 dehydrogenate. A characteristic solid-liquid reaction is realized under a hydrogen atmosphere for proceeding of the MgB2 producing reaction in this system.
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