Pressure and Temperature Influence on the Desorption Pathway of the LiBH₄−MgH₂ Composite System

The decomposition pathway in LiBH 4 −MgH 2 reactive hydride composites was investigated systematically as a function of pressure and temperature. Individual decomposition of MgH 2 and LiBH 4 is observed at higher temperatures and low pressures ( T ≥ 450 °C and p (H 2 ) ≤ 3 bar), whereas simultaneous desorption of H 2 from LiBH 4 and formation of MgB 2 was observed at 400 °C and a hydrogen backpressure of p (H 2 ) = 5 bar. The simultaneous desorption of H 2 from LiBH 4 and MgH 2 without intermediate formation of metallic Mg could not be observed. In situ X-ray diffraction (XRD) and infrared (IR) spectroscopy reveal the present crystalline and amorphous phases.