T-P phase diagram of the Mn-H system at pressures to 4.4 GPa and temperatures to 1000 degrees C

The Mn-H phase diagram was constructed from the results of a room temperature X-ray study of powder samples exposed to molecular hydrogen at a given pressure and temperature. Within the studied T-P interval, manganese and hydrogen were shown to form four different phases: the primary solid solutions on the basis of the α and β allotropic modifications containing only a few atomic percent of hydrogen, a hydride on the basis of the γ (fcc) modification and a hydride with an hcp (ε) metal lattice. The phase diagram is characterized by two triple points, (α + ε + γ) at approximately 0.7 GPa and 350°C and (α + β+ γ) at approximately 0.7 GPa and 700°C. The temperature of the ε → γ transition increases linearly with pressure and reaches ≈ 850°C at 4.4 GPa.