T-P phase diagram of the Mn-H system at pressures to 4.4 GPa and temperature to 1000 deg 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 alpha and beta allotropic modifications containing only a few atomic percent of hydrogen, a hydride on the basis of the gamma (fcc) modification and a hydride with an hcp( epsilon ) metal lattice. The phase diagram is characterized by two triple points, ( alpha + epsilon + gamma ) at approx0.7 GPa and 350 deg C and ( alpha + beta gamma ) at approx0.7 GPa and 700 deg C. The temperature of the epsilon - > gamma transition increases linearly with pressure and reaches approx850 deg C at 4.4 GPa.