  Due to the simple layered structure, isostructural FeSe and FeSe0.5Te0.5 are
clue compounds for understanding the principal mechanisms of superconductivity
in the family of Fe-based superconductors. High-pressure magnetic, structural
and M\"ossbauer studies have been performed on single-crystalline samples of
superconducting FeSe0.5Te0.5 with Tc = 13.5 K. Susceptibility data have
revealed a strong increase of Tc up to 19.5 K for pressures up to 1.3 GPa,
followed by a plateau in the Tc(p) dependence up to 5.0 GPa. Further pressure
increase leads to a disappearance of the superconducting state around 7.0 GPa.
X-ray diffraction and M\"ossbauer studies explain this fact by a
tetragonal-to-hexagonal structural phase transition. M\"ossbauer parameters of
the non-superconducting high-pressure phase indicate less covalency of Fe-Se
bonds. Based on structural and susceptibility data we conclude about a common
character of Tc(p) diagrams for both FeSe and FeSe0.5Te0.5 superconductors.
