  As a new type of topological materials, ZrTe5 shows many exotic properties
under extreme conditions. Utilizing resistance and ac magnetic susceptibility
measurements under high pressure, while the resistance anomaly near 128 K is
completely suppressed at 6.2 GPa, a fully superconducting transition emerges
surprisingly. The superconducting transition temperature Tc increases with
applied pressure, and reaches a maximum of 4.0 K at 14.6 GPa, followed by a
slight drop but remaining almost constant value up to 68.5 GPa. At pressures
above 21.2 GPa, a second superconducting phase with the maximum Tc of about 6.0
K appears and coexists with the original one to the maximum pressure studied in
this work. In situ high-pressure synchrotron X-ray diffraction and Raman
spectroscopy combined with theoretical calculations indicate the observed
two-stage superconducting behavior is correlated to the structural phase
transition from ambient Cmcm phase to high-pressure C2/m phase around 6 GPa,
and to a mixture of two high-pressure phases of C2/m and P-1 above 20 GPa. The
combination of structure, transport measurement and theoretical calculations
enable a complete understanding of the emerging exotic properties in
three-dimensional topological materials happened under extreme environments.
