  Compressed hydrogen-rich compounds have received extensive attention as
appealing contenders for superconductors, and further challenges are
maintaining the stability and superconductivity of hydrides at lower pressures.
In this work, we found several novel hydrides YZrH6, YZrH8 and YZrH12 with
excellent superconductivity in the Y-Zr-H ternary system. Interestingly, YZrH6
with an A15-type structure can maintain dynamic stability down to 0.01 GPa and
still with a critical temperature (Tc) of 16 K. YZrH8 and YZrH12 have high Tc
of 70 K and 183 K at 200 GPa and 160 GPa, respectively. The phonon modes
associated with H atoms contribute significantly to the electron-phonon
coupling, and the H-driven electronic density of states play an important role
in superconductivity. These findings highlight relationship between the
H-driven electronic density of states, electron-phonon coupling and the
superconductivity in a distinct class of hydrides, opening new avenues for
designing and optimizing new hydrogen-rich high temperature superconductors.
