It is believed that the anionic electrons
localized in the crystallographic
subnanometer space (void, channel, and interlayer) can stabilize electrides
and affect their electronic and magnetic properties. However, the
influence of anionic electrons on the stability and properties of
electrides is not clear yet. In the present work, ab initio evolutionary
structure searches, combined with the first-principles calculations,
were employed to predict the stable structures of the Ba–P
system under external pressures of 0–20 GPa. Among these predicted
compounds, Ba5P3 and Ba8P5 were identified as 1D and 0D electrides, respectively. Our calculations
proved that anionic electrons dominate the magnetic and electronic
properties of Ba–P electrides. Moreover, it is revealed that
anionic electrons have two effects on the stability of electrides:
the stabilizing effect caused by the attraction of anionic electrons
and the surrounding cations in both 0D and 1D electrides and the destabilizing
effect caused by the repulsion between anionic electrons in 1D electrides.
Upon the applied external pressure, both effects can be weakened in
Ba5P3, while only the former effect was weakened
in Ba8P5. Therefore, the 1D electride Ba5P3 becomes thermodynamically stable over the 0D
electride Ba8P5 with increasing pressure, which
is opposite with the previous concept that the low-dimensional electrides
are usually more stable than the high-dimensional ones. The finding
of this study may shed light on the design and synthesis of new electrides
with different dimensions with the assistance of an external pressure.