  The symmetron field has an environment (density) dependent behavior which is
a common feature of the models with the screening mechanism and results in a
rich phenomenology. This model can produce domain walls between regions with
different densities. We consider this aspect and study the physics of domain
walls in between (underdensity) voids and (overdensity) halo structures. The
(spherical) domain walls exert a repulsive force on a test mass outside of the
wall while a test mass inside of the wall sees no force. This makes the
structures outside the voids go further to a larger radius. Effectively, this
means the voids are becoming larger in this scenario in comparison to the
standard model of cosmology. Interestingly, this makes voids emptier which may
shed light on Peebles' void phenomenon.
