  We find an order-disorder transition from crystals to disordered crystals for
static packings of frictionless spheres. While the geometric indicators are
mostly blind to the transition, disordered crystals already exhibit properties
apart from crystals. The transition approaches the close packing of hard
spheres, giving rise to the singularity of the close packing point. We evidence
that both the transition and properties of disordered crystals are jointly
determined by the structural orders and density. Near the transition, the
elastic moduli and coordination number of disordered crystals show particular
pressure dependence distinct from both crystals and jammed solids.
