  We report high $q$-resolution neutron scattering data on PMN-$x$PT single
crystals with $x=20%$ and 27%. No rhombohedral distortion occurs in the 20PT
sample for temperatures as low as 50 K. On the other hand, the 27PT sample
transforms into a rhombohedral phase below T$_C \sim 375$ K. Our data provide
conclusive evidence that a new phase with an average cubic lattice is present
in the bulk of this relaxor system at low PT concentration, in which the
ferroelectric polarization and lattice distortion are decoupled. The
rhombohedral distortion is limited to the outermost tens of microns of the
crystal.
