  We report measurements of the neutron diffuse scattering in a single crystal
of the relaxor ferroelectric material
95.5%Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$-4.5%PbTiO$_3$ (PZN-4.5%PT). Our results
suggest that the nanometer scale structure in this compound exhibits both
$<100>$ and $<110>$ polarizations, which contribute to different portions of
the total diffuse scattering intensity. These contributions can be
distinguished by the differing responses to an electric field applied along
[001]. While diffuse scattering intensities associated with $<110>$ (T2-type)
polarizations show little to no change in a [001] field, those associated with
$<100>$ (T1-type) polarizations are partially suppressed by the field at
temperatures below the Curie temperature \emph{T$_C$} $\sim 475$ K. Neutron
spin-echo measurements show that the diffuse scattering at (0.05,0,1) is
largely dynamic at high temperature and gradually freezes on cooling, becoming
mostly static at 200 K.
