We request 6 days of HRPD time in order to study the structures on the tetragonal side of the lead zirconate-titanate (PZT) phase diagram, a region that has so far been rather neglected. Our objective in this is to establish whether this region is actually a pure single-phase region and whether there exists local disorder in the structure. Furthermore, we wish to study the high-temperature cubic phase at selected compositions, since recent synchrotron radiation measurements have led to the claim that the cubic phase is actually disordered.