  The purpose of the present work is to report studies on structural phase
transition for PMN-xPT single crystal, with melt PbTiO3 composition around the
MPB (x = 0.35 mol %), using infrared spectroscopy technique. The study was
centered on monitoring the behavior of the stretching-(Nb-O), stretching-(Ti-O)
and stretching-(Mg-O) stretching modes as a function of temperature.
Singularities observed between 198 and 300 K suggested a possible coexistence
between the monoclinic and tetragonal phases, not revealed by others
techniques, for PMN-PT composition studied near MPB.
