This study investigated the liquid phase chemistry in Pb(Mg1/3Nb2/3)O-3-35 mol% PbTiO3 with excess PbO as previous studies suggested that the chemistry of the grain boundary phase may change {001} single-crystal growth. It has been shown that the chemistry of the liquid phase was dynamic as characterized in an analytical electron microscope. In fact, MgO was found to precipitate out of the system due to the saturation of MgO in the liquid, which in turn altered the liquid/solid surface energy. By changing the surface energy of the system, the matrix grains became more faceted, i.e. the frequency of {001} surfaces increased. This reduced the driving force for growth of the single crystal, which appears to be responsible for reducing the growth rate during annealing. Additional supporting evidence came from observing the effect of varying the PbTiO3 content.