Study of surface acoustic phonon modes in relaxor Pb(Mg <inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf>

The surface acoustic phonon modes arising from 1:1 ordered, charged nanoclusters and the charge compensating disordered shells were analyzed in relaxor ferroelectric perovskite lead magnesium niobate (PMN). The size of the 1:1 ordered, charged nanocluster from the x-ray diffraction was estimated to be about 2nm. Surface acoustic Raman modes were detected in the frequency range 5-25 cm-1. The low frequency modes arised from two different interfaces, one between the 1:1 ordered charged nanoclusters and the surrounding positively charged nanoshell and another between the nanoshell and the outer disordered cubic phase of PMN.