Abstract: The mechanism of B site ordering and disordering in Lead Magnesium Niobate (PMN) was examined by heat treatment at different annealing time The B-site structural ordering characteristics were exposed by selected area electron diffraction (SAED) and high resolution electron microscopy (HREM) By analyzing the different types of chemical bonds in the BO₆ network by the Raman spectroscopy, it was demonstrated that ordered domains in PMN are Mg rich region while disordered domains are Mg poor (or Nb-rich).

Key words: relaxor ferroelectrics, order disorder structure, chemical bond