X-Band EPR Studies of Ferroelectric Lead Titanate (PT), Piezoelectric Lead Magnesium Niobate (PMN), and PMN/PT Powders at 10 and 85 K

Abstract

X-band EPR spectra of lead titanate (PT) and lead magnesium niobate (PMN) powders prepared by different synthetic methods and a PMN/PT powder of the composition 0.9 PMN/0.1 PT were obtained at 85 and 10 K. Several EPR signals due to adventitious Fe 3+ ion impurities, a signal due to the Ti 3+ ion, and a signal due to the Pb 3+ ion are observed for PT, PMN, and PMN/PT powders. The EPR signals observed at g = 2.0 and 6.0 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of lead titanate with axial symmetry. The EPR signals observed at g = 1.99 and 4.25 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of PMN and 0.9 PMN/0.1 PT materials with cubic and rhombic symmetries, respectively. The sharp EPR signal observed at g = 1.94 is assigned to Ti 3+ ion for PT and 0.9 PMN/0.1 PT powders. In addition, a broader EPR signal at g = 2.28−2.30 for PMN obtained by the molten salt method is assigned to axial Pb 3+ ion sites in this PMN material. EPR results obtained here for the Fe 3+ ions in the B-sites of the PMN materials, in particular, suggest that both cubic and rhombic symmetry sites corresponding to a range of Nb(OMg) x (ONb) 6 - x site configurations exist in the PMN. These EPR results indicate that PMN likely exists with partial B-site cation (Mg/Nb) ordering in the perovskite lattice structure.