Estimation of lattice site and valence of manganese impurities in PbTiO3ceramics by means of EPR

Abstract

The EPR spectra of Mn⁴⁺ and Mn²⁺ impurity ions have been studied in the tetragonal and cubic phase of PbTiO₃ ceramic powders. Most of the impurity ions are incorporated at regular lattice sites in crystalline regions of the ceramics. From a superposition model analysis it is deduced that Mn⁴⁺ is incorporated near the same off-centre position as Ti⁴⁺ whereas the Mn²⁺ is near the centre of the oxygen octahedron. The cubic phase observed by EPR is found to occur for reduced samples 40K below the phase transition temperature of PbTiO₃.