physica status solidi (b) 239, R7 (2003)
Emre Erdem, Rolf Böttcher, Hans-Christoph Semmelhack, Hans-Jürgen Gläsel, Eberhard Hartmann
Abstract
In our multi-frequency EPR study of Cr3+ doped PbTiO3 nanopowder samples with varying mean particle size, three paramagnetic Cr3+centres (C1, C2, C3) with different axial fine structure (FS) parameters are identified, with one of them (C1) being compatible with former literature measurements on bulk and ceramics samples carried out in the X band. The superposition model by Newman and Urban was applied to translate the FS data into local displacements inside the distorted oxygen octahedra of the PbTiO3 lattice. When going to nanopowder samples with mean particle size below a critical value, other than the centre C1 are no longer detectable. Instead, a new one (C4) appears, testifying a pronounced size effect. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
