Luminescence spectra of SrTiO3 : Mn4+

Manganese doping of SrTiO3 results in structured luminescence consisting of narrow zero-phonon (ZPL) R-line of Mn4+ (E-2 --> (4)A(2)) peaking at 13 826.8 cm(-1) (T = 15 K) and vibrational sidebands. ZPL of Mn4+ exhibits an unusually large shift with temperature, which follows the reciprocal dielectric constant. The excitation spectrum of Mn4+ consists of two broad bands at 18 182 and 23 585 cm(-1), which are assigned to (4)A(2) --> T-4(2) and (4)A(2) --> T-4(1) transitions, respectively. The Mn4+ luminescence intensity decreases with time at steady-state excitation with photon energy higher than 1.9 eV at temperatures lower than 100 K. The behavior of Mn4+ luminescence is discussed taking into account the specificity of impurity-lattice interaction and the possibility of off-center behavior of d(3) ions in ABO(3) perovskites with soft TO modes. (C) 2000 Elsevier Science B.V. All rights reserved.