Nonradiative relaxation processes in V 3+ doped halide and oxide lattices

Abstract

The nonradiative relaxation properties of the near-infrared luminescence from V 3+ in a series of 10 fluoride, chloride, bromide and oxide lattices are investigated. Nonradiative multiphonon relaxation processes are strongly dependent on the host lattice. The chemical nature of the lattice has a bigger effect than structural differences. In Al 2O 3 nonradiative processes dominate down to 2 K, whereas in the various chloride lattices luminescence quenching sets in above 300 K. The temperature dependence of the nonradiative rate k nr for all lattices is reasonably reproduced by a single configurational coordinate model. k nr(0) values thus obtained are compared to theoretical values obtained from calculated electronic factors R. The experimental values deviate by many orders of magnitude from the theoretical estimates. Nonlinear coupling (for chloride and bromide lattices) and anharmonicity (for fluoride and oxide lattices) are discussed as possible sources of the discrepancies. An empirical correlation of the luminescence quenching temperature with the Huang-Rhys factor S and the number p of vibrational quanta created in the relaxation process is presented.