Decay dynamics of europium excited states in bioactive glasses

Optical probes of solution-produced glasses yield valuable information about the local structure and dynamics of the host glass systems. We report lifetime results for europium excited states in a series of sol-gel-produced bioactive glasses with the composition CaxP0.06Si0.94-xO2 (0.11 < x <0.35). The excited state lifetimes are very narrowly distributed about a mean value, leading to nearly single exponential decay curves. A rate equation model is used to study the effects of calcium concentration and temperature on the decay rates. While the presence of calcium in the glass samples greatly enhances the luminescence, over the concentration range tested, no significant difference in the decay times was measured. Over the temperature range 77-300 K about 20% and 30% increases in the decay rates of the D-5(0) and D-5(1) levels were measured, respectively. (C) 2008 Elsevier B.V. All rights reserved.