Hollington & Kyprianou

Europium is the most reactive of the rare earth elements.
Europium oxide (Eu2O3), one of europium's compounds, is widely used as a red phosphor in colour television sets and as an activator for yttrium-based phosphors.

In the new long-life low-energy compact fluorescents, Europium is responsible for the pleasant warmer color of the light. A mixture of europium compounds are coated onto the interior surface of the lamp and stimulated to glow by discharge through the low pressure gas in the tube.