Europium-containing inks are used to verify the security of printed items such as banknotes. They glow red under UV light, and forgeries can be detected by the lack of this red glow: Europium compounds and ink compositions containing the same (2003). Low-energy light bulbs contain a little europium to give a more natural light, by balancing the blue (cold) light with a little red (warm) light: Preparing A Luminescent Substance Activated By Europium – For Emitting Red Light (1969).
Europium-doped glass has been used as a laser material (Quartz Glass Doped With Europium And Production Thereof (1989), and in making thin super-conducting films (Super Conductive Thin Film Module – Stabilised Against Island Effect By Europium Sulphide Film (1972)).
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All patent information has been obtained from Espacenet (European Patent Office).