Luminescence of divalent europium-doped calcium carbonate and oxalate

Divalent europium-doped calcium carbonate and oxalate were synthesized by m eans of co-precipitation, solid state reactions, and thermal decomposition processes under strictly controlled experimental conditions. Preliminary st udies of the synthesized phosphor materials showed that CaCO3:Eu2+ and CaC2 O4:Eu2+ have similar spectra, e.g, they both have broad band excitations an d emissions with peaks at 350 and 450 nm, respectively. Their luminescence properties are excellent to meet the requirement for an optical brightening agent (OBA) which is widely used in, for example, the paper industry. Furt hermore, these materials can be made at ambient to 500 degreesC which means a considerable lower cost compared with today's commercial blue phosphors that need annealing temperatures above 1000 degreesC. Blue luminescent CaCO 3:Eu2+ and CaC2O4:Eu2+ are therefore attractive alternatives for today's OB As. (C) 2001 Elsevier Science B.V. All rights reserved.