Structure and luminescent properties of CaCO3:Eu3+ phosphors prepared in ethylene glycol-water mixed solvent

A series of CaCO3:Eu3+ phosphors with novel morphology were successfully synthesized in an ethylene glyco-l-water system by a simple carbonation method without using any surfactant, catalyst, or template. It is indicated that the ratio of mixed solvent and reaction temperature play an important role in the morphology, structure, and the luminescence properties of the CaCO3:Eu3+ phosphors. Various morphologies of CaCO3:Eu3+ phosphors, such as rod-like, polyhedron, dendritic, spindle, and rhombohedral, can be obtained only by just adjusting the ratio of mixed solvent or reaction temperature. In addition, high ratio of ethylene glycol in mixed solvent and low temperature favor the formation of metastable vaterite phase. Furthermore, the photoluminescent intensity, the ratio of red-orange of Eu3+ ions change with the morphological and structural changes of the CaCO3:Eu3+ crystal, which is attributed to the variation of the environment around Eu3+ ions. The symmetry and surrounding environment of Eu3+ ions in the CaCO3 matrix are analyzed by Judd Ofelt theory. Finally, the possible formation mechanism of CaCO3:Eu3+ phosphors has been also discussed.