FLUORESCENCE PROPERTIES AND STABILIZATION OF Ce³⁺ AND Tb³⁺ CODOPED CALCIUM CARBONATE PHOSPHOR TREATED IN AMMONIUM PHOSPHATE SOLUTION

Abstract

This paper reports the fluorescence properties and stabilization of Ce³⁺ and Tb³⁺ codoped calcium carbonate phosphor which was treated in an ammonium phosphate solution. The reaction rate of the phosphor (Ce³⁺ and Tb³⁺ codoped calcium carbonate, CaCO₃:Ce³⁺, Tb³⁺) when treated for 60 minutes in (NH₄)₃PO₄ solution was approximately 40 mass%. Amorphous calcium phosphate (ACP) and dicalcium phosphate dihydrate (DCPD), which was obtained by the crystallization of ACP, were seen to adhere to the phosphor surface. The emission intensity of the phosphor treated for 60 minutes rose by 1.7 times that of the original phosphor and gently decreased for about 60 days. The ACP adhered on the phosphor surface was in the form of ultrafine particles and was emitted by the inclusion both Ce³⁺ and Tb³⁺ ions. It is thought that the increase of the emission intensity of the phosphor adhered ACP is based on the emission from both ACP and the phosphor.