Comparative study of Ca4Y6(SiO4)6O:a phosphors prepared by sol-gel and dry methods (A = Pb2+, +Eu3+, Tb3+, +Dy3+)

Abstract

Ca₄Y₆(SiO₄)₆O:A (A = Pb²⁺, Eu³⁺, Tb³⁺, Dy³⁺) phosphors have been prepared by two methods: the sol-gel method and the conventional dry method. The crystallization processes and the luminescence characteristics of the phosphors were studied. The sol-gel method features low-temperature formation of the phosphor, leading to successful preparation of Pb²⁺-activated phosphors which could not be prepared by the dry method at high temperature. The (4f)^8–(4f)⁷(5d)¹ absorption band of Tb³⁺ and the charge-transfer (CT) band of Eu³⁺ have higher energies and narrower half-widths in the sol-gel-derived phosphors than in the phosphors prepared by the dry method, respectively. The Tb³⁺ and Dy³⁺ ions show stronger emission in the former than in the latter. Both the yellow-to-blue intensity ratio (Y: B) of Dy³⁺ and the red-to-orange intensity ratio (R : O) of Eu³⁺ in the sol-gel-derived phosphors are smaller than those for the phosphors derived by the dry method.