Luminescent properties of Eu²⁺ and Ho³⁺ co-doped CaGa₂S₄ phosphor

A new persistent yellow-emitting phosphor CaGa₂S₄: Eu²⁺, Ho³⁺ was prepared by a solid-state method. The luminescence properties, including thermoluminescence (TL) glow curve and its spectral decomposition, as well as the long decay time curve, were studied. The results revealed that a new trapping level with a suitable depth was created due to co-doped Ho³⁺, which led to the long afterglow at room temperature. Trapping depths were evaluated by a TL glow curve fitted by a general order kinetics formula. A mechanism for the long-duration phosphorescence from Eu²⁺ in CaGa₂S₄: Eu ²⁺, Ho³⁺ was also proposed.