Using Ca2+ ions to induce the long afterglow and bluish white emission of red emitting phosphor Zn3Al2Ge2O10:Cr3+

Highlights: • Long afterglow of Zn₃Al₂Ge₂O₁₀:Cr³⁺ was caused by introducing Ca²⁺. • Bluish white emission of Zn₃Al₂Ge₂O₁₀:Cr³⁺ was created by introducing Ca²⁺. • Zn₃Al₂Ge₂O₁₀:Cr³⁺ can produce red emission in the range of 650–750 nm. The long afterglow and bluish white emission of red emitting material Zn₃Al₂Ge₂O₁₀:Cr³⁺ are induced by introducing Ca²⁺. Under excitation of 400 nm, Zn₃Al₂Ge₂O₁₀:Cr³⁺ can emit a red emission band at 694 nm in the range of 650–750 nm that is caused by ²E → ⁴A₂ transition of Cr³⁺. Under 262 nm excitation, Zn₃Al₂Ge₂O₁₀:Cr³⁺ can produce a weakly broad emission band in the range of 350–600 nm, and the emission intensity of Zn₃Al₂Ge₂O₁₀:Cr³⁺ can be enhanced by tuning the ratio of Ca²⁺ to Zn²⁺, especially, Zn₃Al₂Ge₂O₁₀:Cr³⁺ can present a bluish white emission and long afterglow properties by introducing Ca²⁺. The bluish white luminescence is caused by increasing the intrinsic defects (V^ʺ_Zn, V^ʺ_Ca and V^ʺ_O). And Ca vacancies can assist to stabilize the O vacancies; therefore, Zn₃Al₂Ge₂O₁₀:Cr³⁺ show the long afterglow characteristics. It enriched the luminescent properties of Zn₃Al₂Ge₂O₁₀:Cr³⁺ by introducing Ca²⁺, since Zn₃Al₂Ge₂O₁₀:Cr³⁺ shows different characteristics under different radiation excitation.