Regulation of the Phase Composition on Zn1.4Al1.2Ge0.4O4: Cr3+ Phosphor Luminescence Color

Abstract

We have proposed a type of Cr3+-doped Zn1.4Al1.2Ge0.4O4: Cr3+ phosphor by replacing ZnAl2O4: Cr3+ with germanium at different sintering temperatures in the high-temperature solid-phase method. Unlike the luminescence of common near-infrared ZnAl2O4 phosphors, Zn1.4Al1.2Ge0.4O4: Cr3+ phosphors have a more intense and persistent luminescence. At the same time, under the irradiation of 254 nm ultraviolet light, samples with different sintering temperatures show different luminescence colors. Phosphors exhibit long afterglow bluish white emission at sintering temperature below 1200 °C, and above 1200 °C (including 1200 °C), phosphors exhibit near-infrared long afterglow emission. This experiment systematically studies the effect of sintering temperature on Zn1.4Al1.2Ge0.4O4: Cr3+. The experimental results show that the abnormal blueish white emission of phosphors is related to the Zn2GeO4 formed during sintering. Zn2GeO4 is a self-luminous material with natural defects and shows a bluish white emission excited by ultraviolet rays. As the sintering temperature increases, the Zn2GeO4 phase in phosphors gradually disappears, Ge4+ ions enter the ZnAl2O4 lattice to replace Al3+ ions, and the emission color of Zn1.4Al1.2Ge0.4O4: Cr3+ phosphors changes from bluish white emission to near-infrared emission. Zn1.4Al1.2Ge0.4O4: Cr3+ phosphors showed different luminescence colors at different sintering temperatures, which enriched the luminescent properties of zinc aluminate-based phosphors.