Tunable luminescence in co-doped Zn3Al2Ge2O10:Cr3+ by controlling crystal field splitting and nephelauxetic effect

Abstract

Ce3+/Dy3+/Tb3+/Eu3+/Mn2+ and Cr3+ ions co-doped Zn3Al2Ge2O10 phosphor were prepared by a high-temperature solid-state method. X-ray diffraction patterns prove the cubic phase structure of prepared Zn3Al2Ge2O10 phosphor. Emission, excitation spectra and decay curves confirm the tunable luminescence. Different degrees of the decrease of emission FWHM in Zn3Al2Ge2O10:0.02Cr3+,RE (RE = Ce3+, Dy3+, Tb3+, Eu3+) and Zn3Al2Ge2O10:0.02Cr3+,Mn2+ are observed. The reason of variable FWHM is the effect of crystal field splitting and nephelauxetic effect, and the nephelauxetic effect is dominant. Therefore, the emission FWHM decreases with the increasing concentration of Mn2+/Tb3+/Eu3+ in Zn3Al2Ge2O10:0.02Cr3+, and for Zn3Al2Ge2O10:0.02Cr3+,Ce3+ and Zn3Al2Ge2O10:0.02Cr3+,Dy3+, it is a constant. The variation of Zn3Al2Ge2O10:0.02Cr3+,Tb3+ is more obvious than that of Zn3Al2Ge2O10:0.02Cr3+,Eu3+, because Tb3+ ion has smaller electronegativity. Thus, the tunable luminescence of Cr3+ can be realized by co-doping different ions. And these phosphors have potential applications in light-emitting diodes for plant growth.