Luminescence properties of Mn ~(2+)-doped Li _2ZnGeO _4 as an efficient green phosphor for field-emission displays with high color purity

摘要

Green emitting Li _2ZnGeO _4:Mn ~(2+) phosphors were synthesized through a high temperature solid-state reaction process. X-Ray diffraction, field emission scanning electron microscopy, photoluminescence (PL) and cathodoluminescence (CL) spectra were utilized to characterize the synthesized samples. Under UV and electron-beam excitation, the pure Li _2ZnGeO _4 sample shows a blue emission due to defects, while the Li _2ZnGeO _4:Mn ~(2+) sample exhibits a green emission corresponding to the characteristic transition of Mn ~(2+) (~4T _1 → ~6A _1). In particular, the CL intensity (brightness) of Li _2ZnGeO _4:Mn ~(2+) is higher than that of commercial green phosphor ZnO:Zn. In addition, the CL properties of Li _2ZnGeO _4:Mn ~(2+) phosphor, the dependence of CL intensity on accelerating voltage and filament current, the decay behavior of CL intensity under electron bombardment, and the stability of CIE chromaticity coordinates, have been investigated in detail. The results indicate that the as-prepared Li _2ZnGeO _4:Mn ~(2+) phosphor has a good CL intensity and CIE coordinate stability with green emission under low-voltage electron beam excitation. Therefore, Li _2ZnGeO _4:Mn ~(2+) is a promising green phosphor for application in full-color field-emission displays.