Adjusting luminescence properties of ZnAl₂O₄:Mn²⁺(Mn⁴⁺), Li⁺ phosphors through cation substitution

Abstract

Abstract ZnAl 2 O 4 with a typical spinel structure is highly expected to be a novel rare‐earth‐free ion‐activated oxide phosphor with red emission, which holds high actual meaning for advancing phosphor‐converted light‐emitting diode (pc‐LED) lighting. Among the rare‐earth‐free activators, Mn 4+ ions have emerged as one of the most promising activators. Considering the price advantage of MnCO 3 generating Mn 2+ ions and the charge compensation effect potentially obtaining Mn 4+ ions from Mn 2+ ions, this research delves into a collection of ZnAl 2 O 4 :Mn 2+ (Mn 4+ ), x Li + ( x = 0%–40%) phosphors with Li + as co‐dopant and MnCO 3 as Mn 2+ dopant source prepared by a high temperature solid‐state reaction method. The lattice structure was investigated using X‐ray diffraction (XRD), photoluminescence (PL), and photoluminescence excitation (PLE) spectroscopy. Results suggest a relatively high probability of Li + ions occupying Zn 2+ lattice sites. Furthermore, Li + ion doping was assuredly found to facilitate the oxidization of Mn 2+ to Mn 4+ , leading to a shift of luminescence peak from 516 to 656 nm. An intriguing phenomenon that the emission color changed with the Li + doping content was also observed. Meanwhile, the luminescence intensity and quantum yield (QY) at different temperatures, as well as the relevant thermal quenching mechanism, were determined and elucidated detailedly.