Anti-thermal quenching and self-reduction characteristics in Mn2+-doped LiScGeO4: Dual temperature effects on unique emission peak shifts

Mn-doped phosphors exhibiting self-reduction behavior have garnered significant attention in the study of luminescent materials due to the defects generated during the self-reduction process and their unique luminescent behavior. In this paper, LiScGeO 4 red phosphors activated by the self-reduction of Mn 4+ to Mn 2+ were synthesized by high-temperature solid-state reaction in an air atmosphere. The defects generated during the self-reduction process were leveraged to attain exceptional anti-thermal quenching characteristics, with luminescent intensity at a high temperature of 430 K being 1.23 times compared to that at room temperature of 300 K. In addition, a peculiar phenomenon occurred where the emission peak initially blueshifts and subsequently redshifts with the increasing temperature. This study includes an analysis of the Rietveld-refined lattice parameters and surface micromorphology of the samples. The theoretical energy gap of the perfect LiScGeO 4 matrix was calculated using density functional theory . Furthermore, the unique emission peak shift characteristics of Mn 2+ were elucidated through the interaction between Mn 2+ ions and the strength of the crystal field . Utilizing a defect model, the self-reduction mechanism and the anti-thermal quenching behavior were clarified. These findings will enhance the understanding of the effects of crystal defects and ion pair interactions on luminescent materials , and encourage further explorations of self-reducing phosphors to develop new high thermal stability phosphors for practical applications.