Achieving Real "Near Zero" Thermal Quenching: A Doping‐Controlled Order‐Disorder Transition in Sm3+‐Doped Double Perovskites

Abstract

Order‐disorder effects, which can be modulated by synthesis conditions, play a pivotal role in determining the structural, physical, and chemical properties of numerous materials. In this work, a doping‐controlled order‐disorder transition is proposed to regulate the A‐site cation ordering of AA'BB'O6 perovskites. Based on the cation‐anion elastic bonds model, a statistical model is presented to estimate the order‐disorder temperatures. The results suggest that the high coordination number of the dopants unexpectedly stabilizes the disordered structures. The minimization of thermal quenching, which leads to the destabilization of luminescence at high temperatures, represents one of the foremost challenges for phosphors utilized in LED illumination. The thermal stability of Sm3+ doped NaLaMgTeO6 orange–red phosphors varies significantly with different doping concentrations, which is associated with the doping‐controlled order‐disorder transition. Based on this phenomenon, the NaLaMgTeO6:2mol%Sm3+, 20mol%Sr2+ and NaLaScSbO6:2mol%Sm3+, 20mol%Sr2+ phosphors are systematically designed and synthesized, exhibiting a wide‐range real “near zero” thermal quenching. Within the 300–500 K, the deviation of the normalized luminescence intensity for NaLaMgTeO6:2mol%Sm3+, 20mol%Sr2+ and NaLaScSbO6:2mol%Sm3+, 20mol%Sr2+ phosphors is only 1.59% and 0.59%, respectively. The discovery of doping‐controlled order‐disorder transition unveils a new understanding of solid‐state physics/chemistry, and paves the way for designing and developing novel materials with enhanced stability.