Double perovskite Ca2MgTeO6:Eu3+ red-emitting phosphors with high thermal stability for near UV/blue excited white LEDs

A series of Eu3+-doped double perovskite Ca2MgTeO6 (CMTO) red-emitting phosphors with high thermal stability were successfully prepared using the solid-state reaction at 1100 °C. The phase purity, surface morphology, and elemental mapping were investigated. Under near-ultraviolet (n-UV) (398 nm) and blue light (465 nm) excitation, the phosphors showed the strongest emission peak at 616 nm belonging to 5D0→7F2 transition. Besides, the ideal Eu3+ doping concentration was 0.30 mol. The major reason for the concentration quenching was the nearest neighbor ions interaction. More importantly, the CMTO:Eu3+ phosphors showed excellent thermal stability with a high value of activation energy (0.29 eV). The color purity of CMTO:0.30Eu3+ phosphor was up to 99.9% and the internal quantum efficiency (IQE) of CMTO:0.30Eu3+ was measured to be 53%. White light-emitting diodes (w-LEDs) based on the InGaN chip (λ = 398 nm) and GaN chip (λ = 465 nm) with high color rendering index (Ra) and low correlated color temperature (CCT) have been fabricated. Hence, the double perovskite CMTO:Eu3+ red phosphors have potential applications in the illumination field.