Novel red-emitting Cd2MgTeO6:Eu3+ phosphors with an abnormal thermal quenching for application in w-LEDs and potential fingerprint detection

A new series of red luminescent Cd 2 MgTeO 6 : x Eu 3+ ( x  = 0.5–50 mol%) phosphors was successfully synthesized through a high-temperature solid-phase reaction at 1000 °C. The synthesized phosphors were investigated for their phase purity, surface morphology , elemental distribution, and luminescence properties. Strong orange-red light emission (617 nm) was observed upon excitation at 398 nm, which was attributed to the electric dipole 5 D 0 - 7 F 2 transition of Eu 3+ . The optimal doping concentration was found to be x  = 20 mol%. Concentration quenching mechanism was identified as the interaction of near-neighbor ions. The chromaticity coordinates of all the Cd 2 MgTeO 6 :Eu 3+ samples were found to be located in the red region and were almost the same. The Cd 2 MgTeO 6 : 20 mol%Eu 3+ phosphors exhibited an unusual thermal quenching behavior, maintaining 102% of the initial intensity, thus possessing excellent thermostability. Moreover, the manufactured white light diode demonstrated a good color rendering index ( R a  = 89) with the coordinates of (0.344, 0.330) by the Commission International de L'Eclairage (CIE). Additionally, the Cd 2 MgTeO 6 : 20 mol%Eu 3+ phosphor was surface-functionalized with oleic acid (OA) (Cd 2 MgTeO 6 : 20 mol%Eu 3+ @OA) to aid in the identification of Level I-III fingerprint details with high resolution and contrast. Good visualization of the latent fingerprint (LFP) was observed on different substrates. Therefore, Cd 2 MgTeO 6 :Eu 3+ phosphors hold great promise for the visualization of w-LEDs and LFPs.