Photoluminescence properties of Ni2+-doped double perovskite A2MgTiO6 (A = La/Lu) phosphor with NIR-II emission for spectral analysis application

Near-infrared (NIR) phosphor is an attractive photoluminescent material, but the emission bandwidth of NIR phosphor is limited and the search for high-performance phosphor materials is still an urgent problem to be solved. In this work, the Ni²⁺-dopped A₂MgTiO₆ (A = La/Lu) phosphors were successfully synthesized for the first time by high-temperature solid-phase method. X-ray diffraction and scanning electron microscope (SEM) image confirmed the successful preparation of A₂MgTiO₆ (A = La/Lu): Ni²⁺ phosphors. Upon excitation at 408 nm, the A₂MgTiO₆ (A = La/Lu): Ni²⁺ phosphors exhibit broadband NIR emission from 1200 to 1600 nm with a full width at half-maximum (FWHM) of approximately 200 nm, originating from the ³T₂(³F) → ³A₂(³F) electron transition of Ni²⁺ ions. In addition, by comparing the luminescence characteristics and thermal activation energies of the La₂MgTiO₆: 1%Ni²⁺ and Lu₂MgTiO₆: 1%Ni²⁺ phosphors, it was found that the thermal stability of Lu₂MgTiO₆: 1%Ni²⁺ (80 %@425 K) is better than that of La₂MgTiO₆: 1%Ni²⁺ (33 %@425 K). Moreover, the transmission spectra of Lu₂MgTiO₆: 1%Ni²⁺ phosphor through ethanol and oil have been measured, indicating that Lu₂MgTiO₆: 1%Ni²⁺ phosphor has promising application in spectral analysis field.