Enhancement of luminescence via Mg substitution in self-activated Sr9(BN2)6

Commercially available phosphors rely heavily on rare earth (RE)-doped host materials, making the materials increasingly expensive. Addressing this challenge, we successfully developed novel RE-free self-activated phosphors Sr₉(BN₂)₆(SBN) and Sr₈Mg(BN₂)₆ (SMBN) through a simple one-step solid-state sintering process. Both possess the same cubic crystal structure. Replacing Sr²⁺ with Mg²⁺ ions effectively adjusts the vacancy, resulting in peculiar luminescence properties, such as blueshifting and broadening in the excitation peak, and high luminous efficiency in redshifted emission. It is speculated that the observed luminescence arises from the luminescent center formed by Sr1 and Sr2 vacancies (V_Sr1 and V_Sr2). The presence of Mg serves a dual purpose: it not only minimizes the trapping of electrons by intrinsic defects, improving the luminescence behavior, but also ameliorates the deliquescence of the SMBN sample when exposed to air, which is a guide to enhance the existing self-activated luminescent materials and explore new defect-related materials.