Structure and photoluminescence properties of a rare-earth free red-emitting Mn2+-activated KMgBO3

Abstract

In this combined X-ray diffraction and photoluminescence study, the coordination environment of Mn²⁺ and the photoluminescence of single Mn²⁺ doped KMgBO₃ phosphors were studied. Mn²⁺ occupies Mg²⁺ sites, which were coordinated by six O²⁻. The strong absorption of KMgBO₃:Mn²⁺ was ascribed to the strong relaxation of spin and parity forbidden d–d transitions of Mn²⁺. The emission bands were centered at 636 nm, regardless of the excitation wavelength and Mn²⁺ doping concentration. Mn²⁺ activated KMgBO₃ could be efficiently excited with the excitation of Mn²⁺ d–d transitions in the wavelength range of 300–475 nm. The red-shift of Mn²⁺ emission was because of the strong crystal field environment of Mn²⁺ afforded by KMgBO₃. The potential applications of the phosphors have been pointed out based on their absorption spectra, excitation and emission spectra, thermal quenching properties, and decay properties.