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

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.