Structure and photoluminescence properties of a rare-earth free red-emitting Mn(2+)-activated KMgBO3.

In this combined X-ray diffraction and photoluminescence study, the coordination environment of Mn(2+) and the photoluminescence of single Mn(2+) doped KMgBO3 phosphors were studied. Mn(2+) occupies Mg(2+) sites, which were coordinated by six O(2-). The strong absorption of KMgBO3:Mn(2+) was ascribed to the strong relaxation of spin and parity forbidden d-d transitions of Mn(2+). The emission bands were centered at 636 nm, regardless of the excitation wavelength and Mn(2+) doping concentration. Mn(2+) activated KMgBO3 could be efficiently excited with the excitation of Mn(2+) d-d transitions in the wavelength range of 300-475 nm. The red-shift of Mn(2+) emission was because of the strong crystal field environment of Mn(2+) 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.