High quantum yield luminescence and magnetic properties of NaBa ₁₂ (BO ₃ ) ₇ F ₄ phosphors

Novel europium and phosphorus co-doped NaBa₁₂(BO₃)₇F₄ (NBBF) fluoroborates were synthesized for the first time. Structural analysis <i>via</i> X-ray powder diffraction indicates that the doping process initiates a change in the crystal symmetry, with the space group transitioning from <i>P</i>4₂<i>bc</i> to <i>Pbam</i>. Study of their photoluminescence properties revealed the appearance of red luminescence and a high quantum yield of up to 90-92%, which is higher in the case of the Eu-only-doped samples. Investigation of the magnetic properties uncovered a ferromagnetic contribution to the magnetic susceptibility and an unusually large effective magnetic moment associated with the europium ions. The high values of the effective magnetic moments and the high quantum yield were interpreted as evidence for the presence of nanoscale clusters. The combination of a high quantum yield and ferromagnetic properties makes Eu-doped NBBF interesting from the point of view of LED fabrication and magneto-optical applications.