Mn2+ luminescence of Gd(Zn,Mg)B5O10 pentaborate under high pressure†
The results of X-ray diffraction studies of the Gd(Mg0.95−x,ZnxMn−0.05)B5O10 down-converting phosphor as a function of Mg–Zn composition are presented. The lattice parameters and unit cell volumes of GdMg0.95−xZnxMn0.05B5O10 pentaborates are examined. The relationships between the structure and optical properties of these materials are explicated based on the results of theoretical calculations of the energy structure. The effect of pressure on the luminescence of Mn2+ in this system was studied up to ca. 32 GPa. The observed quenching of Mn2+ luminescence is due to the crossing of the emitting 4T1g level with the non-emitting 2T2g state. This crossing sets a long-wavelength limit on the possibility of observing the emission of Mn2+ ions, which is around 850 nm.