Photoluminescence and electron paramagnetic resonance properties of a potential phototherapic agent: MMgF4 :Gd3+ (M = Ba, Sr) sub-microphosphors.

Novel narrow band UVB-emitting phosphors, BaMgF4 :Gd3+ and SrMgF4 :Gd3+ phosphors, were synthesized using a co-precipitation synthesis method. X-Ray diffraction analysis was carried out to confirm compound formation, phase purity and crystallinity of the phosphor. At 274 nm excitation, phosphors show a sharp narrow band emission at 313 nm that can be assigned to 6 P7/2  → 8 S7/2 transition of the Gd3+ ion. With increasing dopant concentration, intensity enhances and then decreases after a certain concentration, which is an indication of concentration quenching taking place in the phosphor. Scanning electron microscopy images of the phosphor show agglomerated particles in the sub-micron range. Particles range in size from 600 to 800 nm. Electron paramagnetic resonance studies of the phosphors were carried out to detect radicals present in the prepared phosphor. With narrow band UVB emission, phosphor seems to be a good candidate for UV phototherapy application.