Abstract
Barium hafnium–zirconium phosphate BaHf1-xZrx(PO4)2 (x=0–0.2), having the monoclinic KFe(SO4)2 (Yavapaiite) structure, is a broad-band UV-emitting phosphor. At room temperature, it has an emission peak maximum at approximately 356 nm under 30 kV peak molybdenum X-ray excitation. Compositions derived from 99% pure hafnia and having nominal values of x ∼ 0.01–0.05 demonstrate luminescence efficiencies that make BaHf1-xZrx(PO4)2 30% brighter than CaWO4 Hi-Plus. This efficiency is equal to that of a commercial M′–YTaO4 phosphor that emits at 330 nm. BaHf1-xZrx(PO4)2 is, thus, a potentially attractive candidate for use in medical diagnostic imaging systems. The lower X-ray absorption of BaHf1-xZrx(PO4)2, relative to that of UV-emitting M′–YTaO4, suggests that the title phosphor may be suitable for two-sided mammography screen applications. The synthesis conditions, X-ray excited luminescence, and effects of Eu, Sn, and Ti doping are discussed.