A new high-efficiency UV-emitting X-ray phosphor, BaNf1-xZrx(PO4)2

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 similar to 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. (C) 2000 Academic Press.