Preparation and luminescent properties of MO{sub}2(M=Zr, Hf) with baddeleyite structure

摘要

Ti{sup}4+ activated zirconia (ZrO{sub}2) has been known as a phosphor, which has a broad emission band peaking at 490 nm and an afterglow lasting for several minutes. The visually detectable emission due to afterglow would be much improved bymeans of increasing a fluorescent intensity or forming traps that have suitable depth below a conduction band of ZrO{sub}2. We first examined the dependence of the luminescent intensity on coordination number for luminescent centers in three phases andtemperature prepared phosphors. 0.1% Ti{sup}4+ activated monoclinic ZrO{sub}2 has the highest emission intensity as compared to SrZrO{sub}3: 0.1%Ti and tetragonal ZrO{sub}2: 20%Y{sub}2O{sub}3, 0.1%Ti. The coordination number of Ti{sup}4+ in a monoclinicZrO{sub}2 is 7. Above the calcination temperature of 1200℃, luminescent intensity of the monoclinic ZrO{sub}2 phosphor sharply increased through phase transition. It was also observed that the persistence of afterglow depended upon the concentration ofthe traps created at high temperature. The traps were investigated by measuring thermoluminescence spectra. We discuss a mechanism of afterglow for the monoclinic ZrO{sub}2 phosphor. On the basis of these results, we tried to synthesize Ti{sup}4+activated hafnia (HfO{sub}2), and measured luminescent properties.