Thermally stimulated luminescence from single crystals of LiYF4 and its constituent fluorides

Thermally stimulated luminescence (TSL) from YF3, LiYF4 and LiYF4 (U4+) crystals has been investigated for the first time. While an undoped LiYF4 crystal exhibits very weak TSL, the emission from YF3 is found to be intense. On doping a LiYF4 crystal with uranium, its TSL output is observed to get considerably enhanced. The emission spectra recorded for all the crystals are found to be identical and characteristic of the constituent Y3+ ions. This is an important result which shows that in the process of TSL, U4+ ion behaves as a donor of excitation energy to Y3+ ions.