Excitation Energy Transfer in CeF $_{3}$ Single Crystals Doped With Sr $^{2+}$

CeF₃ single crystals heavily doped with Sr²⁺ ions are grown by the micro-pulling-down (mu-PD) method. The deviation of the composition in as-grown crystals is found to be entirely negligible. Three dimensional emission-excitation spectra are measured in a wide temperature range of 5-300 K by using synchrotron radiation as an exciting light source. Two intense emission bands are observed at around 320 and 400 nm. The origin of these bands is discussed on the basis of the perturbation effects introduced by Sr doping. It is pointed out that the energy transfer takes place from Ce³⁺ sites to defect sites when the crystal is warmed from 5 to 300 K.