Cathodoluminescence Emission-Spectra of ND-Doped CAF2

Rare-earth doping of CaF2 results in material which exhibits significant cathodoluminescence (CL) signals. Therefore CL measurements made on CaF2:Nd are reported for the temperature range 50 to 300 K with different excitation modulation frequencies. Since annealing treatment can be used to modify the spectra, the effects of annealing treatments of CaF2:Nd have been examined. Dopant levels used in the present study are 1.0, 0.1, and 0.01% Nd. All dopant levels exhibited different CL spectra with a combination of broad emission bands from the CaF2 host and lines from the Nd dopants. Broad bands are centred near 340 and 645 nm. The intense emission lines at 360, 389, and 419 are assigned D-4(3/2) to I-4(j) (j = 9/2 and 11/2) and P-2(1/2) to I-4(9/2), respectively. Other transitions to Nd transitions from 4D from D-4(3/2), (4)G(9/2), (4)G(5/2) and (4)G(5/2), (2)G(7/2) to I-4(j) (j = 9/2 to 15/2) are found. The 340 nm band is associated with the intrinsic emission, self-trapped exciton (STE) emission, of CaF2. The temperature dependence of the intensity of the emission band is discussed. The intrinsic emission band intensities decrease with increasing Nd content.