Cooperative luminescence of some trivalent lanthanide ions in cadmium fluoride crystals

Luminescence of Cadmium Fluoride Doped with Rare-earth Ions

“…Besides strong 5 D 3 -7 F j emission we also observed weak 5 D 4 -7 F j emission in CdF 2 -0.1% TbF 3 . The result that perturbation by neighboring Yb or Na leads to appearance of 5 D 3 -7 F j emission [11] and our emision spectra under 4f-4f and 4f-5d excitation undoubtedly points on fact, that the 5 D 3 levels of Tb 3+ locate very close to bottom of conduction band. So one may use the energy of 7 F j -5 D 3 transition (3.3 eV) as the energy distance from Tb 3+ ground state to bottom of conduction band.…”

“…For more than 0.05% of Tb, the author has only found the fluorescence transitions 5 D 4 -7 F j (with j = 0 to 6). In the presence of Yb or Na the fluorescence transitions starting from the excited level 5 D 3 were observed too [11]. Using 4f-5d excitation we clearly show that the 5 D 3 -7 F j emission is absent at lower Tb concentration also (see Fig.4).…”

“…From the absence of the luminescence from 5 D 3 level (see Fig.4) the energy distance from ground 7 F 6 level of Tb 3+ to bottom of conduction band should be larger than that of 7 F 6 -5 D 4 transition energy (2.5 eV) but should be less than that of 7 F 6 -5 D 3 (3.3 eV) energy. Terbium luminescence in CdF 2 was studied in [11]. For more than 0.05% of Tb, the author has only found the fluorescence transitions 5 D 4 -7 F j (with j = 0 to 6).…”

“…The terbium doping is introduced in the form of oxides (Tb 2 O 3 ) with nominal concentration of 1% [12]. The emission spectra of sample, illuminated by 350 nm light, exhibit a weak blue emission and a strong green emission in the spectral range 370-460 nm and 478-612 nm, which are assigned to 5 D 3 -7 F j and 5 D 4 -7 F j transitions of Tb 3+ , respectively [11]. However all emission bands, published in [12], were shifted near 10 nm to shorter wavelength side against to those measured in CdF 2 , CaF 2 , SrF 2 , BaF 2 .…”