Developments in Ceramic Materials Research

Optical Fluoride and Oxysulfide Ceramics: Preparation and Characterization 67
transitions are measured in three ceramic samples at T=300 K using Shimadzu UV – 3101 PC
UV – VIS – NIR spectrometer (Figure 12).
Figure 12. Absorption spectra of the CaF 2: Er 3+ ceramic samples with different concentrations of the
Er 3+ ion measured at room temperature: CaF 2: Er 3+ (1%) – dark grey curve (В(2)2-06 sample) - 1, CaF 2:
Er 3+ (5%) – black curve (B(2)39-05 sample) - 2, CaF 2: Er 3+ (5%) – grey curve (В(1)3-06 sample) - 3.
As seen from the measured spectra the transitions in the samples with 5% concentration
of the Er 3+ ions is ∼ five – fold more intensive in comparison with the sample with 1%
concentration. But for the same mean concentration of Er 3+ (5%) in two samples the
absorption spectra are different. Thus, for the measured transitions in the B(2)39-05 ceramic
sample the absorption is larger than that in the В(1)3-06 one. It seems, the absorption
spectrum for the B(2)39-05 ceramic sample is measured in the range where mean
concentration of the Er 3+ ions is higher than in precursors (Figure 6). The ratio of the areas for
the 4 I15/2 → 4 I13/2 transition for the В(1)3-06 and В(2)2-06 ceramic samples with the 5% and
1% concentration of the Er 3+ ions is 5.76 that is more or less in an agreement with the
concentration of ErF3 in raw materials. Thus, preliminary chemical homogenization of raw
materials is required to obtain fluoride ceramics with uniform distribution of activator
impurities.
Fluorescence spectra at the 4 I11/2 → 4 I15/2 transition are measured under 810 nm CW laser
excitation in the CaF2:Er 3+ (5 mol. %) ceramic sample and the powdered ceramic sample of
the same composition at T=300 K (Figure 13). Comparison of the fluorescence spectra in the
ceramics and in the CaF2:Er 3+ (5 %) crystal shows small spectral shift to the shorter
wavelengths in the former and some modification in spectral shape in the CaF2: Er 3+ (5 mol.
%) ceramic sample, but the difference is not significant.