Nanostructured crystals of fluorite phases Sr1 − xRxF2 + x (R are rare-earth elements) and their ordering: IV. Study of the optical transmission spectra in the 2-17-μm wavelength range

Transmission spectra of two-component crystals of Sr1−x R x F2+x (R = Y, La-Lu; 0 ≤ x ≤ 0.5) in the 1–17-μm wavelength range were studied. The spectral characteristics of these crystals and of single-component crystals of MF2 (M = Ca, Sr, or Ba) and RF3 (R = La-Nd) were compared. The transmission cutoff of Sr1−x R x F2+x crystals is shifted to shorter wavelengths with increasing x. The same tendency is observed with the increasing atomic number R of rare-earth elements for two isoconcentration series of Sr1−x R x F2+x (x ∼ 0.10 and 0.28). This tendency is pronounced at large x. The transmission cutoff of Sr1−x R x F2+x crystals can be varied in the range of from 10.7 to 12.2 μm by changing their qualitative (R) and quantitative (x) composition. Hence, these crystals can be assigned to multicomponent fluoride optical materials with controlled optical characteristics. The Sr1−x R x F2+x crystals, where R = Ce-Sm, were shown to be promising materials for the design of selective optical filters in the 2–10-μm spectral range.