Study of Pb<sub>0.5</sub>Cd<sub>0.25</sub>Lu<sub>0.25</sub>F<sub>2.25</sub> fluorite solid solution with congruent melting nature

For the first time, the optical, mechanical and conductive properties of the Pb0.5Cd0.25Lu0.25F2.25 crystalline matrix were studied in comparison with the crystals of the initial single-component fluorides. The short-wavelength transparency boundary of the three-component mixed crystal is determined by the presence of PbF2 in its composition, the IR boundary is naturally shifted up to 15 μm due to the presence of LuF3 in the composition. The refractive index of the studied solid solution n = 1.6889 on the λ = 0.6328 μm wavelength is lower than that of the PbF2 crystal due to the introduction of less polarizable components CdF2 and LuF3. For the three-component crystal, significant strengthening is observed, the microhardness HV = 2.5 GPa, which exceeds the hardness values of PbF2 and CdF2 by almost 40%. The electrical conductivity of Pb0.5Cd0.25Lu0.25F2.25 sdc at 500 K is 5.5 × 10−5 S/cm, which corresponds to the conductivity level of solid solutions M1−xLuxF2+x (M = Ca, Sr, Ba). The studied multicomponent fluoride material can be a promising crystalline medium for various photonic applications.