Selective doping of Ga20Ge20Se60 glass-ceramic matrix with lanthanum(III) selenide to increase its optical transparency in the 2–10 μm spectral range

To reduce optical losses due to scattering of radiation by crystals in Ga₂₀Ge₂₀Se₆₀ glass-ceramics, selective doping of the glass matrix with lanthanum(III) selenide is proposed. Samples of the (100-x)Ga₂₀Ge₂₀Se₆₀-xLa₄₀Se₆₀ (x = 0, 0.25, 0.625, 1.25, 2.5, 3.75, 5) glass- ceramics, which contain 40–57 vol.% of 3.0–4.6 μm sized sphalerite-type crystalline phases based on solid solutions of germanium(II, IV) selenides and gallium(III) selenide, are prepared. According to energy-dispersive spectroscopy data, lanthanum is concentrated in the glass matrix of glass-ceramics, and the distribution coefficient is 3.4 ± 0.6. An increase in the concentration of La in (100-x)Ga₁₀Ge₃₀Se₆₀–xLa₄₀Se₆₀ (x = 0, 1.25, 2.5) glasses leads to the rise of their refractive index by 0.023±0.008, when replacing 0.25Ga + 0.75Ge → 1La. For the first time, 97.5Ga₂₀Ge₂₀Se₆₀–2.5La₄₀Se₆₀ selenide glass-ceramics with a high volume content of micron-sized crystals and transparency of more than 50% in the 2–16 μm region are produced.