Lead-gallium glasses and glass–ceramics doped with SiO2 for near infrared transmittance

• The stable lead–gallium glass was produced by admixture of SiO2.
• The effect of SiO2 content in PbGa-glass on transparence in NIR spectrum was studied.
• Transparent oxyfluoride glass–ceramics based on the lead-gallium glass was obtained.
• The low phonon BaF2 nanocrystallites were formed in the PbGa glass–ceramics.

Lead–gallium glasses, due to the absence of typical glass-forming components, are characterized by an increased tendency to crystallization. Despite this, they are interesting materials due to a shift of IR absorption edge up to 6–7 μm. The paper considers how the SiO2 dopant affects thermal stability and the UV–VIS and IR transmittance of lead-gallium glasses. The base lead-gallium glass (0.75PbO·0.25Ga2O3) was modified by the addition of 5, 10 and 15 mol% SiO2, respectively. DTA/DSC data showed that the glasses are characterized by the multi-stage crystallization, which is changed with the amount of silica doped. The XRD analysis confirmed that: (i) different forms of lead oxide crystallize after heat treatment of the glass, and (ii) the Ga2PbO4 phase is formed at higher temperatures.The silica admixture allowed inserting a few percent of BaF2 into the lead–gallium glass structure. It was found that a transparent glass–ceramic based on the lead-gallium glass with a low phonon barium fluoride phase can be obtained during the thermal treatment.The study of UV–VIS–IR transmittance shows that 10–15 mol% SiO2 in the lead-gallium glasses diminishes the absorption band in the range of 2.6–4 μm due to the presence of hydroxyl groups and simultaneously reduces transmittance in the range of 5–6.5 μm from 10 to 20%. Introduction of SiO2 to the glass results in the increase of transmittance in the shorter wavelength region and the UV-edge shift is observed. It was also confirmed that the BaF2 nanocrystallites exerts no effect on the transmittance of the spectrum analyzed.