METHOD FOR OBTAINING OPTICAL SITALL Russian patent published in 2015 - IPC C03C10/12 

FIELD: chemistry.

SUBSTANCE: composition of initial glass includes SiO₂, P₂O₅, Al₂O₃, Li₂O, MgO, ZnO, CaO, BaO, TiO₂, ZrO₂, As₂O₃ and additionally Sb₂O₃ in quantity 1-3 wt %. Method for obtaining sitall includes preliminary thermal processing of mixture of raw materials at temperature 1200-1250°C for 4-6 hours with further grinding of formed cake in ball mill until homogeneous finely disperse mixture is formed. Melting of initial glass is carried out in electric furnaces in corundum crucibles at temperatures not higher than 1590±2°C. Sitallisation of material is performed in two-step mode: heating and exposure at temperature of formation of crystallisation nucleating centres 620-660°C for 4-5 hours and exposure at temperature of crystal growth 700-770°C for 10-20 hours.

EFFECT: obtaining sitall, optically transparent in visible spectrum area, with stable near-zero TCLE value in wide temperature interval.

3 ex, 2 dwg