METHOD OF MAKING A SILICA-TITANIA GLASS HAVING A TERNARY DOPED CRITICAL ZONE

In one aspect the disclosure is directed to a binary silica-titania glass blank having a CTE of 0±30 ppb/° C. or less over a temperature range of 5° C. to 35° C., and a doped silica-titania glass critical zone, wherein the dopant(s) are selected from the group consisting of aluminum oxide, and transition metal oxides, and amount of the dopant(s) is in the range of 0.05 wt. % to 8 wt. %. In various embodiments the dopants are selected from the group consisting of 0.25 wt. % to 8 wt. % Al2O3, 0.05 wt. % to 3 wt. % Nb2O5, and 0.25 wt. % to 6 wt. % Ta2O5, and mixtures thereof.