A process of preparing a glass comprising: (a) heating a mixture of precursor chemicals to a melt temperature to form a melt, the melt being characterized in that quenching the melt at or above a threshold temperature results in a spinodal phase separation, and quenching the melt below the threshold temperature results in a droplet phase separation; and (b) quenching the melt at or above the threshold temperature in a preheated mold to form the glass composition having the spinodal phase separation.