Structure and Properties of Silica Containing Aluminum and Phosphorus near the AIPO sub 4 join.

Refractive index and density have been measured for the system Al sub 2 O sub 3 -P sub 2 O sub 5 -SiO sub 2 near the AIPO sub 4 join. Compositions range down to 78% silica with ratios of aluminum to phosphorus from 0.5 to 2.0. As the join is approached at constant silica content, both properties decrease. The refractive index drops below that of pure silica while the mass density is slightly higher.