Densities of SiO 2 ‐Al 2 O 3 Melts

The densities of binary aluminosilicate melts were measured X‐radiographically as a function of Al 2 O 3 , concentration between 1800° and 2000°C. Within this temperature range, the density curves vary linearly and are parallel from fused SiO 2 to ≊30 to 45 mol% Al 2 O 3 , depending on the temperature. At higher Al 2 O 3 contents, negative deviation from linearity increases with increasing temperature. Recent supplementary research efforts on various aspects of the system SiO 2 ‐Al 2 O 3 indicate that the changing coordination and structural role of the aluminum ion may be a primary factor in determining the shapes of the density curves.