A New Silica-like Phase with Simple Cubic Structure

Abstract

GREIG¹ discovered that many metal oxide–silica systems exhibited liquid immiscibility at high temperatures. He found that the less siliceous liquid (as well as a range of adjacent compositions) usually devitrified in part, even on rapid quenching. As devitrification advanced the larger particles could be identified as cristobalite. However, the smaller particles, termed ‘dots’, could not be identified using the microscope. In the absence of any other positive evidence, and because they had a lower refractive index than that of the glass, it was concluded that the ‘dots’ were probably fine-grained cristobalite.