A New High‐pressure Form of B2O3 and Inferences on Cation Coordination from Infrared Spectroscopy

A new crystalline variety of B 2 O 3 has been prepared at pressures above 22,000 atmospheres and above 400°C. The properties are listed. These moderate pressures also are sufficient to catalyze the crystallization of the more common hexagonal form from B 2 O 3 glass. Pressures, however, of up to 50,000 atmospheres will not convert GeO 2 quartz to GeO 2 rutile at room temperature. From the infrared absorption patterns of appropriate phases it can be shown that in coesite the tetrahedral coordination of Si 4+ (or Be 2+ in the model BeF 2 ‐coesite phase) must be unchanged. In the new form of B 2 O 3 , however, the coordination number must be substantially different from that in the common hexagonal B 2 O 3 .