Structure and Properties of Borate Glasses

The role of boron oxide in glass science is broad, spanning from borate glasses used as bioactive materials, sealing agents, dosimeters, and radiation shielding glasses, to an additive in chemically durable or nuclear-waste-immobilizing borosilicate glasses. The structure of borate glasses from pure boron oxide glass up to highly modified compositions is discussed in this chapter, covering the full range of borate chemical structures in glasses and melts. The boron anomaly, the conversion of trigonal borate units to tetrahedral borate units is introduced, and we outline the impact this has on the structure and properties of modified borate glasses. The factors influencing the equilibrium between three- and four-coordinated boron, such as modifier type and quantity, synthesis temperature, and the number of non-oxygen anions, are looked at to demonstrate the highly tuneable nature of borate glasses for diverse applications.