Boron
EPA Designation Candidate
EPA Classification Chemical
EPA Levels n/a
Alternative Names none
Sources not available
Boron is a chemical element with chemical symbol B and atomic number 5. Because boron is produced entirely by cosmic ray spallation and not by stellar nucleosynthesis,[8] it is a low-abundance element in both the solar system and the Earth's crust.

Overview

not available Boron is a chemical element with chemical symbol B and atomic number 5. Because boron is produced entirely by cosmic ray spallation and not by stellar nucleosynthesis,[8] it is a low-abundance element in both the solar system and the Earth's crust. Boron is similar to carbon in its capability to form stable covalently bonded molecular networks. Even nominally disordered (amorphous) boron contains regular boron icosahedra which are, however, bonded randomly to each other without long-range order.[19][20] Crystalline boron is a very hard, black material with a high melting point of above 2000 °C. It exists in four major polymorphs: α, β, γ and T. Whereas α, β and T phases are based on B12 icosahedra, the γ-phase can be described as a rocksalt-type arrangement of the icosahedra and B2 atomic pairs.[21] It can be produced by compressing other boron phases to 12-20 GPa and heating to 1500-1800 °C; it remains stable after releasing the temperature and pressure. The T phase is produced at similar pressures, but higher temperatures of 1800-2200 °C. As to the α and β phases, they might both coexist at ambient conditions with the β phase being more stable.[21][22][23] Compressing boron above 160 GPa produces a boron phase with an as yet unknown structure, and this phase is a superconductor at temperatures 6-12 K

Uses

The major industrial-scale uses of boron compounds are in sodium perborate bleaches, and the borax component of fiberglass insulation. Boron polymers and ceramics play specialized roles as high-strength lightweight structural and refractory materials. Boron compounds are used in silica-based glasses and ceramics to give them resistance to thermal shock. Boron-containing reagents are used for as intermediates in the synthesis of organic fine chemicals. A few boron-containing organic pharmaceuticals are used, or are in study. Natural boron is composed of two stable isotopes, one of which (boron-10) has a number of uses as a neutron-capturing agent.

Health Effects

No known effects.