Boron and the borides

Boron of purity 95-98% can be made by reducing B2O3 in a furnace with magnesium. High-purity boron can be obtained by the decomposition of the triiodide at 1 000 °C  

Each icosahedron is linked to others. The core of the icosahedron is a pair of parallel pentagons of boron atoms with opposite orientations these are shaded. The icosahedron is completed by boron atoms above and below the pair of pentagons. If we ignore slight irregularities in the real crystal, the unit has 20 faces, each consisting of an equilateral triangle of boron atoms of side 177 pm. 

The localization can be broken down when boron forms metallic borides. These are often metallic conductors, and can be thought of as alloys. Titanium diboride, TiB2, for example, is best made by heating boric and titanium oxides with carbon  

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Mahagin, D. E. and R. E. Dahl. 1977. Nuclear application of boron and the borides. In Boron and Refractory Borides, ed. V. I. Matkovich, pp. 613-622. Berlin, Germany Springer-Verlag. 

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