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Crystalline boron is a hard, black material with a melting point of above 2000 °C. Crystalline boron is chemically inert and resistant to attack by boiling hydrofluoric or hydrochloric acid . When finely divided, it is attacked slowly by hot concentrated hydrogen peroxide , hot concentrated nitric acid , hot sulfuric acid or hot mixture of ...
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Hexagonal boron nitride (point group = D 3h; ... Little is known on melting behavior of boron nitride. It degrades at 2973 °C, but melts at elevated pressure.
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Crystalline boron is a very hard, black material with a high melting point and exists in many polymorphs: Two rhombohedral forms, α-boron and β-boron containing 12 and 106.7 atoms in the rhombohedral unit cell respectively, and 50-atom tetragonal boron are the most common. Boron has a density of 2.34 −3. [17]
Amorphous powder boron and polycrystalline β-rhombohedral boron are the most common forms. The latter allotrope is a very hard [n 1] grey material, about ten percent lighter than aluminium and with a melting point (2080 °C) several hundred degrees higher than that of steel. [6]
This is a list of the various reported boiling points for the elements, with recommended values to be used elsewhere on Wikipedia. For broader coverage of this topic, see Boiling point . Boiling points, Master List format
Melting point: 450 °C (842 °F; 723 K) (trigonal) 510 °C (tetrahedral) ... Boron trioxide or diboron trioxide is the oxide of boron with the formula B 2 O 3. It is ...