OTHER FORMS OF CARBON
Chaoite is a mineral believed to have been formed in meteorite impacts. It has been described as slightly harder than graphite with a reflection colour of grey to white. However, the existence of carbyne phases is disputed – see the entry on chaoite for details. Metallic carbon: Theoretical studies have shown that there are regions in the phase diagram, at extremely high pressures, where carbon has metallic character.[9] bcc-carbon: At ultrahigh pressures of above 1000 GPa, diamond is predicted to transform into the so-called C8 structure, a body-centered cubic structure with 8 atoms in the unit cell. This cubic carbon phase might have importance in astrophysics. Its structure is known in one of the metastable phases of silicon and is similar to cubane.[10] Superdense and superhard material resembling this phase has been synthesized and published in 2008.[11][12] bct-carbon: Body-centered tetragonal carbon proposed by theorists in 2010 [13][14] T-carbon: Every carbon atom in diamond is replaced with a carbon tetrahedron (hence 'T-carbon'). This was proposed by theorists in 2011.[15] M-carbon: Monoclinic C-centered carbon was first thought to have been created in 1963 by compressing graphite at room temperature. Its structure was theorized in 2006,[16] then in 2009 it was related [17] to those experimental observations. Many structural candidates, including bct-carbon, were proposed to be equally compatible with experimental data available at the time, until in 2012 it was theoretically proven that this structure is kinetically likeliest to form from graphite.[18][19] High-resolution data appeared shortly after, demonstrating that among all structure candidates only M-carbon is compatible with experiment.[20][21] There is an evidence that white dwarf stars have a core of crystallized carbon and oxygen nuclei. The largest of these found in the universe so far, BPM 37093, is located 50 light-years (4.7×1014 km) away in the constellation Centaurus. A news release from the Harvard-Smithsonian Center for Astrophysics described the 2,500-mile (4,000 km)-wide stellar core as a diamond,[22] and it was named as Lucy, after the Beatles' song "Lucy in the Sky With Diamonds";[23] however, it is more likely an exotic form of carbon. Prismane C8 is a theoretically-predicted metastable carbon allotrope comprising an atomic cluster of eight carbon atoms, with the shape of an elongated triangular bipyramid—a six-atom triangular prism with two more atoms above and below its bases.[
Chaoite is a mineral believed to have been formed in meteorite impacts. It has been described as slightly harder than graphite with a reflection colour of grey to white. However, the existence of carbyne phases is disputed – see the entry on chaoite for details. Metallic carbon: Theoretical studies have shown that there are regions in the phase diagram, at extremely high pressures, where carbon has metallic character.[9] bcc-carbon: At ultrahigh pressures of above 1000 GPa, diamond is predicted to transform into the so-called C8 structure, a body-centered cubic structure with 8 atoms in the unit cell. This cubic carbon phase might have importance in astrophysics. Its structure is known in one of the metastable phases of silicon and is similar to cubane.[10] Superdense and superhard material resembling this phase has been synthesized and published in 2008.[11][12] bct-carbon: Body-centered tetragonal carbon proposed by theorists in 2010 [13][14] T-carbon: Every carbon atom in diamond is replaced with a carbon tetrahedron (hence 'T-carbon'). This was proposed by theorists in 2011.[15] M-carbon: Monoclinic C-centered carbon was first thought to have been created in 1963 by compressing graphite at room temperature. Its structure was theorized in 2006,[16] then in 2009 it was related [17] to those experimental observations. Many structural candidates, including bct-carbon, were proposed to be equally compatible with experimental data available at the time, until in 2012 it was theoretically proven that this structure is kinetically likeliest to form from graphite.[18][19] High-resolution data appeared shortly after, demonstrating that among all structure candidates only M-carbon is compatible with experiment.[20][21] There is an evidence that white dwarf stars have a core of crystallized carbon and oxygen nuclei. The largest of these found in the universe so far, BPM 37093, is located 50 light-years (4.7×1014 km) away in the constellation Centaurus. A news release from the Harvard-Smithsonian Center for Astrophysics described the 2,500-mile (4,000 km)-wide stellar core as a diamond,[22] and it was named as Lucy, after the Beatles' song "Lucy in the Sky With Diamonds";[23] however, it is more likely an exotic form of carbon. Prismane C8 is a theoretically-predicted metastable carbon allotrope comprising an atomic cluster of eight carbon atoms, with the shape of an elongated triangular bipyramid—a six-atom triangular prism with two more atoms above and below its bases.[
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