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Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in crystalline structure.. Allotropy or allotropism (from Ancient Greek ἄλλος (allos) 'other' and τρόπος (tropos) 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements.
The phase boundary between the different solid phases is drawn on a binary phase diagram, usually plotted as temperature versus percent iron. Adding some elements, such as Chromium , narrows the temperature range for the gamma phase, while others increase the temperature range of the gamma phase.
It has been described as slightly harder than graphite with a reflection color of grey to white. However, the existence of carbyne phases is disputed – see the article on chaoite for details. D-carbon: D-carbon was proposed by theorists in 2018. [33] D-carbon is an orthorhombic sp 3 carbon allotrope (6 atoms per cell).
The γ-phase can be described as a NaCl-type arrangement of two types of clusters, B 12 icosahedra and B 2 pairs. It can be produced by compressing other boron phases to 12–20 GPa and heating to 1500–1800 °C, and remains stable at ambient conditions.
Phase information is based on the work of G. C. Vezzoli, et al., as reviewed by David Young; as Young notes, "The literature on the allotropy of sulfur presents the most complex and confused situation of all the elements." [8] [9] Phase information are limited to ≤50 kbar and thus omitting metallic phases. [10]
The physical properties of carbon vary widely with the allotropic form. For example, graphite is opaque and black, while diamond is highly transparent. Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known.
The δ phase has more typical metallic character and is roughly as strong and malleable as aluminium. In fission weapons, the explosive shock waves used to compress a plutonium core will also cause a transition from the usual δ phase plutonium to the denser α phase, significantly helping to achieve supercriticality . [ 9 ]
There are six known distinct phases of solid oxygen. One of them is a dark-red O 8 cluster. When oxygen is subjected to a pressure of 96 GPa, it becomes metallic , in a similar manner to hydrogen , [ 14 ] and becomes more similar to the heavier chalcogens , such as selenium (exhibiting a pink-red color in its elemental state), tellurium and ...