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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.
Plutonium in the delta (δ) phase [8] normally exists in the 310 °C to 452 °C range but is stable at room temperature when alloyed with a small percentage of gallium, aluminium, or cerium, enhancing workability and allowing it to be welded in weapons applications. The δ phase has more typical metallic character and is roughly as strong and ...
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).
A historic phase diagram of sulfur. A phase diagram from 1975, presenting data through 1970. The ordinate is pressure in kilobars (kbar). and the abscissa is temperature in kelvins (K). (The temperatures 200, 400, 600, and 800 K correspond to the approximate temperatures of −73, 127, 327, and 527 °C, respectively.)
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.
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 ...
Upon sublimation at 616 °C, the gas phase arsenic molecules lose this packing arrangement and form small clusters of As 4, As 2, and As, though As 4 is by far the most abundant in this phase. [1] If these vapors are condensed swiftly onto a cold surface (<200 K), solid yellow arsenic (As 4 ) results due to the lack of energy required to form ...