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Refractory metals have high melting points, with tungsten and rhenium the highest of all elements, and the other's melting points only exceeded by osmium and iridium, and the sublimation of carbon. These high melting points define most of their applications. All the metals are body-centered cubic except rhenium which is hexagonal close-packed.
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.
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
Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F), and the highest tensile strength. [26] Although carbon remains solid at higher temperatures than tungsten, carbon sublimes at atmospheric pressure instead of melting, so it has no melting ...
In contrast, nonmetals that form extended structures, such as long chains of selenium atoms, [26] sheets of carbon atoms in graphite, [27] or three-dimensional lattices of silicon atoms [28] have higher melting and boiling points, and are all solids, as it takes more energy to overcome their stronger bonding.
It has a melting point of 450 °C and a boiling point of 988 °C. Tellurium has a polyatomic (CN 2) hexagonal crystalline structure. It is a semiconductor with a band gap of 0.32 to 0.38 eV. Tellurium has a moderate ionisation energy (869.3 kJ/mol), high electron affinity (190 kJ/mol), and moderate electronegativity (2.1).
The hardness of osmium is moderately high at 4 GPa. Because of its hardness, brittleness, low vapor pressure (the lowest of the platinum-group metals), and very high melting point (the fourth highest of all elements, after carbon, tungsten, and rhenium), solid osmium is difficult to machine, form, or work.
NaK with 77% potassium is eutectic and has the lowest melting point of the NaK alloys at −12.6 °C. [ 78 ] Liquid sodium is used as a heat transfer fluid in sodium-cooled fast reactors [ 79 ] because it has the high thermal conductivity and low neutron absorption cross section required to achieve a high neutron flux in the reactor. [ 80 ]