Polymorphs of silicon dioxide: Difference between revisions
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* Common [[Quartz]] | * Common [[Quartz]] | ||
* amorphous forms (properties similar to: chalcedon, opal, obsidian, ...) <br>[[mechanosynthesis]] would allow for synthesis of '''pseudo amorphous configurations''' | * amorphous forms (properties similar to: chalcedon, opal, obsidian, ...) <br>[[mechanosynthesis]] would allow for synthesis of '''pseudo amorphous configurations''' <br> [[Neo-polymorph]]s | ||
== Especially interesting since unusually hard and dense == | == Especially interesting since unusually hard and dense == | ||
* [[Stishovite]] –– may be transitionable into other gemstomes with the same [[rutile structure]] forming [[pseudo phase diagram]]s | * [[Stishovite]] Mohs 8.5-9.0 tetragonal –– may be transitionable into other gemstomes with the same [[rutile structure]] forming [[pseudo phase diagram]]s | ||
* [[Seifertite]] –– (scrutinyte structure) | * [[Seifertite]] Mohs ~9 orthorhombic –– (scrutinyte structure) | ||
Both are metastable very hard and very dense. <br> | Both are metastable very hard and very dense. <br> | ||
They may not be very resilient against high temperatures. | They may not be very resilient against high temperatures. | ||
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== Other polymorphs of SiO<sub>2</sub> == | == Other polymorphs of SiO<sub>2</sub> == | ||
* {{wikitodo| | * {{wikitodo|Better overview over the known polymorphs (structure images?) and in how far they may be able to form compatible transitions in some directions.}} | ||
* https://en.wikipedia.org/wiki/Category:Silica_polymorphs | |||
---- | |||
'''Basic low density polymprphs:''' | |||
* https://en.wikipedia.org/wiki/Keatite Mohs 5.75 tetragonal | |||
* https://en.wikipedia.org/wiki/Tridymite Mohs 7 orthorhombic (high temp modification) | |||
* https://en.wikipedia.org/wiki/Cristobalite Mohs 6-7 tetragonal <br>(& high temp β-cristobalite cubic - diamond like structure) | |||
* https://en.wikipedia.org/wiki/Melanophlogite Mohs 6.5-7.0 cubic or tetragonal | |||
* https://en.wikipedia.org/wiki/Coesite Mohs 7.7-8.0 monoclinic | |||
---- | |||
'''Exotic stuff:''' | |||
* https://en.wikipedia.org/wiki/Chibaite Mohs 7 cubic structure chalrate: <br> | |||
* https://en.wikipedia.org/wiki/2D_silica | |||
* CaCl<sub>2</sub>-type and α-PbO<sub>2</sub>-type (high pressure phases) <br>[https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002GL016722 2003 – Stability of CaCl<sub>2</sub>-type and α-PbO2-type SiO<sub>2</sub> at high pressure and temperature determined by in-situ X-ray measurements] | |||
== Related == | == Related == | ||
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* [[Silicon]], [[Oxygen]] | * [[Silicon]], [[Oxygen]] | ||
* [[Gemstone like compound]] | * [[Gemstone like compound]] | ||
* [[Neo-polymorphs]] | |||
Latest revision as of 10:39, 29 September 2025
More commonly known SiO2 gemstones
- Common Quartz
- amorphous forms (properties similar to: chalcedon, opal, obsidian, ...)
mechanosynthesis would allow for synthesis of pseudo amorphous configurations
Neo-polymorphs
Especially interesting since unusually hard and dense
- Stishovite Mohs 8.5-9.0 tetragonal –– may be transitionable into other gemstomes with the same rutile structure forming pseudo phase diagrams
- Seifertite Mohs ~9 orthorhombic –– (scrutinyte structure)
Both are metastable very hard and very dense.
They may not be very resilient against high temperatures.
Other polymorphs of SiO2
- (wiki-TODO: Better overview over the known polymorphs (structure images?) and in how far they may be able to form compatible transitions in some directions.)
- https://en.wikipedia.org/wiki/Category:Silica_polymorphs
Basic low density polymprphs:
- https://en.wikipedia.org/wiki/Keatite Mohs 5.75 tetragonal
- https://en.wikipedia.org/wiki/Tridymite Mohs 7 orthorhombic (high temp modification)
- https://en.wikipedia.org/wiki/Cristobalite Mohs 6-7 tetragonal
(& high temp β-cristobalite cubic - diamond like structure) - https://en.wikipedia.org/wiki/Melanophlogite Mohs 6.5-7.0 cubic or tetragonal
- https://en.wikipedia.org/wiki/Coesite Mohs 7.7-8.0 monoclinic
Exotic stuff:
- https://en.wikipedia.org/wiki/Chibaite Mohs 7 cubic structure chalrate:
- https://en.wikipedia.org/wiki/2D_silica
- CaCl2-type and α-PbO2-type (high pressure phases)
2003 – Stability of CaCl2-type and α-PbO2-type SiO2 at high pressure and temperature determined by in-situ X-ray measurements