White sapphire
Terminology
"White sapphire" (meaning clear transparent colorless) because we want to focus on perfect crystals without any color giving impurities.
A base material for gemstone metamaterial technology would be perfectly impurity free and colorless clear.
Just "sapphire" usually refers to sapphires with impurities (iron and titanium ions replace aluminum ions) causing a blue to black color.
Also called lecosapphire or leukosapphire (may be more prevalent in German).
Advantages of this gem
- very hard material (Mohs 9 – defining mineral), very high heat conductivity
- made out of the extremely common element aluminum (more common than carbon in diamond or moissanite)
Possibly helpful on the Moon with carbon being scarce. - like moissanite sapphire is thermodynamically stable not just metastable like diamond thus very heat resistant
- Crystal structure: trigonal – Not as high symmetry as cubic but still good.
Maybe look at metastable Al2O3 polymorphs at the eventual cost of somewhat less heat resistance?
Related
- Tistarite Ti2O3 has the same structure. => neo-polymorph series?
- Gemstone like compounds with high potential – Gemstone like compounds
- Corundum structure – Simple crystal structures of especial interest
- Aluminum oxides
- Moissanite is also an extremely heat resistant base material.
- Diamond is much less heat and oxidation resistant.
- Both diamond and moissanite have higher crystal structure symmetry than leukosapphire
Polymorphs
Deltalumite Al2O3 (δ form of corundum, polymorph of sapphire) – tetragonal – Mohs ? –
Paper: "Deltalumite, a new natural modification of alumina with spinel-type structure"
- Researchgate Jannuary 2019 [1]
- Researchgate December 2020 [2]
- (semanticscholar) << Images!
How to spell this ??
- Delt-alumite?
- Delta-lumite?
- Delta-alumite?
External links
Wikipedia
- materialsproject.org [3]
- mineralienatlas (de) [4]
- Strukturtypendatenbank uni-freiburg: [5]
- Wikidata leukosapphire: https://www.wikidata.org/wiki/Q3831236
