Rutile
Overall rutile is good base material for gemstone metamaterial technology for large scale construction.
Rutile is a polymorph of titanium dioxide (TiO2)
It may be of peculiar interest because:
- it contains the element titanium (Ti) whitch is one of the more abundant elements in earth crust.
- it has a reasonably high hardness (Mohs 6.0 to 6.5)
- it features a reasonably simple (tetragonal) crystal lattice (in fact it's the defining minearal for the rutile structure)
- with the rutile structure it features the exact same structure as stishovite (a peculiarly interesting SiO2 polymorph) but given it occurs naturally in high quantities (unlike stishovite) it likely has a higher thermodynamic stability. That is: it's less prone to diffusion into a more stable polymorph at higher temperatures.
Given both rutile and stishovite feature the same crystal structure it may be possible to mechanosynthesize checkerboard neo-polymorphic transitions by replacing some Ti with with Si in a regular pattern.
Polymorphs of (TiO2)
rutile (Mohs 6.0 to 6.5)
anatase (Mohs 5.5 to 6.0).
It also has a simple tetragonal crystal lattice but different from the rutile structure
in that the unit cell is a bit bigger (and sparser?).
brookite (Mohs 5.5 to 6.0).
It also has a bigger unit cell than rutile and has the lower orthorombic crystal structure symmetry
which perhaps may make it a bit less interesting as a potential base material.
tistarite (Mohs 8.5).
Trigonal crystal structure.
High pressure modification of TiO2 – same structure as ZrO2 Baddeleyite (monoclinic Baddeleyte becomes "cubic zirconia" with some other metals added):
akaogiite (mineralienatlas)
High pressure modification isostructural to α-PbO2 (scrutinyite structure) ans isostructural to seifertite – orthorhombic dipyramidal
srilankite (mineralienatlas)
Misc
- All (TiO2) polymorphs have a high refractive index
Potential elements for controlled mechanosynthetic substitution for doping or the creation of neo-polymorphs include:
- iron Fe (extremely common) – a common natural impurity of rutile
- niobium Nb (less common) – a common natural impurity of rutile
- tantalum Ta (extremely rare) – a common natural impurity of rutile
- possibly silicon Si – since it forms an oxide with exactly the same crystal structure as rutile (stishovite)
Elements that also shares the rutile structure:
- the germanium dioxide mineral argutite (wikipedia) (germanium is one of the more rare elements though)
- the tin dioxide minearl cassiereite (wikipedia) (tin is a bit more common than germanium)
- ...
Interplanetary applications (Moon)
Titanium is supposedly especially abundant on the moon.
So future gem-gum products on the moon may feature a lot of rutile, anatase, brookite, (or other titanium based gemstones) for structural parts.
Related
The emenets in the Silicon group like to kake on rutile structure too.
A lot of neo-polymorphs may become possible by swapping out some of the titan for other compatible elements.
- Rutile structure
- Stishovite – rutile isostructural polymorph of quartz SiO2 with Mohs 8.5 to 9.5 – eventually good for making transition neo-polymorphs
External links
Wikipedia:
- https://en.wikipedia.org/wiki/Rutile (tetragonal | mohs 5.0 to 6.5 | 4.23 g/ccm)
- https://en.wikipedia.org/wiki/Anatase (tetragonal | mohs 5.5 to 6.0 | 3.79 – 3.97 g/ccm)
- https://en.wikipedia.org/wiki/Brookite (orthorhombic | mohs 5.5 to 6.0 | 4.133 g/ccm )
Wikimedia:
- CC licensed images of rutile Category:Rutile – unfortunately no transparent specimens there (2021) aside from an artificial single crystal
- CC licensed images of brookit Category:Brookite
- CC licensed images of anatase Category:Anatase