Rutile
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.
Other polymorphs of (TiO2)
Another polymorph of (TiO2) is 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.
A third polymorph of (TiO2) is 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 may make it a bit less interesting as a potential base material.
Misc
- Titanium is supposedly especially abundant on the moon so future gem-gum products on the moon may feature a lot of rutile for structural parts.
- 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)
- the germanium dioxide mineral argutite (wikipedia) also shares the rutile structure – (germanium is one of the more rare elements though)
- ...
External links
- 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 )