Rutile structure
From apm
Crystal structure: tetragonal
List of compounds with rutile structure
Various compounds that all share the rutile structure and thus
may be amenable to patterned substitution by atoms of compatible elements thereby
spanning up new areas of pseudo phase diagrams
(here ordered by elemental abundance in earths crust):
- Stishovite SiO2 - not quartz - (Mohs 9.5 | silicon is the most common element on earth excluding oxygen) - 4.35g/ccm - heat resistance may be limited due to metastability
- Rutile TiO2 (Mohs 6-6.5 | titanium is very abundant)
- Pyrolusite MnO2 (Mohs 6-6.5 | Mn is not too rare but todays mining is environmentally destructive)
- Niobium dioxide = Niob(IV)-oxid NbO2
- Cassierite SnO2 (Mohs 6-7)
- Plattnerite β-PbO2 (Mohs 5.5 unusually hard for a lead compound | useful high density of ~9 g/cm3)
- Note that lead Pb tin Sn and niobium Nb are similar in their not too high abundance.
- Argutite GeO2 (Mohs 6-7 | germanium is pretty rare)
- Tripuhyite FeSbO4 (Mohs 6-7 | Antimony Sb is a little more rare than germanium Ge.)
The much more common phosphorus analog FePO4 forms a soft hydroxide Strengite with different crystal structure (phosphate).
But maybe it can be mechanosynthesized in rutile structure? - Paratellurit (de) TeO2 (soft compound and tellurium is extremely rare)
- MgF2 Magnesium fluoride mineral sellaite – Mohs 5.0 to 5.5 – 3.15g/ccm – very slightly soluble in water (0.13g/liter)
A special focus on Stishovite?
Stishovite may be of especial interest because
of the abundance of silicon and because
of its better qualities than quartz like:
- way higher hardness
- the rutile structure being simpler and higer symmetry than the quartz structure
- denser structure with less voids
It may not be very heat resistant though, since it is only metastable at low pressures. To determine.
Element substitutions with the elements from the compounds listed above may improve on heat stability while possibly degrading other properties.
Maybe a tradeoff? Maybe a win-win?
