Neo-polymorph

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This article defines a novel term (that is hopefully sensibly chosen). The term is introduced to make a concept more concrete and understand its interrelationship with other topics related to atomically precise manufacturing. For details go to the page: Neologism.

A neo-polymorphic compound (or neo-isomorphic compound) is a highly stable non equilibrium polymorph of a material with a certain fixed stoichiometry that is exclusively accessible through mechanosynthesis.

This includes patterns where specifically ordered states are thermodynamically not more attractive than disordered (or in other undesired form ordered) states but where a (sufficiently) high activation energy lies between the ordered and unordered states.

The patterns can be:

  • different atom types (elements) ... specific example: A crossover gemstone between Rutile (polymorph of TiO2) and stishovite (polymorph of SiO2). The pattern making elements are Ti & Si. Oxygen atoms stay at their places.
  • different stacking geometry or ... specific example: A crossover between Diamond (cubic stacking) and lonsdaleite (hexagonal stacking). (When pointing up a tetrapod of carbon bonds there are two ways one can orient the up facing three bonds in a six direction hexagon).
  • ...

Patterns:

  • ABABBABBBBAABABAABAA – unwanted unordered state – may be the only one that is thermodynamically accessible
  • ABABABABABABABABABAB – unwanted ordered state – may be the only one that is thermodynamically accessible
  • AABBAABBAABBAABBAABB – neo-polymorph – wanted peculiarly ordered state – not thermodynamically accessible - but accessible via mechanosynthesis

Of course arbitrary many elements/layertypes/... are allowed. A,B,C,D,...

Note: Thermodynamic accessibility refers to all the crude processes available today (2017) that only allow to handle matter in statistical quantities: melting, mixing, cooling, pressurizing, irradiating, ... This explicitly excludes advanced mechanosynthesis.

Examples

The rutile stishovite neopolymorphic transition:
The common mineral rutile and the rare mineral stishovite (made out of the two most common elements in earth crust) share the same crystal structure. The rutile structure. Albeit rutile not drawing silicon into its structure naturally (meaning it's thermodynamically unfavourable) (as can be seen with rutile occuring embedded in quartz https://commons.wikimedia.org/wiki/File:Rutile@quartz.jpg) a forced substitution (at least to some degree) may very well be possible via mechanosyntheic means and the resulting product base material may very well be highly (meta) stable at room temperature.

Related

External links

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