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{{wikitodo|There was a significant mixup with '''neo-isotypes''' here. Do some more cleanup & checks if transition succeeded.}}
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{{site specific term}}
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A '''neo-polymorphic compound''' (or neo-isomorphic compound) is an exclusively mechanosynthetically accessible highly stable non equilibrium polymorph of a material with a certain fixed stoichiometry.
A '''neo-polymorphic compound''' (or neo-isomorphic compound) is a highly (meta)stable non equilibrium polymorph <br>
of a material with a certain fixed stoichiometry that is exclusively accessible through [[mechanosynthesis]]. <br>
If just one element is involved the term '''[[neo-allotrope]]''' can be applied too/instead.
 
This includes patterns where specifically ordered states are thermodynamically not more attractive <br>
than disordered (or in other undesired form ordered) states but <br>
where a (sufficiently) high activation energy lies between the ordered and unordered states <br>
making the via conventional means inacessible states highly kinetically metastable. <br>
 
The patterns can be:
* different stacking geometry, specific example: <br>A crossover between Diamond (cubic stacking) and lonsdaleite (hexagonal stacking). <br>(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).
* changes between different crystal structures of the same composition (adn stoichometry) so long nigh seamless covalent transitions are possible
Excluded here:
* changes of atom types and stoichometry falls under [[neo-isotypes]] instead: <br>specific example: A crossover gemstone between Rutile (polymorph of TiO<sub>2</sub>) and stishovite (polymorph of SiO<sub>2</sub>). <br>The pattern making elements are Ti & Si. Oxygen atoms stay at their places.
 
Stacking order 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
* ABBAABBAABBAABBAABB – '''neo-polymorph''' – wanted peculiarly ordered state – not thermodynamically accessible - but accessible via [[mechanosynthesis]]
Note: in the case of SiC ([[moissanite]]) there is the constraint of no two same letters following adjacently. Above examples for simplicity.
 
Also '''[[neo-polymorphs]] and [[neo-isotypes]] can intermix here to [[neo gemstones like compounds]]''' or '''neo-gems''' for short. <br>
All sorts of II-IV semiconductor compounds have fitting structure stacking order variations in {111} directions. <br>
So structural stacking order can be augmented with material type stacking order. <br>
Material stacking order not being constrained to the by {111} directions but by lattice strain. <br>
 
Note: '''Thermodynamic accessibility''' refers to all the crude processes available today (2025) <br>
that only allow to handle matter in statistical quantities: <br<
melting, mixing, cooling, pressurizing, irradiating, ([[cook mix and stir thermodynamic synthesis]]) ... <br>
This explicitly excludes advanced [[mechanosynthesis]].
 
== Examples ==
 
See: [[pseudo phase diagrams]] for more details on this.
 
* [[Dialondeite]] cubic to hexagonal series
* [[Moissanite]] cubic to hexagonal series
* genrally: cubic zincblende structure to hexagonal wurzite structure series (for all applicable compounds respectively, mostly III-V semiconductors)
----
Other patternd back and forth transitions between small chunks of highly compatible crystal structures:
* [[withe sapphire]] to [[deltalumide]] (unclear if transitionable)
* [[silicon nitride]] trigonal alpha to hexagonal beta & (unclear) to cubic gamma
* SiO<sub>2</sub> low pressure modification transitions - see page: [[Quartz]]
* … {{wikitodo|Find more examples to put here}}


== Related ==
== Related ==


* [[pseudo phase diagram]]
* [[Neo-gems]]
* [[diamondoid compound]]
* '''[[Neo-isotypes]]'''
* [[binary diamondoid compound]]
----
* [[Classifications for gemstone like compounds]]
----
* '''[[Pseudo phase diagram]]''' - mapping out neo-polymorphs
* [[Simple crystal structures of especial interest]] - browse there as a starting point
-----
* [[Diamondoid compound]]
* [[Binary diamondoid compound]]
----
* [[Kaehler bracket]]s
----
'''Examples:'''
* [[Dialondeite]]


== External links ==
== External links ==


* Wikipedia: [https://en.wikipedia.org/wiki/Polymorphism_(materials_science) Polymorphism (materials science)]
Wikipedia pages:
* Wikipedia: [https://en.wikipedia.org/wiki/Polymorphs_of_silicon_carbide Polymorphs of silicon carbide]
* [https://en.wikipedia.org/wiki/Polymorphism_(materials_science) Polymorphism (materials science)]
* Wikipedia: [https://en.wikipedia.org/wiki/Isomer isomer], [https://en.wikipedia.org/wiki/Stereoisomerism stereoisomer], [https://en.wikipedia.org/wiki/Conformational_isomerism conformational isomer]
* [https://en.wikipedia.org/wiki/Polymorphs_of_silicon_carbide Polymorphs of silicon carbide]
* Wikipedia: [https://en.wikipedia.org/wiki/Superstructure_(condensed_matter) Superstructure (condensed matter)]
* [https://en.wikipedia.org/wiki/Isomer isomer], [https://en.wikipedia.org/wiki/Stereoisomerism stereoisomer], [https://en.wikipedia.org/wiki/Conformational_isomerism conformational isomer]
* [https://en.wikipedia.org/wiki/Superstructure_(condensed_matter) Superstructure (condensed matter)]
* [https://en.wikipedia.org/wiki/Isomorphism_(crystallography) Isomorphism_(crystallography)]
----
* Isotype: [https://www.mineralienatlas.de/lexikon/index.php/isotyp?lang=de (de)] Translated citation: "Minerals of the same structural type are called isotypes. They crystallize in the same class of crystals and form similar crystal forms. "
* Isotype: [https://de.wikipedia.org/wiki/Isotyp (wikipedia de) Isotyp]
----
* [https://www.mineralienatlas.de/ www.mineralienatlas.de] <br>lists minerals with equal or similar structures for any given mineral <br> so thhis can serve as a possible starting point to find potential neo-polymorphs
 
[[Category:Far term target]]

Latest revision as of 19:10, 29 March 2026

(wiki-TODO: There was a significant mixup with neo-isotypes here. Do some more cleanup & checks if transition succeeded.)

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 (meta)stable non equilibrium polymorph
of a material with a certain fixed stoichiometry that is exclusively accessible through mechanosynthesis.
If just one element is involved the term neo-allotrope can be applied too/instead.

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
making the via conventional means inacessible states highly kinetically metastable.

The patterns can be:

  • different stacking geometry, 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).
  • changes between different crystal structures of the same composition (adn stoichometry) so long nigh seamless covalent transitions are possible

Excluded here:

  • changes of atom types and stoichometry falls under neo-isotypes instead:
    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.

Stacking order 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
  • ABBAABBAABBAABBAABB – neo-polymorph – wanted peculiarly ordered state – not thermodynamically accessible - but accessible via mechanosynthesis

Note: in the case of SiC (moissanite) there is the constraint of no two same letters following adjacently. Above examples for simplicity.

Also neo-polymorphs and neo-isotypes can intermix here to neo gemstones like compounds or neo-gems for short.
All sorts of II-IV semiconductor compounds have fitting structure stacking order variations in {111} directions.
So structural stacking order can be augmented with material type stacking order.
Material stacking order not being constrained to the by {111} directions but by lattice strain.

Note: Thermodynamic accessibility refers to all the crude processes available today (2025)
that only allow to handle matter in statistical quantities: <br< melting, mixing, cooling, pressurizing, irradiating, (cook mix and stir thermodynamic synthesis) ...
This explicitly excludes advanced mechanosynthesis.

Examples

See: pseudo phase diagrams for more details on this.

  • Dialondeite cubic to hexagonal series
  • Moissanite cubic to hexagonal series
  • genrally: cubic zincblende structure to hexagonal wurzite structure series (for all applicable compounds respectively, mostly III-V semiconductors)

Other patternd back and forth transitions between small chunks of highly compatible crystal structures:

  • withe sapphire to deltalumide (unclear if transitionable)
  • silicon nitride trigonal alpha to hexagonal beta & (unclear) to cubic gamma
  • SiO2 low pressure modification transitions - see page: Quartz
  • … (wiki-TODO: Find more examples to put here)

Related

Examples:

External links

Wikipedia pages:

  • Isotype: (de) Translated citation: "Minerals of the same structural type are called isotypes. They crystallize in the same class of crystals and form similar crystal forms. "
  • Isotype: (wikipedia de) Isotyp
  • www.mineralienatlas.de
    lists minerals with equal or similar structures for any given mineral
    so thhis can serve as a possible starting point to find potential neo-polymorphs
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