Revision as of 17:29, 24 May 2021

In the future we will build with gemstones.

moissanite aka silicon carbide (SiC) - a typical gemstone-like (diamondoid) material - without impurities it would be transparent like diamond - the silicon makes this material fireproof in bulk blocks but also inhibits the possibility to intentionally burn it up completely to gasses since - it partly turns into glassy slack or fly ash instead

Definition – What is a gemstone like compound?

Gemstone like materials encompass all materials that ...

• ... have their atoms not moving around on their surfaces at room temperature but have them stay where they are for decades to eons. (they do not diffuse)
• ... are stiff enough to keep their shape under thermal movement at room temperature (this excludes all of today's plastic polymers)
• ... have dense three dimensional networks of covalent bonds like gemstones - (short bond loops prevent rotations around single bonds)

Use – What are gemstone like compound good for?

Gemstone like materials ...

• ... serve as the fundamental basis for an unimaginably wide variety of possible gemstone based metamaterials.
• ... include many neo-polymorphic compounds that currently can't be produced (via thermodynamic means).

Introduction

Why the focus on gemstone like compounds

Gemstone-like (or more narrow diamondoid) compounds are the material of choice for:

• crystolecule based nanoscale machine elements
• crystolecule based nanoscale structural elements

Crystolecule and their assemblies (microcomponents) and
all forms and fashions of assemblies of both of them into gemstone based metamaterials are
what is the essence of the products of advanced future gem-gum technology.)

Lower error rates in assembly & Products not decaying away just from room temperature heat

The main reason for why gemstone like compounds are the material of choice here is that at room temperature their atoms do not jitter and wobble around too strongly or even diffuse away. This is important

• in the final product that should not start quickly decaying the moment it finished assembly
• in the assembly process where crystolecules pout of gemstome like compounds are built up almost atom by atom via robotic manipulation.

For the assembly process more specifically one needs to choose a gemstone like compound that is sufficiently stiff such that a manipulator made out of this compound can keep the amplitudes of the thermal vibrations that occur at the manipulators tip sufficiently smaller than the lattice spacing of the work-piece that is made out of the same (or an other) gemstone like compound. This way placement errors can be suppressed. That is: errors can be made very very rare, like bit errors in digital computing. (Related: Lattice scaled stiffness)

Low error rates are also important in light of that in final production devices the assembly process is for the most part a a blind process that can't see or correct its own errors.

Rigid bodies are easier to work with than floppy jiggly folding fluff

Products out of gemstone like (diamondoid) materials can be made so that they only have one to a few tightly controlled degrees of freedom (axles rails). This is unlike soft nanoscale machinery like in biology wher pushing in on one side all sort of predictable to massively unpredictable things can and often will happen.

With only a few clearly defined independent degrees of freedoms for motions one can more easily test one action at a time (Related: Microcomponent maintenance units). This is a fundamental engineering principle that allows for faster progress. In contrast a systems design that poses the necessity for scientific entangling of convoluted relationships is usually considered bad. Natural nanosystems (e.g. like e.g. the case in soft natural proteins with barely predictable folding and behavior as present in living cells) are like this. Likely because of random incremental evolution in small steps without any far look-ahead that only higher thought would enable. In this regard one obviously shouldn't copy from nature.

Stability against water and other chemicals

Gemstone like compounds that are intended to be used on the surface of products have additional requirements on chemical stability. First and foremost in most cases one wouldn't want them to be water soluble. But resilience against stronger acids bases and oxidizers may be desired too. This drastically restricts the range of usable compounds when it comes to the surfaces of products.

The majority of the material a product is made out of lives well isolated on the inside of the bulk product. Thus for most of the products total volume (all the inner volume) the wider less chemically stable range of material is open for usage.

Adding protective hulls and compartmentalization as a workaround

It's a bit like the protective skin of fruits. The outer skin must be made out of a much more chemically stable material than the delicate inside and once the inside is exposed it may quickly decay. (Related: Passivation,Surface passivation, Biological abnalogies) Unlike in fruits though gemstone based metamaterial can be made designed to be micro-compartmentalized. That is: Each and every microcomponent may have a hull out of a few chemically highly stable gemstone like compounds and an interior with a greater range of much less chemically stable gemstone like compounds. A good design could make breaking up some microcomponents by macroscopic impact nigh impossible. Well, excluding hyper-velocity impacts here, like those one would expect when space debris impacts into spacecraft hull.

How material solubility and environmental friendlyness relate

Extensive usage of water dissolvable materials out of non toxic elements may even help biodegradability. Products should though be designed in a way that non-water-dissolvable nanoscale parts can't come loose individually (or sparsely and fragilely connected). A worst case scenario would be that due to bad designs huge quantities of water (and acid) undissolvable nanoscale parts come loose spill into the environment accumulate there and eventually cause lots of harm to animal and human life.

Difference to normal gemstones and relation to metamaterials

By mechanosynthesizing gemstone like materials one can go far beyond the known polymorphs (or allotropes).

• Poly morphs are various crystal structures of all the compounds with one and the same chemical formula. – Example: rutile and anatase are both TiO₂)
• Allotropes are are the polymorphs of compounds made from one single element compounds. – Example: diamond and lonsdaleite are both pure carbon (C)

One can go far beyond all the phases that are reachable by conventional thermodynamic means of material production that all lack atomically precise control. The newly accessible phases of the same old mundane chemical formulas include thermodynamically unstable but strongly metastable ones. A peculiarly interesting case is stishovite. Here a material with the well known formula SiO₂ (which usually points to our good old friend quartz) suddenly makes an enormously hard and dense material.

On the blurryness of a delineation between base material and metamaterial

With bigger neopolymorphic patterns the maerials become

• less of a high level base materials and
• more of a low level metamaterials.

That is: It may not be possible to draw an entirely sharp line between low level gemstone like compounds and high level gemstone based metamaterials.

Properties of low level metamaterials:

• inacessible by means of conventional thermodynamic means of production only accesible via mechanosynthesis
• they are quite complicated neo-polymorphs
• they can still be considered to be a base material for mechanical metamaterials out somehow interlocking crystolecules
• their complex structure is giving them properties that are quite different to what could be considered their base material (thus metamaterials)
• development of them is not as easy and straightforward (relatively seen) as the development of higher level structural metamaterials

Giving some more details:
Low level metamaterials include very stable patterns that are highly ordered. Those patterns may include vacancies and may have periods of repetition of arbitrary length. Their structural alterations are small enough to influence properties that originate at such a low size scale. Influenced properties include chemical, electrical, magnetic, and other properties.
(Side-note: This is especially relevant for the non mechanical technology path).

A simple example of a low level metamaterial is when donation atoms are embedded in a checkerboard or other exactly periodic pattern.
The distinction between low level metamaterials and high level metamaterials may be difficult in some cases.

• Conventionally doped semiconductors with their statistically embedded doping atoms are not called metamaterials.
• Mechanosynthesized materials with highly complex patterns of atoms inside may deserve to be called low level metamaterials.

Things that can be influenced on this very low level involve:

• The shape of the Fermi energy level in the Brilloin zone – which is the crystal unit cell in Fourier transformed space – in reciprocal space – ("periodicity space")
• Band-gaps, Electron density of states
• dispersion relations for photons
• dispersion relations for phonons – relating to thermal conductivity properties
• transport properties for all sorts of all sorts of quasi particles
• mechanical properties – (here of most interest)

This is all very useful but also very difficult. Often one finds a solution solving only one particular problem.
One point of gemstone like compounds as base materials for gemstone based metamaterials is that one only pick and develops a few with complementary properties. And then one satisfyingly "fake" all else with combinations of these few which takes orders of magnitude less effort and even makes possible things that without the "faking" wouldn't even possible at all.

The set of sufficiently metastable low level metamaterials is significantly bigger than
the set of designed materials that is accessible today (2014..2017..2021) through cooking it together by macroscopic means.
This set of designed materials favors random mixing because they require very restrictive good thermodynamic accessibility.

Carbons versatility

By the time of last review (2017) carbon is the only building material for which extensive studies about tooltip chemistry have been undertaken.

Carbon (especially in the form of diamond) has been chosen because it constitutes a particularly difficult far term test case for exploratory engineering. It has not been chosen as an easy to reach near term objective to target directly.

By structuring just carbon alone, with just a bit hydrogen as passivation agent (no further elements), to mechanical metamaterials many material properties will be achievable.

Beyond carbon from acetylene and methane many further studies are needed most importantly:

• machanosynthetic splitting of water for scavenging usable oxygen
• direct splitting of oxygen
• splitting of nitrogen - artificial and different to current natural or industrial methods of nitrogen fixation.
• splitting of carbon dioxide
• fluorine and the nonmetal elements of the third period

Carbon nanotubes can replace the scarce element copper for electrical cables.

gemstone-like vs diamondoid

Instead of "gemstone like compound" the term "diamondoid compound" can be used.

This may have a more restrictive meaning limiting focus towards compounds that are easy to passivate and thus more suitable for machine elements with sliding interfaces. This primarty entails the exclusion of salts (like e.g. Periclase MgO) and secondary the exclusion of big class of metal oxides, sulfides, nitrides and related compounds (e.g. Sapphire, Pyrite, titanium nitride (Osbornite), ...)

Related: The too strong exclusive focus on diamond only. See: "Pathway controversy".

Gemstone like compounds

Please keep in mind that all compounds we know of today are only those few we can create by mixing and cooking various elements or preproduced compounds together. With mechanosynthesis many more will be accessible. Although they're not in a thermodynamic minimum they'll be very stable at room temperature. A recent example is the theoretical prediction of the stability of graphitic pentagonal carbon sheets with the so called cairo pattern. The "few" compounds we can create by mixing and cooking them together are all the minerals that are documented today. These will be surveyed here. Many more meta-stable compounds will become mechanosynthesizable though for most applications the allotropes of carbon used in their high level metamaterial configurations alone will suffice.

Taking the rock forming mineral quartz one finds several natural polymorphs. The "quartz group".
Beyond those natural polymorphs Neo-polymorphs of SiO₂ will be accessible via mechanosynthesis
which are (albeit their deviation from thermodynamic equilibrium) very stable but not accessible today.

See main article: Polymorphs of silicon dioxide and pseudo phase diagrams

Lists of potential structural compounds

For especially interesting ones check out: "Charts for gemstone-like compounds"

early materials

• gem-like biominerals ... compounds that are synthesizable under solution are of interest for technology level II to bridge the gap between technology level I and III.

pure elements

• C carbon sp3 network allotropes: diamond, lonsdaleite; sp² allotropes: fullerenes, graphitic networks
• Si silicon (also cubic or hexagonal)
• B ~four allotropes of elementar boron (may be difficult to use)
• P & S allotropes of phosphorus and sulfur (may be difficult to use because of what follows below)

some classifications: (a high dimensional overlapping space of possibilities)

• Base materials with high potential
• Simple crystal structures of especial interest

• Binary gem-like compounds
• Gem-like compounds that contain (partially abundant) s-block metals
• Ternary and higher gem-like compounds (including cubic garnets)
• refractory materials

• Gem-like compounds containing elements of the 13th group
• high pressure modifications
• electrically conductive gem-like compounds

Issues with more complex compounds

Metamaterials made from the basic gemstone-like materials are able to emulate a lot of physical properties.
Further binary ternary or higher gemstone-like materials can complicate engineering design due to:

• low symmetry in their crystal structure - See: Isotropy of materials
• porousness due to bridge bonding like present in all salts of oxoacids X-O-X (X can be e.g. Si,Al,P,...) and some other compounds
• complex or polar surface structure which may be difficult to passivate
• lack of tensile strength
• ...

thus they may predominantly find use for special applications like as:

• slowly water dissolvable materials for better biodegradability
• laser gain materials
• infill materials
• materials with special electrical magnetical or other exotic non high level emulatable properties
• ...

In the following classifications section you'll find a lot of links to wikipedia articles about gem-grade minerals with very beautiful pictures. Please note that the colors you see are in most of the cases due to small impurities and not inherent to the minerals themselves. Most (electrically non conductive) minerals will be completely transparent when built defect and impurity free. An extreme example is silicon carbide known as a black solid but in single crystalline form it's called mossianite and completely transparent. Color should be intentionally addable by mechanosynthetic sparse checkerboard dotation.

compounds which contain relatively scarce elements

Those may be useful in the lower technology levels or special tooltip chemistry where only very small amounts are needed (e.g. germaium containing tips).

• molybdenium oxide structures
• germanium compounds
• ... many more

Sources for elements

Carbon is planned to be drawn from [ethyne] more commonly known as the welding gas acetylene. It has the advantage of a triple bond that when partly split up provides four unpassivated bonds and it's carrying around a minimal amount of hydrogen. Since DMEs are compact and crystal like they have a lot less surface than the source molecules and thus require a lot less hydrogen passivation. Ethyne cant be delivered in highly compressed gaseous form since it explosively decomposes. It is hardly soluble in water but well soluble in acetone ethanol or dimethylformamide. Ethyne can be manufactured by the partial combustion of methane and thus potentially be gained from renewable resources.

If one looks at the most common or most easily accessible elements and their simplest compounds one finds a list of potential structural building materials:
Link to a graphic of the most common elements in the earths crust from Wikimedia Commons.

Most easily accessible are nitrogen oxygen and argon since they can directly be drawn from the atmosphere.
To investigate:

• Means for filtering/capturing N₂ and O₂ each selectively from the atmosphere.
• Mechanosynthetic tooltips and manipulations to gain reactive moieties out captured N₂ and O₂.

drawn from the atmosphere

Oxygen and nitrogen rich compounds like SiO₂ and Si₃N₄ are interesting because more than half of this material can be drawn directly from the atmosphere. When atmospheric carbon dioxide is used carbon allotropes and β-C₃N₄ can be drawn 100% from the air.

back to the atmosphere

When burning diamondoid materials (hopefully in a smart way - thus only in traces - see recycling) it strongly depends on the type of chosen material whether they convert to gasses or just reform to a glassy slag. In the latter case it will be more difficult to recover the elements in pure form. The rough rule is: When heated under oxygen mainly carbon based materials burn up almost completely while silicon or metal oxide based materials just melt to a slag. Everything in between could be possible. Certain combinations of elements can become dangerous when burned together as we know from the PVC dioxine problem.

Chlorine

Chlorine could be drawn from common salt leaving behind sodium. To get this residual into a nonreactive environmentally acceptable form that could be used as structural material rather than just constituting waste one could chose from sodium minerals. To prefer are compounds with no crystal water and simple formulas with only elements of high importance for APM (that is which we are likely to gain control of soon after reaching technology level III) like e.g. jadeite and further ones to find.

The 13th group

Elements of the 13th group (the boron group) are special in that they can form electron deficiency bonds.

If elements of this group come into play (are used in DMEs) the view of atoms as construction blocks with a fixed number of connection points breaks down. E.g. when boron comes in contact with nitrogen the lone pair of nitrogen plucks into the electron deficient hull of boron making the two atoms more behave like two four valenced carbon atoms (with a little polar/ionic character). Prime example: ammonia borane. This is not yet handeled correctly by the software Nanoengineer-1 so it is advised to refrain from using 13th group elements for DME design for now.

In high quantities both solvated aluminum and boron compounds are alien to human and natural biology. Intake can lead to bad or unknown effects. Thus one might refrain from using strongly water soluble compounds of 13th group elements. Some information can be found here: boron and water (de); aluminum and water (de)

In tooltip chemistry boron and aluminum may be useful as tool-tips for the handling of atoms with almost full electron shells like oxygen fluorine sulfur and chlorine effectively increasing their normally low bond number. (To verify!)

Possible alternatives names

• gemstone like, gem-like, gemstoneoid, gemoid – (diamondoid is more specific and usually does not include gemstones like sapphire or quartz)
• compound, material, substance

Related

• Base materials with high potential
• Simple crystal structures of especial interest
• Semi diamondoid structures
• Find diamondoid compounds by the elements they contain.
• Mechanosynthesis
• Surface passivation
• Surface reconstruction
• The defining traits of gem-gum-tec

External links

• Wikipedia has its own page about diamondoid materials. See here: [1]
• Wikipedia: Allotrope

Table of Contents

Todo

• add some beautiful images of minerals in their gem grade form
• pseudo phase diagrams
• add nanosystems definition of "diamondoid"