This effect is real, as this Russian paper shows, https://www.sciencedirect.com/science/article/pii/S0038109803003673 .
Natural carbon diamond conducts heat five times better than copper whereas natural silicon conducts heat three times worse. Isotopically pure carbon makes 50% better thermal conductivity, https://en.wikipedia.org/wiki/Isotopically_pure_diamond. Also silicon isotopes are: silicon 28 92.2% silicon 29 4.7% silicon 30 3.1% https://en.wikipedia.org/wiki/Silicon. Mono-isotope silicon has been investigated in order to make possible the exact determination of Avogadro's number, ~6.02x10^26 atoms/mole=protons/kilogram. It can then be grown in a precise diameter sphere. See https://www.nist.gov/si-redefinition/kilogram-silicon- spheres-and-international-avogadro-project . The Kibble balance just recently won out over the Avogadro project because it is more repeatable and accurate. BTW, quartz is silicon oxide, which is a totally different beast than pure silicon. Even if the quartz is mono-isotopic the oxygen would have to be as well. Oxygen is also present in three isotopes: O-16 99.76% O-17 0.04% O-18 0.20% https://en.wikipedia.org/wiki/Oxygen I doubt that crystal improvements are possible with quartz made with atoms that are mono-isotope. Mechanical properties depend upon electron shell attractions and the number of neutrons in the nucleus have little to do with it. Quartz molecules are five times heavier than carbon atoms. Isotopic effects must also be much less. Growing pure quartz crystals is more important that worrying about isotopes. Any impurities disrupt the structure and cause dislocations. This reduces Q by increasing ESR. Quartz has an intrinsic Q of 16x10^6 divided by the frequency in megacycles. I don't know the source of that limitation but I doubt that it is thermal conductivity. Even then this would be a multi million dollar project. What good would slightly better thermal conductivity do if the crystal blank is all at the same temperature to begin with? I cannot find anything on Q effects from single isotope quartz. Even an improvement of 50% in Q is hardly worth raising the price of quartz by 1,000:1 to make it mono-isotope. Money is likely much better spent on ways to grow quartz better and faster. There has been a little work done on levitating crystal blanks by high voltage RF fields so that no loss or instability is present in lead attachments. I have done a lot of calculations on that subject. I talked to Bliley about it some 15 years ago. Less than a Watt was sufficient to levitate a crystal by a few microns in a 100 g vibration environment. Something like 30 pFd of series capacitance would be present on each face of the blank. WB0KVV On Sun, Apr 22, 2018 at 9:22 AM Poul-Henning Kamp <[email protected]> wrote: > > Silicon comes in a number of isotopes but 95% of it is Silicon-28. > > When you make pure mono-crystaline silicon, you get 50-60% better > thermal conductivity if you only use Silicon-28 atoms. > > Yes, you read that right: 50-60% improvement for removing the > remaining 5% other silicon isotopes, and for this and other reasons, > sorting silicon atoms by isotope is now a thing, which amongst other > side effects have made the Advogardo Project possible. > > I can't help wonder if there may be similar interesting effects in > quartz crystals, if they were monoisotopic ? > > Several relevant mechanisms can be imagined, lower internal damping, > higher stiffness etc. etc. > > We know a LOT about quartz and have a very good theory for its > behaviours, but i find no signs anybody has ever touched monoisotopic > Quartz. > > The obvious experiment is not rocket-science, nor does it demand > inordinate resources for amateurs, see for instance from 03:35: > > https://archive.org/details/59554KrystallosCF > > But it is clearly beyond what I have time to persue. > > Do we know anybody in the quartz business who needs a really cool > research project ? > > Poul-Henning > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > [email protected] | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
