If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
Hi all.
I have come up with a possible method of increasing the useable fraction by utilising heat assisted electromigration to "force" the lattice into the desired formula combined with a novel way of laying out the initial compounds alternating with the barium and calcium oxides. In theory it could work, in much the same way as molten glass conducts electricity.
I hope to have something working shortly, this all depends on how long it takes me to build the sintering jig using fire bricks and tungsten welding rod as the electrodes, and hydrogen peroxide + MnO2 as the oxygen source.
As for testing it, a relatively simple approach is to stack three peltier junctions then water cool the "base" to reduce the thermal gradient allowing the stack to reach -40 Celsius in principle. Obviously it will not superconduct at this temperature but I can observe the drop in resistance
(maybe there is a use for one of those car aircon pumps..)
EDIT:- I found a reference to using induction heating in order to alter the microstructure of a superconducting disc to change the formula very slightly, in a similar way that it is used to anneal metal alloys. if this works with the high temp. materials then I might be able to synthesize higher useable fractions without messing around with the oxygen content.
"After that, the disk was put back in the furnace at 600C, and the upper surface was quickly heated to 1200C using a planar high frequency inductor as shown in Figure 1. During this last heating, the gap between the disk and the inductor was chosen precisely so that heating would occur only in the top 2 mm-thick layer of the disk, although the material's high heat conductivity caused some heating below this region"
For those looking into making these materials, be aware that even microscopic quantities of some contaminants such as iron and nickel can quench superconductivity entirely even at LN2 temperatures. I'd avoid low purity "ceramics grade" chemicals even though they are cheaper, unless you have a way to test them for contamination and purify them.
Depending on exactly what the contaminant is it may be possible to chemically separate them, iron oxide being somewhat insoluble could be extracted in this way and crystallising barium carbonate then regrinding to a uniform particle size would get rid of some (thanks for the tip Weston!)
as for induction heating,
EDIT:- I have emailed NASA re. a similar idea, am waiting for a response. Making HTSCs cheaper would be one way to get my name in the history books, if low grade materials could then be used for direct radiation shielding by tweaking the formula..
-A
EDIT: Due to IP conflict I have removed references to the site.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Homemade superconductors?
