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.
Banned on April 7, 2007 Registered Member #277
Joined: Fri Mar 03 2006, 10:15AM
Location: Florida
Posts: 157
"Gadolinium's temperature is observed to increase when it enters certain magnetic fields". What I'd like to know is does the temperature of Gadolinium remain increased as long as the magnetic field remains constant... or is the temperature increase of Gadolinium just momentary... due to a 'magnetic moment' and eventually returns to it's starting temperature. Another way to phrase my question is.. when Gadolinium is placed in a strong magnetic field for 60 mins, will the temperature increase of the Gadolinium be for 60 mins? or will the temperature increase be only a short moment. CM
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
I am not sure about this (haven't done any real chem work for a in months) but I believe that the process works by: 1. the metal when not in a magnetic field has a thermal capacity of some value X joules/moles*K 2. putting it in a magnetic field disrupts the magnetic dipoles, which increases the crystals entropy, and the heat capacity (some value Y). So now it has a heat capacity of X-Y joules/moles*K, but the energy in the sample remains constant (assuming it is well insulated), so the temperature must go up. 4. removing the field realigns the dipoles, increasing the heat capacity, so the temp drops.
So, placing it in a field for 60 minutes would cause the temp to stay high for all 60 minutes, assuming it is well insulated.
But don't get too excited, we are talking temp changes on the order if 1C/tesla...
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
For a give degree of insulation the cooling will be that same no matter how the Gd was heated. If you warmed it up with a lit match or jut by holding it in your hand it would cool down afterwards, In fact that whole point of using Gd as a cooling agent depends on a 3 stage process. You put the stuff in a magnetic field and it warms up a bit. You leave it and it cools ack down to the temperature of the surroundings then you switch off the magnetic field and the Gd cools down to colder than it started.
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.
Gadolinium's temperature
