Talk:Yttrium barium copper oxide

message: The diagram in the "structure" section appears to be wrong.  It disagrees with the description, with the 3-D diagram at the top of the page, and with the article on perovskite structure.
In particular: the copper atoms and the oxygen atoms should be switched.  If Barium is the center of a cube, then copper should be at the vertices of the cube, and oxygen at the middle of each edge.
Note: I'm saying the yellow dots need to be swapped with the red dots.  Just changing the legend would be a bad idea, since we should stick with the convention of using small red dots for oxygen. --Tim314 16:44, 18 September 2006 (UTC)
replies: text: Good catch. I wonder how many people that's confused. I've nominated the image for deletion, because I don't see a good way to fix it without starting over from scratch. —Keenan Pepper 19:55, 20 September 2006 (UTC)
replies: text:  Was image changed ? In June 2008 both seem to match the description at perovskite. Rod57 (talk) 19:47, 11 June 2008 (UTC)
thread_title: structure diagrams

message: Is not Cubic.  Should be ortho Rhombic the lattice constants a does not = b does not = c
* in YBCO a is very similar to b at 0.382 and 0.389 nm respectively, so for "high school science" one can assume a=b. By the way, c is 1.168 nm. 
LMB (talk) 09:46, 6 November 2008 (UTC)
thread_title:  Coordination Geometry 

message: R Ba2 Cu3 O(7-delta) where R is a rare earth element Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
I am surprised this page quotes YBa2Cu3O7 as it as a defect ceramic material, not a molecular compound - in all cases.  —Preceding unsigned comment added by 125.7.52.129 (talk) 04:19, 29 September 2008 (UTC)
thread_title:  Related Compounds 

message: YBCO is a type 2 superconductor and only expels magnetic field up to a certain strength called Hc1. after this value is reached magnetic field penetrates the superconuctor in the form of vortices.  Anon - sometime.
This section of the article applies to all superconductors and should be moved there is not already there. Rod57 (talk) 23:45, 4 September 2008 (UTC)
thread_title:  Magnetic Levitation 

message: The levitation of a magnet above YBCO has nothing to do with the Meissner-effect. The Meissner-effect only occurs in Type I superconductors as the magnetic field is expelled from the superconductor. In order for a magnet to levitate, it is required that magnetic flux lines may "pin" into the material (pinning effect). The magnet would just fall off otherwise. Thus the magnetic levitation is an effect of type II superconductors and has nothing to do with the Meissner effect. 
Fat kanickel 14:40, 12 December 2006 (UTC)
thread_title:  levitation 

message: What does T represent in this sentence: 120 T for B perpendicular and 250 T for... Mrshaba (talk) 21:40, 3 Jul 2008 (UTC)
replies: text: Disregard question. I linked T to the unit page. Mrshaba (talk) 21:49, 3 July 2008 (UTC)
thread_title:  More explanation please 

message: Regarding the sentence 
 Its upper critical field is 120 T for B perpendicular and 250 T for B parallel to the CuO2 planes.
...I'd like to comment that Hc2 is unimportant in Type II superconductors, because before Hc2 can destroy the superconducting phenomenon, there's the much smaller (ca. 10..20T) Hirr, or 'irreversibility field', which causes the magnetization loop to reverse. The area between Hirr and Hc2 has vortices, but is completely useless from the industrial use point of view. LMB (talk) 10:15, 6 November 2008 (UTC)
thread_title:  "upper critical field" is unimportant 

message: I've made a few images of the unit cell and of the coordination geometry of each metal atom in YBa2Cu3O7-\delta. If these are useful, I can provide similar polyhedra for the five different oxygen environments.
           	                     	                 	                       	
cubic {YO8}	cuboctahedral {BaO12}	octahedral {CuO6}	square pyramidal {CuO5}	YBa2Cu3O7-\delta unit cell
Ben (talk) 20:13, 20 January 2009 (UTC)
replies: text: Fair point, I think this must be crystallographic disorder in the literature structure I used. Thanks for spotting these errors. I've updated the article, only 12 years late. --Ben (talk) 16:43, 6 April 2021 (UTC)
thread_title:  Coordination polyhedra 

message: I deleted the claim that "Amperium superconductor wire exhibits conductivity approximately 200 times that of copper wire of similar dimensions," for two reasons:
*It makes no sense, as the conductivity of a superconductor is infinite.
*The cited source ( http://www.nature.com/news/2010/101008/full/news.2010.527.html ) makes no mention of either Amperium or conductivity.
GPS Pilot (talk) 10:31, 4 February 2016 (UTC)
thread_title:  Not 200 times that of copper 

message: The figure/movie in the "proposed applications" section showing the levitating vessels containing YBCO uses the caption "Like all superconductors, YBCO displays the Meissner effect."...  As true as this may be, the levitating YBCO (and almost all similar levitation demonstrations, except for magnets floating above lead or niobium bowls) is not an example of the Meissner effect, but rather of flux pinning.  While closely related phenomena, there is an important distinction between expelling all flux lines from the bulk (Meissner) and allowing flux lines to penetrate but force them to remain fixed (pinning).  This isn't just nitpicking -- the pinning keeps the samples levitating stably at constant height/transverse position with respect to the track (and from falling off) while in the Meissner state the sample would just be pushed away from the track. (You can't do this sort of thing with lead.)
So I'm going ahead and changing it; please change my new version if you don't like it (but hopefully not to the Meissner explanation). Lambda(T) (talk) 21:49, 12 April 2017 (UTC)
thread_title:  Meissner effect figure misleading