One should try doping in any case. If you send me doped powder or pressed pellets we can check whether the sample is superconductiong.

My address is:

Institut Laue-Langevin

6 rue Joules Horowitz

38042 Grenoble cedex 9

France

If it is a Swedenborgite structure with CuO4 tetradra then I expect it to be a frustrated quantum spin system rather than a superconductor. But everybody knows that we know nothing about superconductivity and we can still have surprises. No theory of superconductivity (including BCS with its phonon pairing mechanism) seems to be right anyway. So we should go ahead.

The Co based Swedenborgites are geometrically frustrated antiferromagnets and are p-type conductors that can be hole-doped. Each unit cell should contain four corner-sharing CuO4 tetrahedrons. Three of the tetrahedrons will lie in the same plane to form kagome layers while the fourth tetrahedron forms a triangular lattice. If doped with excess oxygen or hole-doped, the material should become conductive along the kagome layers(forming a two-dimensional electron gas). I am doping the material by replacing half of the Y atoms with Ca, which is the route taken in the Co based Swedenborgite Y0.5Ca0.5BaCo3FeO7. Give me a few days before I mail sample. It will be in a pwder form. Thanks for your interest and feedback. It is greatly appreciated!

It is good that it is p type conductor in the normal state. Then it is already a good candidate for superconductivity.

Have you determined the crystal structure already? If so have you done by powder or single crystal XRD? If you send me the sample I shall also to neutron powder diffraction to check the structure and get better O positions. XRD is not great for O positions in the presence of heavy atoms. Where are your stationed?

Can you make us a target of the size of one inch dia. by an eighth of an inch thick? We would be happy to make an epitaxial film of this material from your target using PLD whereby we can do a number of studies much more easily. Then once you dope the material we can carry on the film work further. We are already doing a similar thing in YBCO where the Ba and Y are replaced by La to form an n-type material but still keeping the structure of the original 123.

You can contact me or my colleague Dr. Ariando. Here is my address:

Prof. T. Venkatesan, Director, NUSNNI-NanoCore, National University of Singapore T-Building, 5A Engineering Drive 1, Singapore 117411. [email protected]

I also can test your sample using both magnetic and electrical measurements, everything is possible if it is new try, why not, still there is no general theory for superconductivity, good luck

sincerely yours...

I'm very interested in the NDE QC of such epitaxial films using real time non-destructive 2D XRD microscopy. I have some very interesting micrographs from work I'd done at BNL with the Condensed Matter Group lead by Dr. Ivan Bozovic. The sample we examined was a 50nm thick MBE Epi of LaSrCuO4 on a LaSrAlO4 substrate 10x10mm. If any of you have epi's of these types of materials, please feel free to contact me for collaborative efforts.

[email protected]

BTW come join us and learn: Friday August 30th, 2013 10AM EST! TAKE ADVANTAGE! "The 3rd Dimension & Beyond in XRD 2013" by Weiguang Guan of McMaster University! http://www.chemistry.mcmaster.ca/facilities/xray/221-max3d

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Since I have limited resources, I am unable to make multiple samples. So, I wanted everyone to know that you can easily make your own sample using the same method that is used to make the 1-2-3 superconductor. The parent compound YLaCu4O7 and the doped version 0.5Y0.5CaLaCu4O7 can be fabricated using a simple solid-state reaction. The materials are sintered at 950 to 1000C for 24 hours. The kiln is then turned off and the material is quenched to room-temperature after the kiln reaches 500C. The resulting material will be a uniform, black powder. Hope this helps anyone that wants to fabricate sample for themselves!

The Swedenborgite structures are known for oxygen adsorption. So, the materials will have more than 7 oxygen atoms if they are cooled slowly. Otherwise, if you quench the materials they will contain 7 oxygen.

I am an independent researcher that fabricates superconductors from my home-based lab. I have been fabricating samples since attending Florida State University(FSU). I got my first lab-grade chemicals from Dr. Louis Testardi(former Director of the Superconductor Program at FSU). I work a full-time job that isn't in the field of superconductivity, but allows me to afford the chemicals and tools to do my research. Over the years, I have had samples tested by Dr. Paul Chu at the Texas Center for Superconductivity and Dr. Larbalestier at the National Magnetic Lab at Florida State University(FSU). I just want to make a contribution to the field. I have been interested in the field for 26 years!

If a compond in its normal state is a semiconductor or metalic conductor, it is expected to meet one of the two possibilities when its T is lowered towards 0. (A) In its most likely possibility it becomes superconductor, if not (B) it is expected to become insulator. It would not retain its normal conducting state at T=0. At what T, a normal or semiconducting state becomes superconducting depends on $d^{-3}$ where $d$ is the diameter of the channel through which the electrical chage carriers are free to move in the normal state (there are other factors too).

I am stating this on the basis of my less known theory which not only concludes an universal reason for the superconductivity of widely different superconductors, but very accuraly renders the $T_c$ of superfluidity of liquid He-3. The same framework also renders a most accurate theory of superfluidity of liquid He-4, which has also not been available till this development. If people come forward to dicuss the merits and demerits of my work I am ready to diiscuss it opnely. Annonymous referees have not done justice to my efforts, although, their action has harmed the development of the physics of superconductors and superfluids more than my academic interests. Possibly this has been due to the fact that my down to earth theories of two phenomena largely contradict the conventional theories.

In addition my papers also establish that BCS theory and similar theories of superconductivity can never provide complete, clear and experimentally consistent microscopic understanding of superconductivity and its dependence on class of materials or individual materials. The basic premises of these theories have intrinsic problems with realities of the low T states of the physical systems.

I am simply waiting to see how long the people working in the field would keep ignoring my efforts.

Please see the following papers for superconductivity :

http://www.scribd.com/doc/110681115/First-Quantization-Theory-of-Superconductivity

http://www.scribd.com/doc/110441679/Intrinsic-Problems-Superfluid-Theories

and following papers for superfluidity of interacting bosons.

http://www.scribd.com/doc/110404594/Theory-Superfluidity-Helium-4

OR

http://article.sapub.org/pdf/10.5923.j.ajcmp.20120202.02.pdf

(my paper in Amer. J Cond Mat Phys.) 2, 32-52(2012)

http://article.sapub.org/pdf/10.5923.j.ijtmp.20120205.02.pdf

published in International J of theor. and Math. Physics .

If anybody finds any difficulty or inaccuracy with my work please let me know I would help you understand its accuracy or I would withdraw my work. BUT please let us discuss in the interest of the development of the science of superconductivity and quantum fluidity at large.

.

Several other supporting papers are avaiable on arXiv.

The best is to try. I can suggest people to do that, if needed

Antonio, I suggest you to go at the university (FSU) and using a four probe system, measure the resistance of sample at LN2, then let us know which is the ratio R(77)/R(300).

I no longer have anyone at FSU that is interested in testing a sample from an unknown person. It is quite difficult getting any established scientist to listen to someone that isnt an expert in the field. I understand their reluctance. I just keep trying until I get someone to listen. I will let all of you know once I get some results.

I'm an inventor/scientist at heart. It says a lot about Researchgate members to give positive feedback and encouragement to an unknown. Thank you!

Antonio:

How soon can you send me a few g of undoped and doped samples? I wish to characterize them with neutron diffraction and check at the same time whether the doped sample shows zero resistance and Meissner effect. This can be done very quickly as soon as the samples are there.

Yatendra: Your response is a bit out of the way. Surely we need a theory that can explain different types of superconductors and also superfludity in 3 and 4He. But here we are concerned wthether the Swedenborgite structure with CuO4 tetradra when doped can produce superconductivity. We are concerned with the hard experimental facts and at the moment we do not need any theory. Theory of superconductivity so far has not helped us experimentalist to find new superconductors so far.

But what you say is very true. There are gatekeepers (Hirsch coined) of BCS and other theories who ignores anything that follows a new idea. Do not be disappointed. Someday you are bound to be rewarded if your theory is a good theory. I shall try to read your papers as soon as I can and discuss with my colleagues here in Grenoble. But the possible superconductivity in Swedenborgite structure with CuO4 tetradra is something purely experimental at the moment.

Hope I have not upset you by this comment.

Looking at the pictures in http://www.minsocam.org/ammin/AM20/AM20_492.pdf I can not see easily regular CuO2 plans. I think it is appropriate to verify the existence of such plans with the use of appropriate software, and if they exist, it is worthwhile to look for traces of superconductivity that can be done quickly at various workshops (including mine) with a SQUID magnetometer also with samples of a few tens of mg of powder.

It may be superconducting if there is a superconducting phase present. Experimental testing should be done and then if a superconducting phase is present try to get X-ray diffraction to see what phases are present. You might have normal conducting and superconducting phases in the same sample. Also, BCS theory does not explain HTSC. I understand the spin ladder theory was trying to do that.