I have prepared BSCCO pallet, however, the prepared pallet shows resistance at room temperature in Mega ohms can anyone help me know the possibility where I can make the correction?
The prepared samples were calcined at different stages up to 800 degrees. We want to know how we can reduce the resistance in the material. Is oxygenation a solution?
Hello Dinesh,
RT resistance in the range of MegaOhms says someting is wrong.
The RT resistivity should be in the range ~1 to 8 mOhm.cm depending on texture and O contents.
A few questions to clarify your observations:
What BSCCO have you prepared (Bi2201, Bi2212, or Bi2223)?
Do you have XRD evidence for that?
How did you make contacts?
Mark
Dear Sir
@MARK, I am still to do XRD analysis and thus I do not know the phase yet. However, I expected low resistance when checked with a multimeter probes (just pressure contact). I wanted to ensure that the resistivity was good enough to carry out rho vs T measurement in LN2, I am preparing now another set of samples (pallets), meanwhile, my XRD results will soon be available. I would like to know if this is because of the low oxygen content, if so, can it be sorted out by annealing under O2 flow, if yes, what temperature should I use for annealing under O2?
I will right back to you once I get my XRD pattern ready.
thanks,
Dinesh
What was your intention in BSCCO (2201, 2212 or 2223)?.
If you work with 2212, the resistance of an order of MegaOhms is not due to O contents. This is something else.
Take a small piece of indium and rub it into the pallet,at the point of contact with a scalpel until indium diffuses. Then make new measurement of resistivity.
@Mark
Dear Sir,
I am working with 2212 BSCCO. (Sorry for the delay in writing back to you.) I have repeated the anealling process where the highest temperature of annealing was 880 degrees. The resistance is showing as around 600 ohms (this on a pallet of 10 mm dia X 1mm thickness). Is it okay now?
Sincerely,
Dinesh
@ Olga Ivanenko,
Dear Ma'am,
The measurement set up is in four probe configuration where the contact are made of indium past and Cu wires. The values of resistance has gone down to 600 ohms. (I think it is due to the annealing process that I 've used rather than the electrical contacts ). Need your valuable suggestion in this matter.
Sincerely,
Dinesh
Dear Dinesh,
we have synthesized 2212 BSCCO of a mixture of oxides. The calcination was performed at 760 degrees for 10 h in air. Then the mixture was ground and pressed into discs.. Then synthesis was performed at 820 degrees in air .
Best wishes ,
Olga
Dear Dinesh,
600 Ohms is still high.
The RT resistivity of Bi2212 within the ab plane is ~ 0.3 to 2 mOhm.cm;
depending on the O partial pressure
[Yamada et al 2007 Physica C 460-2; pp 815-816]
The RT resistivity of Bi2212 along the c axis is ~ 1 Ohm.cm;
[Krusin-Elbaum et al et al 2003 Physica C 387 pp 169-174]
-----------------
The annealing temperature of 880°C in air could be too high.
It is likely that some partial meting of Bi2212 occurs.
Then the result depends on how slow is your cooling.
There could be also a reaction with the material of crucible.
What crucible do you use?
Cheers,
Mark
Dear sir,
@Dinesh, I had the same problem in the process of my experiment, the BSCCO (2212, 0.5 mm dia X 20 micron) shows Mega ohms at RT temperature. I make the contact with silver paint and gold wire. So, I'd like to know how you fix this in the end.
Cheers,
Weijian Lou
@Olega
I think so, and I tried indium as you mentioned before, still not working
Weijian,
How did you prepare such a specimen (0.5 mm dia X 20 micron = 500x20 µm )?
Did you machine it from a pellet or punch the thin film on some substrate?
Mark
The electrical contacts must be attached to the BSCCO pallet with silver paint.
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