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Nano SiC doped MgB2 bulk superconductor with Tc over 42 K by high gas pressure annealing

Andrzej J. Morawski 2Tomasz P. Łada 2Adam M. Presz 2Tadeusz Mazur 2Ryszard Diduszko 3,7Andrzej J. Zaleski 1Kazimierz Przybylski 4Silvia Bodoardo 6Valeria Dellarocca 5

1. Polish Academy of Sciences, Institute of Low Temperature and Structure Research (INTiBS), Okólna 2, Wrocław 50-422, Poland
2. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
3. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
4. AGH University of Science and Technology (AGH), al. Mickiewicza 30, Kraków 30-059, Poland
5. Dipartimento di Fisica, Politecnico di Torino, Italy, corso Duca degli Abruzzi, 24, Torino 10129, Italy
6. Politecnico di Torino - Dipartimento di Scienze dei Materiali e Ingegneria Chimica, Duca degli Abruzzi 24, Torino 10129, Italy
7. Industrial Institute of Electronics (PIE), Dluga, Warszawa 00-241, Poland


Since affirm that the MgB2 is a potentially promising material for the large-scale application as superconducting devices, the proper doping substance that can increase the Jc or Tc has been intensively searched. One of the most interesting doping argent is nano-SiC powder.
We investigated the effect of the nano-powder SiC doping of two average grade batches: 6 nm and 18 nm, with the content up to 10 at. % for the commercial MgB2 powder made by Alfa Aesar.
The syntheses have been made on the cylindrical samples of 3 mm in diameter and 5 to 7 mm in length. Such samples were obtained by uni-axial pressing at 1.5 GPa in three sectors open anvils.
Synthesis were made at an inert gas at pressure of up to 1 GPa at temperature from 1500 K to 1550 K, in the high pressure gas trap system, with the equilibrium magnesium vapor made by the melting of Mg chips inside close vessels, during the experiment lasting for two hours.
As obtained samples thus were superconducting with Tc over 39 K and the highest Tc at 42.6 K was recorded for the sample doped with 1.5 at % of the 6nm SiC. The XRD examinations indicated the MgB2 phase and a very low addition of Mg, Si and C composites and/or SiC as well as Mg2Si nano-crystallites. The compositions of the additional phase were strictly dependent of the nano-size grains dimensions (their solubility) and quantity. The lattice parameters for all samples were smaller than for pure MgB2 initial samples. The SEM, EDX and superconducting properties Hc2, Tc, Jc, were measured and discussed. The probably effect of tangential strain caused by nano-inclusion of thin amorphous or crystalline layer between the pure or carbon doped MgB2 larger grain are considered for increasing the Tc of our samples.


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Presentation: oral at E-MRS Fall Meeting 2004, Symposium E, by Andrzej J. Morawski
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-30 23:52
Revised:   2009-06-08 12:55