Search for content and authors
 

Effect of inhomogeneities of nanostructural magnesium diboride and SiC adding on critical current density

Tatiana Prikhna 1Artem Kozyrev 1Wolfgang Gawalek 2Yaroslav Savchuk 1Mikhael Wendt 2Nina Sergienko 1Viktor Moshchil 1Tobias Habisreuther 2Ulrikh Dittrich 3Sergey Dub 1Vladimir Melnikov 1Christa Schmidt 2Doris Litzkendorf 2Jan Dellith 2Peter Nagorny 1

1. V. Bakul Institute for Superhard Materials NAS of Ukraine, 2, Autozavodska str., Kiev 04074, Ukraine
2. Institut fuer Photonische Technologien (IPHT), Albert-Einstein-Strasse 9, Jena D07745, Germany
3. Starck GmbH, Goslar 38642, Germany

Abstract

In materials synthesized from Mg and B taken in the magnesium diboride stoichiometry under high-pressure 2 GPa in 973 K -1373 K temperature range the inhomogeneities  of size about 200 microns and below like as grains of magnesium dodecaborides and grains with higher oxygen concentration can be observed  The larger amount and finer distribution of dodecaboride grains correlate with higher pinning force and higher critical current density. On the one hand, an increase of the synthesis temperature leads to a decrease of the amount of magnesium dodecaboride in the structure and on the other provokes the segregation of oxygen-enriched phase into the fine homogeneously dispersed grains, which can promote pining as well. This can explain the fact that as the synthesis temperature increases from 1073 K to 1323 K, two local maximums of critical currents at the beginning and the end of this temperature range can be observed. 

The extremely high critical current densities were attained for the material with SiC added to the stoichiometric MgB2 mixture of magnesium and amorphous boron with 0.66 % of oxygen when synthesized at 2 GPa,  1050 oС for 1 h: in zero magnetic field it reached 1.6×106A/cm2 at 10 K and 1.24×106A/cm2 at 20 K,  was above 106 A/cm2 in the fields up to  2 and 1 T at 10 and 20 K, respectively, and higher than 105 A/cm2 in the fields up to 5 and 3.5 T at 10 and 20 K, respectively. The field of irreversibility at 20 KJ was higher than 8 Tand at 10 T in 10 T field the critical current density exceeded 1000 A/cm2. By adding SiC in the amount of 10 wt % in the case of synthesis at 1050 oC (under 2 GPa) the critical current density of the material can be increased by a factor of 1.4-10 (in magnetic fields from 0 to 10 T  at 10 K and in magnetic fields from 0 to 6 T at 20 K).

 

Legal notice
  • Legal notice:
 

Related papers

Presentation: Oral at E-MRS Fall Meeting 2008, Symposium I, by Artem Kozyrev
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-19 12:58
Revised:   2009-06-07 00:48