TY - GEN
T1 - Structure and functional properties of bulk MgB2 superconductors synthesized and sintered under pressure
AU - Prikhna, Tatiana
AU - Eisterer, Michael
AU - Gawalek, Wolfgang
AU - Mamalis, Athanasios
AU - Kozyrev, Artem
AU - Kovylaev, Valeriy
AU - Hristoforou, Evangelos
AU - Weber, Harald W.
AU - Noudem, Jacques
AU - Goldacker, Wilfried
AU - Moshchil, Viktor
AU - Chaud, Xavier
AU - Sokolovsky, Vladimir
AU - Shaternik, Anton
AU - Dellith, Jan
AU - Schmidt, Christa
AU - Habisreuther, Tobias
AU - Litzkendorf, Doris
AU - Dub, Sergey
AU - Borimskiy, Alexander
AU - Sergienko, Nina
AU - Sverdun, Vladimir
AU - Prisyazhnaya, Elena
PY - 2014/1/1
Y1 - 2014/1/1
N2 - The high pressure (50 MPa - 2 GPa) - high temperature synthesized MgB2 bulk materials are characterized by nearly theoretical density (1-2% porosity), 80-98% connectivity, extremely high critical current densities (e.g. at 20 K, in range of 0-1 T jc=1.3-1.0 MA·cm-2 (doped by 10% SiC) and jc= 0.92 - 0.73 MA·cm-2 (without doping)), large irreversibility fields (Birr (18.4 K) =15 T and Birr (0 K) = 32.5 T) and high upper critical fields (Bc2 (22 K) =15 T and Bc2(0 K) ~ 42.1 T). The transformation of the grain boundary pinning into the point one in MgB2-based materials caused by increasing manufacturing temperature from 800 to 1050 °C under an increase of pressures from 0.1 to 2 GPa correlates well with an increase in critical current density in low external magnetic fields. The critical current density increase is caused by the redistribution of boron and the oxygen impurities in the material structure. As the manufacturing temperature increases, the discontinuous oxygen enriched layers transform into distinct Mg-B-O inclusions and the size and amount of inclusions of higher magnesium borides MgBX (X>4) are reduced. The effect of oxygen and boron redistribution can be enhanced by Ti or SiC additions.
AB - The high pressure (50 MPa - 2 GPa) - high temperature synthesized MgB2 bulk materials are characterized by nearly theoretical density (1-2% porosity), 80-98% connectivity, extremely high critical current densities (e.g. at 20 K, in range of 0-1 T jc=1.3-1.0 MA·cm-2 (doped by 10% SiC) and jc= 0.92 - 0.73 MA·cm-2 (without doping)), large irreversibility fields (Birr (18.4 K) =15 T and Birr (0 K) = 32.5 T) and high upper critical fields (Bc2 (22 K) =15 T and Bc2(0 K) ~ 42.1 T). The transformation of the grain boundary pinning into the point one in MgB2-based materials caused by increasing manufacturing temperature from 800 to 1050 °C under an increase of pressures from 0.1 to 2 GPa correlates well with an increase in critical current density in low external magnetic fields. The critical current density increase is caused by the redistribution of boron and the oxygen impurities in the material structure. As the manufacturing temperature increases, the discontinuous oxygen enriched layers transform into distinct Mg-B-O inclusions and the size and amount of inclusions of higher magnesium borides MgBX (X>4) are reduced. The effect of oxygen and boron redistribution can be enhanced by Ti or SiC additions.
KW - Connectivity
KW - Critical current density
KW - High pressure
KW - Nanostructure
KW - Pinning centers
UR - http://www.scopus.com/inward/record.url?scp=84906724305&partnerID=8YFLogxK
U2 - 10.4028/www.scientific.net/MSF.792.21
DO - 10.4028/www.scientific.net/MSF.792.21
M3 - Conference contribution
AN - SCOPUS:84906724305
SN - 9783038350705
T3 - Materials Science Forum
SP - 21
EP - 26
BT - Applied Electromagnetic Engineering for Magnetic, Superconducting, Multifunctional and Nano Materials
PB - Trans Tech Publications Ltd
T2 - 8th Japanese-Mediterranean Workshop on Applied Electromagnetic Engineering for Magnetic, Superconducting, Multifunctional and Nano Materials, JAPMED 2013
Y2 - 23 June 2013 through 26 June 2013
ER -