TY - JOUR
T1 - Influence of Ni addition on the process of phase formation in MgB 2 bulk
AU - Zhao, Qian
AU - Liu, Yongchang
AU - Cai, Qi
PY - 2012/6
Y1 - 2012/6
N2 - Nickel is an important sheath material for the fabrication of MgB 2 wires. However, the effects of Ni doping on the phase formation and superconducting properties of MgB 2 remain controversial. In this work, Ni powder is selected for doping in MgB 2 bulk in order to examine the corresponding changes. Combining with the DSC analysis and in-situ XRD results, we find indications that the Ni powder reacted with Mg and B, forming MgNi 2.5B 2 at 600°C. The ternary compound began to decompose at a temperature above 800°C. The reactive phase, MgNi 2.5B 2, acted as an obstacle to the supercurrent flow, creating weak links among the MgB 2 grain boundaries. However, it is found that the added Ni formed a eutectic liquid phase with Mg at 506°C. The liquid phase helps the formation of MgB 2 at low temperature, which not only increases the density of the sample, but also improves the grain connectivity. Consequently, the presence of Ni in the MgB 2 sample is not necessarily a disadvantage; it depends on the desired application.
AB - Nickel is an important sheath material for the fabrication of MgB 2 wires. However, the effects of Ni doping on the phase formation and superconducting properties of MgB 2 remain controversial. In this work, Ni powder is selected for doping in MgB 2 bulk in order to examine the corresponding changes. Combining with the DSC analysis and in-situ XRD results, we find indications that the Ni powder reacted with Mg and B, forming MgNi 2.5B 2 at 600°C. The ternary compound began to decompose at a temperature above 800°C. The reactive phase, MgNi 2.5B 2, acted as an obstacle to the supercurrent flow, creating weak links among the MgB 2 grain boundaries. However, it is found that the added Ni formed a eutectic liquid phase with Mg at 506°C. The liquid phase helps the formation of MgB 2 at low temperature, which not only increases the density of the sample, but also improves the grain connectivity. Consequently, the presence of Ni in the MgB 2 sample is not necessarily a disadvantage; it depends on the desired application.
UR - http://www.scopus.com/inward/record.url?scp=84862804882&partnerID=8YFLogxK
U2 - 10.1007/s00339-012-6812-y
DO - 10.1007/s00339-012-6812-y
M3 - Article
AN - SCOPUS:84862804882
SN - 0947-8396
VL - 107
SP - 877
EP - 883
JO - Applied Physics A: Materials Science and Processing
JF - Applied Physics A: Materials Science and Processing
IS - 4
ER -