Some Issues of Magnesium Diboride Bulk Samples’ Obtaining Process

摘要

Magnesium diboride bulk superconductor samples (targets) with a >50 mm diameter have beenobtained in an induction furnace using hot pressing and spark-plasma synthesis methods. These methodsenable to obtain small-diameter (up to <10 mm) samples without any difficulties by gradual temperatureincrease 20-1050°C. The samples with an increased diameter (>50 mm) reveal a number of problems.Despite the fact that big-diameter samples’ phase content is like that of small ones, their porosity is increasedand 45-50 % of the obtained samples produce macro cracks, and in some cases the samples may becompletely destroyed. Bulk samples were obtained in optimal condition at 600-1050°C in induction furnace.The samples’ Tc = 38.5-39K.