The Influence of Wire Heat Treatment on PIT Conductors Manufactured Using Laboratory-Made Boron

In this paper, we discuss the influence of heat treatment (applied to the wire as sintering for ex situ wire, or synthesis for in situ wire) on critical current density of MgB₂-based wires. A comparison of this influence (changing the synthesis/sintering parameters, i.e., time and temperature, applied to wire samples) for different manufacturing techniques has been given. Boron synthesized in our laboratory by magnesiothermic reduction has been used as precursor. In this paper, we show its behavior with different PIT manufacturing techniques. Different heat treatments of synthesis/sintering have been performed on short wires, to evaluate the suitable one for each manufacturing technique. Ex situ wire shows its best results in terms of J_c (10⁵ A/cm² at 2 T) after heat treatment at 920°C, while for in situ wires a heat treatment at 800°C was observed to be the best. A sample prepared following a mixed (ex-situ-in-situ) technique shows an independent .Ic behavior from the final heat treatment. Here, we report the .Ic analysis performed from transport and magnetic measurements by using Bean´s model for wire samples. The transport .Ic of the mixed sample shows the best behavior at high magnetic field, one order of magnitude higher than the ex situ wire.