Enhanced critical current density (Jc) and fractural strength of low and high Eu level doped bare bulk (Bi, Pb)-2223 rods for cryogenic applications

•Investigated superconducting and mechanical properties of Eu doped bare bulk (Bi, Pb)−2223 rods.•Jc increases 3 times in low fields for low Eu levels via inter-grain Eu.•Jc increases 6 times in high fields for high Eu level probably by intra-grain Eu.•σ value increases for both low and high Eu concentrations rods.•Long term reliability of these rods suitable for commercial use. The effect of Eu doping (0 to 0.12 M%) on magnetic field dependence of transport critical current density (Jc) and diametral fracture strength (σ) of the bare bulk 100 mm long (Bi, Pb)-2223 rods is reported. An enhancement in Jc on Eu doping has been observed for low Eu levels/low-magnetic fields and for high Eu levels in relatively high magnetic fields. The diametral fracture strength (σ) has also increased for both low and high Eu levels. In addition these studies, contact resistivity and magneto are also explored. Thermal cycling tests were performed 50 times to check the long term reliability of these rods by observing any degradation in Jc and contact resistivity which exhibits nearly no change in their values. The nature of flux pinning centers responsible for the low Eu level/ low field and high Eu level/high field has been discussed. The improvement in both the transport Jc as well as of σ by low/high Eu doping evidences long-term reliability and high importance for potential applications of these bare bulk (Bi, Pb)-2223 rods in low as well as high fields.