Effect of La Doping on Microstructure and Critical Current Density of MgB2

TL;DR

This study investigates how La doping influences the microstructure and critical current density of MgB2 superconductors, revealing optimal doping levels that enhance flux pinning and superconducting performance.

Contribution

It provides new insights into the effects of LaB6 nanoparticle inclusions on flux pinning and critical current density in MgB2 superconductors.

Findings

LaB6 nanoparticles are embedded within MgB2 grains.

Optimal doping (x=0.03) significantly enhances Jc.

Maximum Jc achieved is ~1.4x10^7 A/cm^2 at 5K.

Abstract

In the present study, La-doped MgB_2 superconductors with different doping level (Mg1-xLaxB2; x=0.00, 0.01, 0.03 & 0.05) have been synthesized by solid-state reaction route at ambient pressure. Effect of La doping have been investigated in relation to microstructural characteristics and superconducting properties, particularly intragrain critical current density (Jc). The microstructural characteristics of the as synthesized Mg(La)B2 compounds were studied employing transmission electron microscopic (TEM) technique. The TEM investigations reveal inclusion of LaB6 nanoparticles within the MgB2 grains which provide effective flux pinning centres. The evaluation of intragrain Jc through magnetic measurements on the fine powdered version of the as synthesized samples reveal that Jc of the samples change significantly with the doping level. The optimum result on Jc is obtained for Mg0.97La0.03B2 at 5K, the Jc reaches ~1.4x107A/cm2 in self field, ~2.1 x 106A/cm2 at 1T, ~2.5 x 105A/cm2 at 2.5T and ~1.8 x 104 A/cm2 at 4.5T. The highest value of intragrain Jc in Mg0.97La0.03B2 superconductor has been attributed to the inclusion of LaB6 nanoparticles which are capable of providing effective flux pinning centres.