High Field Performance of Nano-Diamond Doped MgB2 Superconductor

TL;DR

This study demonstrates that nano-diamond doping in MgB2 superconductors enhances high-field performance and irreversibility fields without significantly affecting Tc up to a certain doping level, showing promising improvements for practical applications.

Contribution

It introduces nano-diamond doping as an effective method to significantly improve the high-field superconducting properties of MgB2, with detailed analysis of doping effects.

Findings

Irreversibility field Hirr increased from 7.5 T to 13.5 T with 3-wt% nD doping.

Jc at 10 K and 6 T is 40 times higher in doped samples than pure MgB2.

Doped samples maintain higher Jc values at elevated magnetic fields and temperatures.

Abstract

Polycrystalline MgB2-nDx (x= 0 to 0.1) samples are synthesized by solid-state route with ingredients of Mg, B and n-Diamond. The results from magneto-transport and magnetization of nano-diamond doped MgB2-nDx are reported. Superconducting transition temperature (Tc) is not affected significantly by x up to x = 0.05 and latter decreases slightly for higher x > 0.05. R(T) vs H measurements show higher Tc values under same applied magnetic fields for the nano-diamond added samples, resulting in higher estimated Hc2 values. From the magnetization measurements it was found that irreversibility field value Hirr for the pristine sample is 7.5 Tesla at 4 K and the same is increased to 13.5 Tesla for 3-wt% nD added sample at the same temperature. The Jc(H) plots at all temperatures show that Jc value is lowest at all applied fields for pristine MgB2 and the sample doped with 3-wt% nD gives the best Jc values at all fields. For the pure sample the value of Jc is of the order of 105 A/cm2 at lower fields but it decreases very fast as the magnetic field is applied and becomes negligible above 7 Tesla. The Jc is 40 times higher than pure MgB2 at 10 K at 6 Tesla field in case of 3%nD doped sample and its value is still of the order of 103 A/cm2 at 10 Tesla for the same sample. On the other hand at 20K the 5%nD sample shows the best performance at higher fields. These results are discussed in terms of extrinsic pinning due to dispersed n-Diamond in the host MgB2 matrix along with the intrinsic pinning due to possible substitution of C at Boron site and increased inter-band scattering for highly doped samples resulting in extraordinary performance of the doped system.