Effect of different-sized h-BN nano-particles on some properties of MgB2 superconductors

The present study reports the effect of hexagonal boron nitride (h-BN) doping on the superconducting properties of bulk MgB2 samples. Structural, electrical and magnetic properties of 3 wt% h-BN doped MgB2 samples are studied in terms of three different sized h-BN nanoparticles. The results show that h-BN doping has no significant change on critical transition temperature (+/- 0.5 K deviation), but decreases the magnetic J (c) with increasing the h-BN particle size. Among the doped samples, a highest J (c) (T = 10 K) value of 1.8 x 10(4) A/cm(2) is achieved for the sample doped with the smallest sized h-BN at zero external magnetic field but it is still lower than the 2.5 x 10(4) A/cm(2) obtained for the un-doped sample. In the scope of this study, it is investigated whether or not the nano-sized h-BN particle is a possible candidate to improve the pinning properties of the MgB2 sample and we suggest that particle size is very important parameter in h-BN doping into MgB2.