RESEARCH ARTICLE Nanoscience and Nanotechnology Volume 1 Issue 1 | 2018 | 1 Research article for journal of nanoscience and nanotechnology Asaf Tolga ULGEN 1 Department of Electric and Electronic Engineering, Faculty of Engineering, Sirnak University, Sirnak 73000, Turkey, ulgen_at@sirnak.edu.tr Abstract: Aim: In the present study, I have investigated the effect of different annealing time durations of 0.5h, 1h, 2h and 4h (annealing temperature at 700 o C) on the electrical, micro structural and superconducting properties of the nano hexagonal boron nitride (hBN) added/doping magnesium diboride (MgB2) superconducting samples. The aim of this work, hBN added MgB2 superconducting bulk samples are determined to find out the optimum sintering time, also investigated how BN addition effects the optimum fabrication conditions. These superconducting samples were prepared by the conventional solid-state reaction method. Experimental techniques of X-ray diffraction (XRD) were used for structural and microstructural examinations. Critical transition temperatures, difference between Tc-onset and Tc-offset, a and c lattice parameter, grain size, bulk density, residual resistivity ratios (RR) and cross-sectional area fractions (AF) of the pure and nano-hBN added MgB2 materials are obtained using a cryostat equipped with a superconducting magnet. All the experimental results notice that the characteristic features improve regularly with the increment in sintering time durations. Keywords: nano material (Boron Nitride); superconductivity; X-ray diffraction; micro structural; lattice parameters. 1. Introduction The scientific and development researches on the characteristic features of superconducting material have effectively been continued global. The discovery of superconductivity at high critical transition temperature (Tc=39 K) in MgB2 has attracted much interest researchers and solid-state physics [1,2] . Due to its relatively high Tc, low cost and transparency of the grain boundaries to the current flow, MgB2 superconductor is a suitable candidate for large scale applications [3] . Unlike High Temperature Superconductors (HTS), MgB2 has simple chemical composition and hexagonal AlB2-type crystal structure (space group P6/mmm). In addition, these superconductor sample has a a high critical current density (Jc), high irreversibility field (µ0Hirr) and very high upper critical field (µ0Hc2) in the metallic superconductors [4-6] . As the molecular formula states, MgB2 hexagonal close-packed structure is composed of a ratio of one magnesium atom to two boron atoms and the bonding between the atoms is a mix of ionic, covalent and metallic bonds [7] . A number of techniques were applied for fabrication of practical MgB2 conductors during last 17 years. The chemical doping [8-10] , substitution [11,12] , evaporation [13,14] and changing preparation condition [15-17] have extensively been used to improve the mechanical, microstructural, superconducting and magnetic properties of the MgB2 material. Fabrication of MgB2 samples in bulk, wire and tape forms is a complicated process. Preparation of MgB2 based superconductors using commercial MgB2 is known as ex-situ. In the ex-situ method, commercially available reacted MgB2 powder is used and the main advantage of this method over in situ method is the higher density of the final product. However, the important disadvantage of this ex-situ is the poor grain connectivity [18] . Planetary ball milling of the precursor powder, which leads to fine grains of MgB2 and distributes the MgO inclusions more evenly, both have positive effects on improving the connectivity, flux pinning and Jc [19] . Sintering at high temperature 800−1000 o C [20] and ball milling [21] of the Copyright © 2018 Asaf Tolga ULGEN. doi: 10.18686/nn.v1i1. This is an open-access article distributed under the terms of the Creative Commons Attribution Unported License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.