Structure and Properties of MgB2: Effect of Ti-O and TiC Additions

The effects of the additions of powdered titanium carbide (TiC) and polyvalent titanium oxides (Ti-O) to MgB 2 (synthesized under high pressure (2 GPa)–high temperature (800 and 1050 °C) conditions) on the critical current density,  j c , critical magnetic fields, B C2 and B irr , and the related transformations in the materials structures are reported in this paper. The superconducting characteristics are compared with that of MgB 2 with titanium (Ti) additions synthesized under the same conditions. The synthesis temperature, the ability of Ti-containing compounds to act as a getter, and the different diffusion rates of Mg and B into grains of these additions influence the distribution of the elements (boron, magnesium, and impurity oxygen) in the structures of MgB 2 -based materials. This in turn affects the formation of pinning centers, the resulting flux pinning and eventually the superconducting properties ( j c , B C2 , B irr ).