High pressure and hot-pressing manufactured magnesium diboride. Inclusions of higher borides as possible pinning centers in the material

Properties of materials synthesized from Mg and B and sintered from MgB 2 using high-pressure (2 GPa) and hot-pressing (30 MPa) at 700- 1100 °C are discussed. The influence of Ta, Ti and Zr additions on the material structure and properties was studied. The average grain size of 15-37 nm was observed for materials produced under a pressure of 2 GPa. For high-pressure synthesized MgB 2 , the highest critical current densities known from literature have been obtained. Dispersed inclusions of higher borides with the stoichiometry close to MgB 12 and MgB 7 can act as pinning centers in the magnesium diboride material manufactured using high pressure and hot pressing.