Ruthenium boride

Ruthenium borides are compounds of ruthenium and boron. Their most remarkable property is potentially high hardness. Vickers hardness H_V = 50 GPa was reported for thin films composed of RuB₂ and Ru₂B₃ phases.^[1] This value is significantly higher than those of bulk RuB₂ or Ru₂B₃, but it has to be confirmed independently, as measurements on superhard materials are intrinsically difficult. For example, note that the initial report on extreme hardness of related material rhenium diboride^[2] was probably too optimistic.^[3]

Structure of orthorhombic RuB₂. Green atoms are Ru, pink - boron

Structure

Ruthenium diboride was first thought to have a hexagonal structure,^[4] as in rhenium diboride, but it was later tentatively determined to possess an orthorhombic structure.^[5]