Crystal chemistry of the series LnT₂B₂C (Ln rare earth, T transition element)

The new LuNi₂B₂C-type structure has been investigated for different lanthanide atoms and transition metal elements. Single-crystal structure determinations were carried out for some representative compounds, and a linear regression fit was used to infer the positional parameter of the boron atom for the whole rare earth series. In this way, detailed bonding information for all phases in the series was obtained. A geometric model, based on the conservation of bond lengths, explains the behaviour of the lattice parameters for the different size lanthanides.