Modeling Sub- and Super-ambient Heat Capacities of the Group Iva Compounds despite the Lanthanide Contraction

This paper is concerned with the estimation of heat capacities in the IVA 3d-transition element compounds using especially Zr and Hf compounds as examples. Most prediction schemes routinely tacitly assume that volumes and masses trend ‘in parallel’. However, the lanthanide contraction here ensures for ZrX/HfX systems – and generally elsewhere – that this is not so in this portion of the periodic table. Available methods such as Latimer’s, Volumetric Priority, KomadaWestrum, Grimvall’s, and Sommers’ are compared on IVA elements and compounds. Only the Sommers approach has volumetric input. It provides the best prediction.