Vapor‐Deposited Borides of Group IVA Metals

The formation of vapor-deposited TiB2, ZrB2, and HfB2 at 1400°C was studied with respect to the influence of process variables on structure and stoichiometry. Stoichiometric, nonporous deposits of TiB2 were obtained; ZrB2 and HfB2 deposits contained β-rhombohedral boron. Precision lattice parameters were determined for the three diborides. The effect of codeposited boron on these parameters appeared to be slight. A small degree of preferred orientation existed in materials made under these conditions, indicating that crystallites tend to be deposited with c axes parallel to the substrate. Grain size, orientation, porosity, and stoichiometry are influenced and therefore should be controllable by process variation.