Mechanism of formation of the columnar structure in films of transition metal diborides

The formation of film coatings based on transition metal diborides was investigated using x-ray diffractometry and electron microscopy. A scheme of the transformation of the crystal lattice was proposed, and the corresponding interplanar distances were calculated. An analysis of the results obtained made it possible to describe qualitatively the mechanism of formation of a columnar structure of the films prepared from transition metal diborides by using tantalum diboride TaB2 as an example. It was demonstrated that, upon the synthesis of the films of the superstoichiometric composition, metal and nonmetal atoms have the octahedral coordination and form strong covalent bonds along the < 00.1 > direction, which favors texturing and the formation of a columnar structure. The results obtained were confirmed by the investigation of the physicomechanical characteristics of the films synthesized.