Electronic Structure of VxTi1–xSe2 Solid Solutions with the (V,Ti)Se2 Structural Fragments

The equilibrium boundary for the layered VxTi1–xSe2 solid solution was determined according to a set of experimental data of synchrotron radiation X-ray photoelectron spectroscopy and electromotive force of the Li|Li+|VxTi1–xSe2 electrochemical cells. This boundary appears to be 20 mol % of V (x = 0.2). The formation of the VSe2 structural fragments, which are tightly bounded with VxTi1–xSe2 layers, appears at x > 0.2. A combined analysis of the Fermi-surface maps and the atomic force microscopy images reveals that the (001) planes in VSe2 and VxTi1–xSe2 structural fragments are parallel to each other. At the same time, these fragments demonstrate turbostratic disordering within the basal plane. The formation of such pseudo-homogeneous materials is associated with the contribution of the free surface energy, which is relatively high in the quasi-two-dimensional materials.