LAUSR

The formation of the ferecrystalline compound (SnSe)1.15VSe2 is studied utilizing complementary X-ray diffraction techniques, differential scanning calorimetry, compositional analysis, scanning transmission electron microscopy, and X-ray absorption spectroscopy. A careful analysis unravels the formation mechanism, where a simultaneous crystallization of the individual constituents goes hand in hand with the formation of the superlattice structure. SnSe2 monolayers form along with SnSe and VSe2 units in the superlattice during the formation of (SnSe)1.15VSe2, with the SnSe2 monolayers coexisting up to 300°C. An annealing temperature of 400°C is required to fully self-assemble the ferecrystalline compound (SnSe)1.15VSe2, composed of alternating rocksalt-like SnSe bilayers and VSe2 trilayers. These results demonstrate a complex pathway along a multi-valley energy landscape for these metastable compounds, which in turn offers a rich platform to synthesize targeted layering sequences by precisely controlling the composition of the precursors as well as the annealing conditions.