1T-FeSe2 Layers in (PbSe)(1+d)(FeSe2)( n )?An Interlayer-Stabilized 2D Structure

The interactions between constituent layers in heterostructures provide opportunities to stabilize 2D structures that are not found in equilibrium phase diagrams. To computationally search for synthesizable heterostructures, an "island" approximation was used in the empty Pb-Fe-Se ternary phase diagram. Candidate Fe-Se "islands" that mimic the nuclei of potential structures were placed between the bilayers of PbSe. Several candidate "islands" remained stable when computationally relaxed, including (PbSe)(1+d)(FeSe2)1. Utilizing this information, the first three members of this (PbSe)(1+d)(FeSe2) n family of compounds were synthesized using designed precursors with nanoarchitectures that match the predicted compounds. Controlling the number of atoms of each element in each deposited layer in the precursor to be near the number required to form crystalline monolayers was essential to nucleate and grow these compounds rather than more thermodynamically stable phases. The combination of the computational "island" approach with the ability to prepare precursors with the designed nanoarchitecture works synergistically to overcome the challenges of synthesizing predicted heterostructures containing new constituent structures.