1D-confined crystallization routes for tungsten phosphides

TL;DR

This study reveals diameter-dependent phase selectivity in 1D-confined tungsten phosphides during nanowire synthesis, combining experimental microscopy and theoretical modeling to uncover a new crystallization route for topological materials.

Contribution

It introduces a novel understanding of 1D-confined crystallization routes and phase bifurcation in tungsten phosphides based on nanowire diameter and surface energy considerations.

Findings

Phase bifurcation at ~35 nm diameter nanowires.

Diameter-dependent phase selectivity for tungsten phosphides.

Agreement between experimental phase diagram and theoretical calculations.

Abstract

Topological materials confined in one-dimension (1D) can transform computing technologies, such as 1D topological semimetals for nanoscale interconnects and 1D topological superconductors for fault-tolerant quantum computing. As such, understanding crystallization of 1D-confined topological materials is critical. Here, we demonstrate 1D-confined crystallization routes during template-assisted nanowire synthesis where we observe diameter-dependent phase selectivity for topological metal tungsten phosphides. A phase bifurcation occurs to produce tungsten monophosphide and tungsten diphosphide at the cross-over nanowire diameter of ~ 35 nm. Four-dimensional scanning transmission electron microscopy was used to identify the two phases and to map crystallographic orientations of grains at a few nm resolution. The 1D-confined phase selectivity is attributed to the minimization of the total surface energy, which depends on the nanowire diameter and chemical potentials of precursors. Theoretical calculations were carried out to construct the diameter-dependent phase diagram, which agrees with experimental observations. Our find-ings suggest a new crystallization route to stabilize topological materials confined in 1D.