The data and source codes for the paper [J.H.*, J.-H.B.*, H.J., H.-Y.P., S.L., S.J.H., H.C., M.K.C., J.K., J.K., Y.S., H.J., J.S., S.-C.K., H.-K.R., K.H.L., H.-S.K., K.Y.C., C.W.Y., K.L., S.H.K., J.-P.A., H.B., G.H.K., B.H., S.J., T.H., J.P., C.Y.S., Y.Y., Y.-S.L., S.J.Y. and D.W.C., "Metastable Hexagonal Close-Packed Palladium Hydride in Liquid Cell TEM", Nature 603, 631 (2022).] are posted below.
Metastable phases—kinetically favored structures—are ubiquitous in nature. Rather than forming thermodynamically stable ground-state structures, crystals grown from high-energy precursors often initially adopt metastable structures depending on the initial conditions, such as temperature, pressure, or crystal size. As the crystals grow further, they typically undergo a series of transformations from metastable phases to lower-energy and ultimately energetically stable phases. Metastable phases sometimes exhibit superior physicochemical properties, and hence, the discovery and synthesis of novel metastable phases are promising avenues for innovations in materials science. However, the search for metastable materials has mainly been heuristic, performed on the basis of experiences, intuitions, or even speculative predictions, namely “rules of thumb.” This limitation necessitates the advent of a new paradigm to discover novel metastable phases based on rational design. Such design rule is embodied in the discovery of a metastable hexagonal close-packed (HCP) palladium hydride (PdHx) synthesized in a liquid cell transmission electron microscope. The metastable HCP structure is stabilized through a unique interplay among the precursor concentrations in the solution: a sufficient supply of hydrogen (H) favors the HCP structure on the sub-nanometer scale, and an insufficient supply of Pd inhibits further growth and subsequent transition toward the thermodynamically stable face-centered cubic (FCC) structure. These findings provide new thermodynamic insights into metastability engineering strategies to be deployed in discovering new metastable phases.
1. Denoised and aligned tilt series images and finalized tilt angles.
2. 3D tomographic reconstruction of a HCP-PdH nanoparticle.
3. Final atomic structure of a HCP-PdH nanoparticle.
4. HCP stacking type information and each coordinate data of a HCP-PdH nanoparticle.
5. Domain clustering and fitting data of a HCP-PdH nanoparticle.
6. Source codes for the atom tracing, determining HCP stacking type, clustering domain and fitting.