title: Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures.
abstract: Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Caskey
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Holder
authors.affiliation: Colorado School of Mines, Golden, Colorado 80401, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Shulda
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Christensen
authors.affiliation: Colorado School of Mines, Golden, Colorado 80401, USA.
authors.forename: David
authors.initials: D
authors.lastname: Diercks
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Craig P
authors.initials: CP
authors.lastname: Schwartz
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: David
authors.initials: D
authors.lastname: Biagioni
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Nordlund
authors.affiliation: Tel Aviv University, Tel Aviv-Yafo, Israel.
authors.forename: Alon
authors.initials: A
authors.lastname: Kukliansky
authors.affiliation: Tel Aviv University, Tel Aviv-Yafo, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Natan
authors.affiliation: Lawrence Berkeley National Laboratory, Berkley, California 94720, USA.
authors.forename: David
authors.initials: D
authors.lastname: Prendergast
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Orvananos
authors.affiliation: Lawrence Berkeley National Laboratory, Berkley, California 94720, USA.
authors.forename: Wenhao
authors.initials: W
authors.lastname: Sun
authors.affiliation: University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Xiuwen
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Lawrence Berkeley National Laboratory, Berkley, California 94720, USA.
authors.forename: Gerbrand
authors.initials: G
authors.lastname: Ceder
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Ginley
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: William
authors.initials: W
authors.lastname: Tumas
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Perkins
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Vladan
authors.initials: V
authors.lastname: Stevanovic
authors.affiliation: Colorado School of Mines, Golden, Colorado 80401, USA.
authors.forename: Svitlana
authors.initials: S
authors.lastname: Pylypenko
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Stephan
authors.initials: S
authors.lastname: Lany
authors.affiliation: Colorado School of Mines, Golden, Colorado 80401, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Richards
authors.affiliation: National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
authors.forename: Andriy
authors.initials: A
authors.lastname: Zakutayev
mesh_terms: D003460:Crystallization; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D011789:Quantum Theory; D014001:Tin / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D009570:Nitriles; D014001:Tin