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Title: Polymorphism in elemental silicon: Probabilistic interpretation of the realizability of metastable structures

Authors:
;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1408170
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 18; Related Information: CHORUS Timestamp: 2017-11-03 10:32:34; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Jones, Eric B., and Stevanović, Vladan. Polymorphism in elemental silicon: Probabilistic interpretation of the realizability of metastable structures. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.96.184101.
Jones, Eric B., & Stevanović, Vladan. Polymorphism in elemental silicon: Probabilistic interpretation of the realizability of metastable structures. United States. doi:10.1103/PhysRevB.96.184101.
Jones, Eric B., and Stevanović, Vladan. 2017. "Polymorphism in elemental silicon: Probabilistic interpretation of the realizability of metastable structures". United States. doi:10.1103/PhysRevB.96.184101.
@article{osti_1408170,
title = {Polymorphism in elemental silicon: Probabilistic interpretation of the realizability of metastable structures},
author = {Jones, Eric B. and Stevanović, Vladan},
abstractNote = {},
doi = {10.1103/PhysRevB.96.184101},
journal = {Physical Review B},
number = 18,
volume = 96,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 3, 2018
Publisher's Accepted Manuscript

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  • With few systems of technological interest having been studied as extensively as elemental silicon, there currently exists a wide disparity between the number of predicted low-energy silicon polymorphs and those that have been experimentally realized as metastable at ambient conditions. We put forward an explanation for this disparity wherein the likelihood of formation of a given polymorph under near-equilibrium conditions can be estimated on the basis of mean-field isothermal-isobaric (N,p,T) ensemble statistics. The probability that a polymorph will be experimentally realized is shown to depend upon both the hypervolume of that structure's potential energy basin of attraction and a Boltzmannmore » factor weight containing the polymorph's potential enthalpy per particle. Both attributes are calculated using density functional theory relaxations of randomly generated initial structures. We find that the metastable polymorphism displayed by silicon can be accounted for using this framework to the exclusion of a very large number of other low-energy structures.« less
  • The new metastable compound Cr{sub 1+x}Sb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni{sub 2}In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr{sub 1+x}Sb crystallized. A change in the activation energy was observed for the diffusion processmore » when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr{sub 1+x}Sb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr{sub 1.6}Sb in Ni{sub 2}In-type structure. • The new Cr-rich phase shows half-metallic behavior.« less
  • Five thermally interconvertible polymorphs of 1,3,5,7-tetranitro-3,7-diazabicyclo(3.3.1)nonane (TNDBN) were discovered between 163 and 490 K by using variable-temperature FTIR spectroscopy and differential thermal analysis. Some probable structural differences between several of the polymorphs can be ascertained from the IR spectra. The structure of one of the polymorphs was determined by single crystal x-ray diffraction: orthorhombic, Pbca, a = 14.639 (3) A, b = 15.485 (2) A, c = 21.576 (5) A, Z = 16, R/sub F/ = 0.047, R/sub wF/ = 0.049. The asymmetric unit consists of two independent molecules; in one the nitroamine groups are exo/exo, in the other exo/endo.more » In the exo/exo molecule one of the C-bound NO/sub 2/ groups is rotationally disordered. Polymorphism, not previously known, was discovered in 3,7-dinitro-1,3,5,7-tetrazabicyclo(3.3.1)nonane (DPT). The slow thermal decomposition of solid TNDBN and DPT was analyzed by IR spectroscopy. Concentration-time and concentration-pressure profiles for the gas products formed by high heating rate thermal decomposition were also constructed. The distribution of products from TNDBN differs significantly from DPT but is understandable in terms of the compositional differences. The importance of the unit A is discussed.« less