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Title: Kinetics of the Topochemical Transformation of (PbSe)m(TiSe 2)n(SnSe 2)m(TiSe 2)n to (Pb0.5Sn0.5Se)m(TiSe2)n

Abstract

Solid-state reaction kinetics on atomic length scales have not been heavily investigated due to the long times, high reaction temperatures, and small reaction volumes at interfaces in solid-state reactions. All of these conditions present significant analytical challenges in following reaction pathways. Herein we use in situ and ex situ X-ray diffraction, in situ X-ray reflectivity, high-angle annular dark field scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy to investigate the mechanistic pathways for the formation of a layered (Pb0.5Sn0.5Se)1+δ(TiSe2)m heterostructure, where m is the varying number of TiSe2 layers in the repeating structure. Thin film precursors were vapor deposited as elemental-modulated layers into an artificial superlattice with Pb and Sn in independent layers, creating a repeating unit with twice the size of the final structure. At low temperatures, the precursor undergoes only a crystallization event to form an intermediate (SnSe2)1+γ(TiSe2)m(PbSe)1+δ(TiSe2)m superstructure. At higher temperatures, this superstructure transforms into a (Pb0.5Sn0.5Se)1+δ(TiSe2)m alloyed structure. The rate of decay of superlattice reflections of the (SnSe2)1+γ(TiSe2)m(PbSe)1+δ(TiSe2)m superstructure was used as the indicator of the progress of the reaction. Here, we show that increasing the number of TiSe2 layers does not decrease the rate at which the SnSe2 and PbSe layers alloy, suggesting that atmore » these temperatures it is reduction of the SnSe2 to SnSe and Se that is rate limiting in the formation of the alloy and not the associated diffusion of Sn and Pb through the TiSe2 layers.« less

Authors:
 [1];  [1];  [1];  [1];  [2]; ORCiD logo [1]
  1. Univ. of Oregon, Eugene, OR (United States)
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1524215
Report Number(s):
SAND-2019-5933J
Journal ID: ISSN 0002-7863; 675856
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 141; Journal Issue: 2; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Sutherland, Duncan R., Merrill, Devin R., Ditto, Jeffrey, Moore, Daniel B., Medlin, Douglas L., and Johnson, David C. Kinetics of the Topochemical Transformation of (PbSe)m(TiSe 2)n(SnSe 2)m(TiSe 2)n to (Pb0.5Sn0.5Se)m(TiSe2)n. United States: N. p., 2018. Web. doi:10.1021/jacs.8b10681.
Sutherland, Duncan R., Merrill, Devin R., Ditto, Jeffrey, Moore, Daniel B., Medlin, Douglas L., & Johnson, David C. Kinetics of the Topochemical Transformation of (PbSe)m(TiSe 2)n(SnSe 2)m(TiSe 2)n to (Pb0.5Sn0.5Se)m(TiSe2)n. United States. https://doi.org/10.1021/jacs.8b10681
Sutherland, Duncan R., Merrill, Devin R., Ditto, Jeffrey, Moore, Daniel B., Medlin, Douglas L., and Johnson, David C. Mon . "Kinetics of the Topochemical Transformation of (PbSe)m(TiSe 2)n(SnSe 2)m(TiSe 2)n to (Pb0.5Sn0.5Se)m(TiSe2)n". United States. https://doi.org/10.1021/jacs.8b10681. https://www.osti.gov/servlets/purl/1524215.
@article{osti_1524215,
title = {Kinetics of the Topochemical Transformation of (PbSe)m(TiSe 2)n(SnSe 2)m(TiSe 2)n to (Pb0.5Sn0.5Se)m(TiSe2)n},
author = {Sutherland, Duncan R. and Merrill, Devin R. and Ditto, Jeffrey and Moore, Daniel B. and Medlin, Douglas L. and Johnson, David C.},
abstractNote = {Solid-state reaction kinetics on atomic length scales have not been heavily investigated due to the long times, high reaction temperatures, and small reaction volumes at interfaces in solid-state reactions. All of these conditions present significant analytical challenges in following reaction pathways. Herein we use in situ and ex situ X-ray diffraction, in situ X-ray reflectivity, high-angle annular dark field scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy to investigate the mechanistic pathways for the formation of a layered (Pb0.5Sn0.5Se)1+δ(TiSe2)m heterostructure, where m is the varying number of TiSe2 layers in the repeating structure. Thin film precursors were vapor deposited as elemental-modulated layers into an artificial superlattice with Pb and Sn in independent layers, creating a repeating unit with twice the size of the final structure. At low temperatures, the precursor undergoes only a crystallization event to form an intermediate (SnSe2)1+γ(TiSe2)m(PbSe)1+δ(TiSe2)m superstructure. At higher temperatures, this superstructure transforms into a (Pb0.5Sn0.5Se)1+δ(TiSe2)m alloyed structure. The rate of decay of superlattice reflections of the (SnSe2)1+γ(TiSe2)m(PbSe)1+δ(TiSe2)m superstructure was used as the indicator of the progress of the reaction. Here, we show that increasing the number of TiSe2 layers does not decrease the rate at which the SnSe2 and PbSe layers alloy, suggesting that at these temperatures it is reduction of the SnSe2 to SnSe and Se that is rate limiting in the formation of the alloy and not the associated diffusion of Sn and Pb through the TiSe2 layers.},
doi = {10.1021/jacs.8b10681},
journal = {Journal of the American Chemical Society},
number = 2,
volume = 141,
place = {United States},
year = {Mon Dec 17 00:00:00 EST 2018},
month = {Mon Dec 17 00:00:00 EST 2018}
}

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Figures / Tables:

Figure 1 Figure 1: A schematic of the conversion of (PbSe)m(TiSe2)n(SnSe2)m(TiSe2)n into (Pbo.sSno.sSe)m(TiSe2)m, which involves the loss of Se and the interdiffusion of Sn and Pb through the intervening TiSe2 layers.

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