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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

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/jacs.8b10681· OSTI ID:1524215
 [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)
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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.

Research Organization:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC04-94AL85000
OSTI ID:
1524215
Report Number(s):
SAND-2019-5933J; 675856
Journal Information:
Journal of the American Chemical Society, Vol. 141, Issue 2; ISSN 0002-7863
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 2 works
Citation information provided by
Web of Science

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