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Title: Applications and limitations of electron correlation microscopy to study relaxation dynamics in supercooled liquids

Abstract

Here, electron correlation microscopy (ECM) is a way to measure structural relaxation times, τ, of liquids with nanometer-scale spatial resolution using coherent electron scattering equivalent of photon correlation spectroscopy. We have applied ECM with a 3.5 nm diameter probe to Pt 57.5Cu 14.7Ni 5.3P 22.5 amorphous nanorods and Pd 40Ni 40P 20 bulk metallic glass (BMG) heated inside the STEM into the supercooled liquid region. These data demonstrate that the ECM technique is limited by the characteristics of the time series, which must be at least 40τ to obtain a well-converged correlation function g 2(t), and the time per frame, which must be less than 0.1τ to obtain sufficient sampling. A high-speed direct electron camera enables fast acquisition and affords reliable g 2(t) data even with low signal per frame.

Authors:
 [1];  [1];  [2];  [3];  [3];  [2];  [1]
  1. Univ. of Wisconsin, Madison, WI (United States)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  3. Yale Univ., New Haven, CT (United States)
Publication Date:
Research Org.:
Ames Lab., Ames, IA (United States); Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1374734
Report Number(s):
IS-J-9384; IS-J-9364
Journal ID: ISSN 0304-3991; PII: S030439911630184X
Grant/Contract Number:
AC02-07CH11358; DMR-1506564; MRSEC DMR 1119826; SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Ultramicroscopy
Additional Journal Information:
Journal Volume: 178; Journal Issue: C; Related Information: Also available at http://lib.dr.iastate.edu/ameslab_manuscripts/12/?utm_source=lib.dr.iastate.edu%2Fameslab_manuscripts%2F12&utm_medium=PDF&utm_campaign=PDFCoverPages; Journal ID: ISSN 0304-3991
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Electron correlation microscopy; Supercooled liquid; Structural relaxation time; Metallic glass; In-situ heating

Citation Formats

Zhang, Pei, He, Li, Besser, Matthew F., Liu, Ze, Schroers, Jan, Kramer, Matthew J., and Voyles, Paul M. Applications and limitations of electron correlation microscopy to study relaxation dynamics in supercooled liquids. United States: N. p., 2016. Web. doi:10.1016/j.ultramic.2016.09.001.
Zhang, Pei, He, Li, Besser, Matthew F., Liu, Ze, Schroers, Jan, Kramer, Matthew J., & Voyles, Paul M. Applications and limitations of electron correlation microscopy to study relaxation dynamics in supercooled liquids. United States. doi:10.1016/j.ultramic.2016.09.001.
Zhang, Pei, He, Li, Besser, Matthew F., Liu, Ze, Schroers, Jan, Kramer, Matthew J., and Voyles, Paul M. 2016. "Applications and limitations of electron correlation microscopy to study relaxation dynamics in supercooled liquids". United States. doi:10.1016/j.ultramic.2016.09.001. https://www.osti.gov/servlets/purl/1374734.
@article{osti_1374734,
title = {Applications and limitations of electron correlation microscopy to study relaxation dynamics in supercooled liquids},
author = {Zhang, Pei and He, Li and Besser, Matthew F. and Liu, Ze and Schroers, Jan and Kramer, Matthew J. and Voyles, Paul M.},
abstractNote = {Here, electron correlation microscopy (ECM) is a way to measure structural relaxation times, τ, of liquids with nanometer-scale spatial resolution using coherent electron scattering equivalent of photon correlation spectroscopy. We have applied ECM with a 3.5 nm diameter probe to Pt57.5Cu14.7Ni5.3P22.5 amorphous nanorods and Pd40Ni40P20 bulk metallic glass (BMG) heated inside the STEM into the supercooled liquid region. These data demonstrate that the ECM technique is limited by the characteristics of the time series, which must be at least 40τ to obtain a well-converged correlation function g2(t), and the time per frame, which must be less than 0.1τ to obtain sufficient sampling. A high-speed direct electron camera enables fast acquisition and affords reliable g2(t) data even with low signal per frame.},
doi = {10.1016/j.ultramic.2016.09.001},
journal = {Ultramicroscopy},
number = C,
volume = 178,
place = {United States},
year = 2016,
month = 9
}

Journal Article:
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  • We compare the dielectric response of ionic glasses and dipolar liquids near the glass transition. Our work is divided into two parts. In the first section we examine ionic glasses and the two prominent approaches to analyzing the dielectric response. The conductivity of ion-conducting glasses displays a power law dispersion {sigma}({omega}){proportional_to}{omega}{sup n}, where n{approx}0.67, but frequently the dielectric response is analyzed using the electrical modulus M{sup {asterisk}}({omega})=1/{var_epsilon}{sup {asterisk}}({omega}), where {var_epsilon}{sup {asterisk}}({omega})={var_epsilon}({omega}){minus}i{sigma}({omega})/{omega} is the complex permittivity. We reexamine two specific examples where the shape of M{sup {asterisk}}({omega}) changes in response to changes in (a) temperature and (b) ion concentration, to suggestmore » fundamental changes in ion dynamics are occurring. We show, however, that these changes in the shape of M{sup {asterisk}}({omega}) occur in the absence of changes in the scaling properties of {sigma}({omega}), for which n remains constant. In the second part, we examine the dielectric relaxation found in dipolar liquids, for which {var_epsilon}{sup {asterisk}}({omega}) likewise exhibits changes in shape on approach to the glass transition. Guided by similarities of M{sup {asterisk}}({omega}) in ionic glasses and {var_epsilon}{sup {asterisk}}({omega}) in dipolar liquids, we demonstrate that a recent scaling approach proposed by Dixon and co-workers for {var_epsilon}{sup {asterisk}}({omega}) of dipolar relaxation also appears valid for M{sup {asterisk}}({omega}) in the ionic case. While this suggests that the Dixon scaling approach is more universal than previously recognized, we demonstrate how the dielectric response can be scaled in a linear manner using an alternative data representation. {copyright} {ital 1997} {ital The American Physical Society}« less
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