Real-time atomistic observation of structural phase transformations in individual hafnia nanorods

Bethany M. Hudak; Sean W. Depner; Gregory R. Waetzig; Anjana Talapatra; Raymundo Arroyave; Sarbajit Banerjee; Beth S. Guiton

doi:10.1038/ncomms15316

Real-time atomistic observation of structural phase transformations in individual hafnia nanorods

Bethany M. Hudak
, Sean W. Depner
, Gregory R. Waetzig
, Anjana Talapatra
, Raymundo Arroyave
, Sarbajit Banerjee
, Beth S. Guiton

Research output: Contribution to journal › Article › peer-review

73 Scopus citations

Abstract

High-temperature phases of hafnium dioxide have exceptionally high dielectric constants and large bandgaps, but quenching them to room temperature remains a challenge. Scaling the bulk form to nanocrystals, while successful in stabilizing the tetragonal phase of isomorphous ZrO 2, has produced nanorods with a twinned version of the room temperature monoclinic phase in HfO 2. Here we use in situ heating in a scanning transmission electron microscope to observe the transformation of an HfO 2 nanorod from monoclinic to tetragonal, with a transformation temperature suppressed by over 1000°C from bulk. When the nanorod is annealed, we observe with atomic-scale resolution the transformation from twinned-monoclinic to tetragonal, starting at a twin boundary and propagating via coherent transformation dislocation; the nanorod is reduced to hafnium on cooling. Unlike the bulk displacive transition, nanoscale size-confinement enables us to manipulate the transformation mechanism, and we observe discrete nucleation events and sigmoidal nucleation and growth kinetics.

Original language	English
Article number	15316
Journal	Nature Communications
Volume	8
DOIs	https://doi.org/10.1038/ncomms15316
State	Published - May 12 2017

Bibliographical note

Publisher Copyright:
© The Author(s) 2017.

Funding

STEM work at ORNL was sponsored by U.S. DOE, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (B.M.H. and B.S.G.), and in part by ORNL's Center for Nanophase Materials Sciences (CNMS), which is an Office of Science User Facility (B.M.H.). Funding for this work was provided by NASA Kentucky under NASA Award No: NNX10AL96H (to B.M.H.), by the National Science Foundation under DMR 1504702 (to S.W.D., G.R.W. and S.B.), DMR 1455154 (to B.S.G.) and CMMI 1534534 (to R.A. and A.T.), and by the Air Force Office of Scientific Research under AFOSR-FA9550-16-1-0180 (to R.A. and A.T.).

Funders	Funder number
Kentucky Space Grant Consortium
ORNL's Center for Nanophase Materials Sciences
DOE Basic Energy Sciences
Division of Materials Sciences and Engineering
U.S. Department of Energy
Office of Science Programs
CNMS
National Science Foundation Arctic Social Science Program	CMMI 1534534, 1534534, DMR 1504702, 1455154, DMR 1455154
National Aeronautics and Space Administration	NNX10AL96H
Air Force Office of Scientific Research, United States Air Force	AFOSR-FA9550-16-1-0180

ASJC Scopus subject areas

General Chemistry
General Biochemistry, Genetics and Molecular Biology
General
General Physics and Astronomy

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10.1038/ncomms15316

Cite this

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title = "Real-time atomistic observation of structural phase transformations in individual hafnia nanorods",

abstract = "High-temperature phases of hafnium dioxide have exceptionally high dielectric constants and large bandgaps, but quenching them to room temperature remains a challenge. Scaling the bulk form to nanocrystals, while successful in stabilizing the tetragonal phase of isomorphous ZrO 2, has produced nanorods with a twinned version of the room temperature monoclinic phase in HfO 2. Here we use in situ heating in a scanning transmission electron microscope to observe the transformation of an HfO 2 nanorod from monoclinic to tetragonal, with a transformation temperature suppressed by over 1000°C from bulk. When the nanorod is annealed, we observe with atomic-scale resolution the transformation from twinned-monoclinic to tetragonal, starting at a twin boundary and propagating via coherent transformation dislocation; the nanorod is reduced to hafnium on cooling. Unlike the bulk displacive transition, nanoscale size-confinement enables us to manipulate the transformation mechanism, and we observe discrete nucleation events and sigmoidal nucleation and growth kinetics.",

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doi = "10.1038/ncomms15316",

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AU - Hudak, Bethany M.

AU - Depner, Sean W.

AU - Waetzig, Gregory R.

AU - Talapatra, Anjana

AU - Arroyave, Raymundo

AU - Banerjee, Sarbajit

AU - Guiton, Beth S.

PY - 2017/5/12

Y1 - 2017/5/12

N2 - High-temperature phases of hafnium dioxide have exceptionally high dielectric constants and large bandgaps, but quenching them to room temperature remains a challenge. Scaling the bulk form to nanocrystals, while successful in stabilizing the tetragonal phase of isomorphous ZrO 2, has produced nanorods with a twinned version of the room temperature monoclinic phase in HfO 2. Here we use in situ heating in a scanning transmission electron microscope to observe the transformation of an HfO 2 nanorod from monoclinic to tetragonal, with a transformation temperature suppressed by over 1000°C from bulk. When the nanorod is annealed, we observe with atomic-scale resolution the transformation from twinned-monoclinic to tetragonal, starting at a twin boundary and propagating via coherent transformation dislocation; the nanorod is reduced to hafnium on cooling. Unlike the bulk displacive transition, nanoscale size-confinement enables us to manipulate the transformation mechanism, and we observe discrete nucleation events and sigmoidal nucleation and growth kinetics.

AB - High-temperature phases of hafnium dioxide have exceptionally high dielectric constants and large bandgaps, but quenching them to room temperature remains a challenge. Scaling the bulk form to nanocrystals, while successful in stabilizing the tetragonal phase of isomorphous ZrO 2, has produced nanorods with a twinned version of the room temperature monoclinic phase in HfO 2. Here we use in situ heating in a scanning transmission electron microscope to observe the transformation of an HfO 2 nanorod from monoclinic to tetragonal, with a transformation temperature suppressed by over 1000°C from bulk. When the nanorod is annealed, we observe with atomic-scale resolution the transformation from twinned-monoclinic to tetragonal, starting at a twin boundary and propagating via coherent transformation dislocation; the nanorod is reduced to hafnium on cooling. Unlike the bulk displacive transition, nanoscale size-confinement enables us to manipulate the transformation mechanism, and we observe discrete nucleation events and sigmoidal nucleation and growth kinetics.

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JO - Nature Communications

JF - Nature Communications

M1 - 15316

ER -

Real-time atomistic observation of structural phase transformations in individual hafnia nanorods

Abstract

Bibliographical note

Funding

ASJC Scopus subject areas

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