Univ. of Kentucky, Lexington, KY (United States). Dept. of Chemistry
Univ. at Buffalo, NY (United States). Dept. of Chemistry
Texas A & M Univ., College Station, TX (United States). Dept. of Chemistry. Dept. of Materials Science and Engineering
Texas A & M Univ., College Station, TX (United States). Dept. of Materials Science and Engineering
Univ. of Kentucky, Lexington, KY (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
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 ZrO2, has produced nanorods with a twinned version of the room temperature monoclinic phase in HfO2. Here we use in situ heating in a scanning transmission electron microscope to observe the transformation of an HfO2 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.
Hudak, Bethany M., Depner, Sean W., Waetzig, Gregory R., Talapatra, Anjana, Arroyave, Raymundo, Banerjee, Sarbajit, & Guiton, Beth S. (2017). Real-time atomistic observation of structural phase transformations in individual hafnia nanorods. Nature Communications, 8. https://doi.org/10.1038/ncomms15316
Hudak, Bethany M., Depner, Sean W., Waetzig, Gregory R., et al., "Real-time atomistic observation of structural phase transformations in individual hafnia nanorods," Nature Communications 8 (2017), https://doi.org/10.1038/ncomms15316
@article{osti_1376500,
author = {Hudak, Bethany M. and Depner, Sean W. and Waetzig, Gregory R. and Talapatra, Anjana and Arroyave, Raymundo and Banerjee, Sarbajit and Guiton, Beth S.},
title = {Real-time atomistic observation of structural phase transformations in individual hafnia nanorods},
annote = {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 ZrO2, has produced nanorods with a twinned version of the room temperature monoclinic phase in HfO2. Here we use in situ heating in a scanning transmission electron microscope to observe the transformation of an HfO2 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.},
doi = {10.1038/ncomms15316},
url = {https://www.osti.gov/biblio/1376500},
journal = {Nature Communications},
issn = {ISSN 2041-1723},
volume = {8},
place = {United States},
publisher = {Nature Publishing Group},
year = {2017},
month = {05}}
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Aeronautics and Space Administration (NASA) (United States); National Science Foundation (NSF) (United States); Air Force Office of Scientific Research (AFOSR) (United States)