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Title: Tailoring nanopore formation in atomic layer deposited ultrathin films [Nanopore formation in atomic layer deposited ultrathin films]

Abstract

Selectivity is a critical attribute of catalysts used in manufacturing of essential and fine chemicals. An excellent way to induce selectivity in catalysts is by using ultrathin films with tailored nanoporosity. For instance, nanopores can be created in atomic layer deposition (ALD) ultrathin over-coatings on supported metal nanoparticles by subjecting the coatings to high temperature annealing. These nanopores expose the active surface of the underlying metal nanoparticles. The dimensions of these nanopores can be tuned to impart shape selectivity: only reactants or products with a specific size or shape can fit inside the pore. In this work, the authors explore the underlying mechanism driving nanopore formation in ALD films. Ultrathin films of ALD TiO 2 (similar to 2.5 nm thick) and ALD Al 2O 3 (similar to 4.9 nm thick) were deposited on nonporous gamma-Al 2O 3 nanoparticles. The pore formation and evolution were monitored in situ during thermal annealing using small-angle x-ray scattering (SAXS), and the crystallinity was monitored by in situ x-ray diffraction. A correlation between the nanopore formation and amorphous to crystalline phase transitions in the ALD layers was observed. The authors hypothesize that the pores form through the relaxation of stress induced by densification of themore » ALD films during the phase transitions. In conclusion, the authors developed a mathematical model to evaluate this hypothesis and found remarkable agreement between the model and the SAXS measurements.« less

Authors:
 [1];  [2];  [2];  [2];  [3];  [2];  [2];  [2];  [2];  [2]
  1. Univ. of Technology Eindhoven (Eindhoven)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Univ. of Alabama in Huntsville, Huntsville, AL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1471590
Alternate Identifier(s):
OSTI ID: 1421079
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
Additional Journal Information:
Journal Volume: 36; Journal Issue: 1; Journal ID: ISSN 0734-2101
Publisher:
American Vacuum Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Karwal, Saurabh, Li, Tao, Yanguas-Gil, Angel, Canlas, Christian P., Lei, Yu, Mane, Anil U., Libera, Joseph A., Seifert, Soenke, Winans, Randall E., and Elam, Jeffrey W.. Tailoring nanopore formation in atomic layer deposited ultrathin films [Nanopore formation in atomic layer deposited ultrathin films]. United States: N. p., 2017. Web. doi:10.1116/1.5003360.
Karwal, Saurabh, Li, Tao, Yanguas-Gil, Angel, Canlas, Christian P., Lei, Yu, Mane, Anil U., Libera, Joseph A., Seifert, Soenke, Winans, Randall E., & Elam, Jeffrey W.. Tailoring nanopore formation in atomic layer deposited ultrathin films [Nanopore formation in atomic layer deposited ultrathin films]. United States. doi:10.1116/1.5003360.
Karwal, Saurabh, Li, Tao, Yanguas-Gil, Angel, Canlas, Christian P., Lei, Yu, Mane, Anil U., Libera, Joseph A., Seifert, Soenke, Winans, Randall E., and Elam, Jeffrey W.. Wed . "Tailoring nanopore formation in atomic layer deposited ultrathin films [Nanopore formation in atomic layer deposited ultrathin films]". United States. doi:10.1116/1.5003360.
@article{osti_1471590,
title = {Tailoring nanopore formation in atomic layer deposited ultrathin films [Nanopore formation in atomic layer deposited ultrathin films]},
author = {Karwal, Saurabh and Li, Tao and Yanguas-Gil, Angel and Canlas, Christian P. and Lei, Yu and Mane, Anil U. and Libera, Joseph A. and Seifert, Soenke and Winans, Randall E. and Elam, Jeffrey W.},
abstractNote = {Selectivity is a critical attribute of catalysts used in manufacturing of essential and fine chemicals. An excellent way to induce selectivity in catalysts is by using ultrathin films with tailored nanoporosity. For instance, nanopores can be created in atomic layer deposition (ALD) ultrathin over-coatings on supported metal nanoparticles by subjecting the coatings to high temperature annealing. These nanopores expose the active surface of the underlying metal nanoparticles. The dimensions of these nanopores can be tuned to impart shape selectivity: only reactants or products with a specific size or shape can fit inside the pore. In this work, the authors explore the underlying mechanism driving nanopore formation in ALD films. Ultrathin films of ALD TiO2 (similar to 2.5 nm thick) and ALD Al2O3 (similar to 4.9 nm thick) were deposited on nonporous gamma-Al2O3 nanoparticles. The pore formation and evolution were monitored in situ during thermal annealing using small-angle x-ray scattering (SAXS), and the crystallinity was monitored by in situ x-ray diffraction. A correlation between the nanopore formation and amorphous to crystalline phase transitions in the ALD layers was observed. The authors hypothesize that the pores form through the relaxation of stress induced by densification of the ALD films during the phase transitions. In conclusion, the authors developed a mathematical model to evaluate this hypothesis and found remarkable agreement between the model and the SAXS measurements.},
doi = {10.1116/1.5003360},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 1,
volume = 36,
place = {United States},
year = {Wed Nov 15 00:00:00 EST 2017},
month = {Wed Nov 15 00:00:00 EST 2017}
}

Journal Article:
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