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Title: Defect structure of epitaxial CrxV1-x thin films on MgO(001)

Abstract

Epitaxial thin films of CrxV1-x over the entire composition range were deposited on MgO(001) by molecular beam epitaxy. The films exhibited the expected 45° in-plane rotation with no evidence of phase segregation or spinodal decomposition. Pure Cr, with the largest lattice mismatch to MgO, exhibited full relaxation and cubic lattice parameters. As the lattice mismatch decreased with alloy composition, residual epitaxial strain was observed. For 0.2 ≤ x ≤ 0.4 the films were coherently strained to the substrate with associated tetragonal distortion; near the lattice-matched composition of x = 0.33, the films exhibited strain-free pseudomorphic matching to MgO. Unusually, films on the Cr-rich side of the lattice-matched composition exhibited more in-plane compression than expected from the bulk lattice parameters; this result was confirmed with both x-ray diffraction and Rutherford backscattering spectrometry channeling measurements. Although thermal expansion mismatch in the heterostructure may play a role, the dominant mechanism for this phenomenon is still unknown. High resolution transmission electron microscopy was utilized to characterize the misfit dislocation network present at the film/MgO interface. Dislocations were found to be present with a non-uniform distribution, which is attributed to the Volmer-Weber growth mode of the films. The CrxV1-x / MgO(001) system can serve asmore » a model system to study both the fundamentals of defect formation in bcc films and the interplay between nanoscale defects such as dislocations and radiation damage.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1130645
Report Number(s):
PNNL-SA-93687
Journal ID: ISSN 0040-6090; 46001; KC0201020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Thin Solid Films
Additional Journal Information:
Journal Volume: 550; Journal Issue: C; Journal ID: ISSN 0040-6090
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Environmental Molecular Sciences Laboratory

Citation Formats

Kaspar, Tiffany C., Bowden, Mark E., Wang, Chongmin, Shutthanandan, V., Manandhar, Sandeep, van Ginhoven, Renee M., Wirth, Brian D., and Kurtz, Richard J. Defect structure of epitaxial CrxV1-x thin films on MgO(001). United States: N. p., 2014. Web. doi:10.1016/j.tsf.2013.09.067.
Kaspar, Tiffany C., Bowden, Mark E., Wang, Chongmin, Shutthanandan, V., Manandhar, Sandeep, van Ginhoven, Renee M., Wirth, Brian D., & Kurtz, Richard J. Defect structure of epitaxial CrxV1-x thin films on MgO(001). United States. https://doi.org/10.1016/j.tsf.2013.09.067
Kaspar, Tiffany C., Bowden, Mark E., Wang, Chongmin, Shutthanandan, V., Manandhar, Sandeep, van Ginhoven, Renee M., Wirth, Brian D., and Kurtz, Richard J. 2014. "Defect structure of epitaxial CrxV1-x thin films on MgO(001)". United States. https://doi.org/10.1016/j.tsf.2013.09.067.
@article{osti_1130645,
title = {Defect structure of epitaxial CrxV1-x thin films on MgO(001)},
author = {Kaspar, Tiffany C. and Bowden, Mark E. and Wang, Chongmin and Shutthanandan, V. and Manandhar, Sandeep and van Ginhoven, Renee M. and Wirth, Brian D. and Kurtz, Richard J.},
abstractNote = {Epitaxial thin films of CrxV1-x over the entire composition range were deposited on MgO(001) by molecular beam epitaxy. The films exhibited the expected 45° in-plane rotation with no evidence of phase segregation or spinodal decomposition. Pure Cr, with the largest lattice mismatch to MgO, exhibited full relaxation and cubic lattice parameters. As the lattice mismatch decreased with alloy composition, residual epitaxial strain was observed. For 0.2 ≤ x ≤ 0.4 the films were coherently strained to the substrate with associated tetragonal distortion; near the lattice-matched composition of x = 0.33, the films exhibited strain-free pseudomorphic matching to MgO. Unusually, films on the Cr-rich side of the lattice-matched composition exhibited more in-plane compression than expected from the bulk lattice parameters; this result was confirmed with both x-ray diffraction and Rutherford backscattering spectrometry channeling measurements. Although thermal expansion mismatch in the heterostructure may play a role, the dominant mechanism for this phenomenon is still unknown. High resolution transmission electron microscopy was utilized to characterize the misfit dislocation network present at the film/MgO interface. Dislocations were found to be present with a non-uniform distribution, which is attributed to the Volmer-Weber growth mode of the films. The CrxV1-x / MgO(001) system can serve as a model system to study both the fundamentals of defect formation in bcc films and the interplay between nanoscale defects such as dislocations and radiation damage.},
doi = {10.1016/j.tsf.2013.09.067},
url = {https://www.osti.gov/biblio/1130645}, journal = {Thin Solid Films},
issn = {0040-6090},
number = C,
volume = 550,
place = {United States},
year = {2014},
month = {1}
}