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Non-Stoichiometry at Dislocation Cores in Perovskites and Related Materials

Published online by Cambridge University Press:  02 July 2020

Gerd Duscher
Affiliation:
North Carolina State University, Materials Science and Engineering Department, Raleigh, NC Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN
M. Kim
Affiliation:
Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN Dept. of Physics, University of Illinois at Chicago, Chicago, IL
N.D. Browning
Affiliation:
Dept. of Physics, University of Illinois at Chicago, Chicago, IL
D. K. Christen
Affiliation:
Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN
C. Cantoni
Affiliation:
Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN
S. T. Pantelides
Affiliation:
Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN Vanderbilt University, Department of Physics & Astronomy, Nashville, TN
S. J. Pennycook
Affiliation:
Oak Ridge National Laboratory, Solid State Division, Oak Ridge, TN Vanderbilt University, Department of Physics & Astronomy, Nashville, TN
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Abstract

Z-contrast images and electron energy loss spectra (EELS) were obtained from low angle grain boundaries in SrTiO3 and YBa2Cu3O7-x (YBCO). Z-contrast images are easy to interpret and especially useful for positioning the beam to acquire EELS data from small sample areas [1], because both these techniques can be performed simultaneously.

In high-temperature superconductors even a single grain boundary can reduce the critical current by up to four orders of magnitude. The band-bending model can quantitatively explain this phenomenon. YBCO is a hole-doped superconductor with about one hole per unit cell for optimum doping at x close to zero. It has a structure closely related to the perovskite structure, and Z-contrast images have shown that the dislocation cores are made up of similar structural units as in SrTiO3.[2,3] Our EELS measurements show clear evidence for band bending effects around isolated dislocation cores in an undoped 8° low angle grain boundary.

Type
Quantitative Transmission Electron Microscopy of Interfaces (Organized by M. Rüehle, Y. Zhu and U. Dahmen)
Copyright
Copyright © Microscopy Society of America 2001

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References

[1]Duscher, G., Browning, N. D. and Pennycook, S. J., Phys. Stat. Sol. a 166 (1998) 327.3.0.CO;2-R>CrossRefGoogle Scholar
[2]Kim, M. et al Phys. Rev. Lett, in pressGoogle Scholar
[3]Browning, N D et al Physica C 294 (1998) 183CrossRefGoogle Scholar
[4]Hammerl, G. et al Nature 407 (2000) 162CrossRefGoogle Scholar
[5]This work was supported by the USDOE under contract DE-AC05-00OR22725 managed by UTBattelle, LLC.Google Scholar