skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nanoscale Disorder in CaCu3Ti4O12: A New Route to Enhanced Dielectric Response

Abstract

Significant nanoscale disorder of Cu and Ca atomic substitution is observed in CaCu{sub 3}Ti{sub 4}O{sub 12}, based on our integrated study using quantitative electron diffraction and extended x-ray absorption fine structure. Unambiguous identification of this previously omitted disorder is made possible by the unique sensitivity of these probes to valence-electron distribution and short-range order. Furthermore, first-principles-based theoretical analysis indicates that the Ca-site Cu atoms possess partially filled degenerate e{sub g} states, suggesting significant boost of dielectric response from additional low-energy electronic contributions. Our study points to a new route of enhancing dielectric response in transitional metal oxides by exploiting the strong electronic correlation beyond classical static pictures.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930544
Report Number(s):
BNL-80644-2008-JA
Journal ID: ISSN 0031-9007; PRLTAO; TRN: US200904%%779
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 99
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; ATOMS; CALCIUM COMPOUNDS; COPPER COMPOUNDS; DIELECTRIC MATERIALS; DISTRIBUTION; ELECTRON DIFFRACTION; FINE STRUCTURE; OXIDES; SENSITIVITY; TITANATES; VALENCE; X-RAY SPECTROSCOPY; national synchrotron light source

Citation Formats

Zhu,Y., Zhang, J., Wu, L., Frenkel, A., Hanson, J., Northrup, P., and Ku, W.. Nanoscale Disorder in CaCu3Ti4O12: A New Route to Enhanced Dielectric Response. United States: N. p., 2007. Web. doi:10.1103/PhysRevLett.99.037602.
Zhu,Y., Zhang, J., Wu, L., Frenkel, A., Hanson, J., Northrup, P., & Ku, W.. Nanoscale Disorder in CaCu3Ti4O12: A New Route to Enhanced Dielectric Response. United States. doi:10.1103/PhysRevLett.99.037602.
Zhu,Y., Zhang, J., Wu, L., Frenkel, A., Hanson, J., Northrup, P., and Ku, W.. Mon . "Nanoscale Disorder in CaCu3Ti4O12: A New Route to Enhanced Dielectric Response". United States. doi:10.1103/PhysRevLett.99.037602.
@article{osti_930544,
title = {Nanoscale Disorder in CaCu3Ti4O12: A New Route to Enhanced Dielectric Response},
author = {Zhu,Y. and Zhang, J. and Wu, L. and Frenkel, A. and Hanson, J. and Northrup, P. and Ku, W.},
abstractNote = {Significant nanoscale disorder of Cu and Ca atomic substitution is observed in CaCu{sub 3}Ti{sub 4}O{sub 12}, based on our integrated study using quantitative electron diffraction and extended x-ray absorption fine structure. Unambiguous identification of this previously omitted disorder is made possible by the unique sensitivity of these probes to valence-electron distribution and short-range order. Furthermore, first-principles-based theoretical analysis indicates that the Ca-site Cu atoms possess partially filled degenerate e{sub g} states, suggesting significant boost of dielectric response from additional low-energy electronic contributions. Our study points to a new route of enhancing dielectric response in transitional metal oxides by exploiting the strong electronic correlation beyond classical static pictures.},
doi = {10.1103/PhysRevLett.99.037602},
journal = {Physical Review Letters},
number = ,
volume = 99,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Significant nanoscale disorder of Cu and Ca atomic substitution is observed in CaCu{sub 3}Ti{sub 4}O{sub 12}, based on our integrated study using quantitative electron diffraction and extended x-ray absorption fine structure. Unambiguous identification of this previously omitted disorder is made possible by the unique sensitivity of these probes to valence-electron distribution and short-range order. Furthermore, first-principles-based theoretical analysis indicates that the Ca-site Cu atoms possess partially filled degenerate e{sub g} states, suggesting significant boost of dielectric response from additional low-energy electronic contributions. Our study points to a new route of enhancing dielectric response in transitional metal oxides by exploiting themore » strong electronic correlation beyond classical static pictures.« less
  • We report a combined experimental and theoretical study of CaCu{sub 3}Ti{sub 4}O{sub 12}. Based on our experimental observations of nanoscale regions of Ca-Cu antisite defects in part of the structure, we carried out density-functional theory (DFT) calculations that suggest a possible electronic mechanism to explain the gigantic dielectric response in this material. The defects are evident in atomically resolved transmission electron microscopy measurements, with supporting evidence from a quantitative analysis of the electron diffraction and DFT which suggests that such defects are reasonable on energetic grounds. To establish the extent of the defects, bulk average measurements of the local structuremore » were carried out: extended x-ray absorption fine structure (EXAFS), atomic pair-distribution function analysis of neutron powder-diffraction data, and single-crystal x-ray crystallography. The EXAFS data are consistent with the presence of the nanoclustered defects with an estimate of less than 10% of the sample being disordered while the neutron powder-diffraction experiments place an upper of {approx}5% on the proportion of the sample in the defective state. Because of the difficulty of quantifying nanoscale defects at such low levels, further work will be required to establish that this mechanism is operative in CaCu{sub 3}Ti{sub 4}O{sub 12} but it presents a nontraditional plausible avenue for understanding colossal dielectric behavior.« less
  • We report a novel approach for achieving high dielectric response over a wide temperature range. In this approach, multilayer ceramic heterostructures with constituent compositions having strategically tuned Curie points (TC) were designed and integrated with varying electrical connectivity. Interestingly, these multilayer structures exhibited different dielectric behavior in series and parallel configuration due to variations in electrical boundary conditions resulting in the differences in the strength of the electrostatic coupling. The results are explained using nonlinear thermodynamic model taking into account electrostatic interlayer interaction. We believe that present work will have huge significance in design of high performance ceramic capacitors.
  • No abstract prepared.
  • No abstract prepared.